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1. rrr rrr rettet s 9 2 d R CPUESETINPUT MODE nter 10 2 12 troie teo E tese E didt LL AM ae ates 11 2 1221 Sien Magnitude aa cc AAAS et oad pans e ee ere IR ers 11 2 12 2 Locked AntisPh se iiit tee e bee rear a pre Pene S FERE CE EE 11 3 BRAKING BEHAVIOR vescosesvess secs sea eoe eaae 11 4 THEORY OF OPERA TION dusudsesssaucees enccssssenesssuvesedsese 12 4 1 TRAJECTORY CONTROL tiere i nta eiui iE Eu 13 4 2 UNITSOF MEASUREMENT on 15 4 2 1 Velocity Equation Serde eet Ree ere dee adden e Get dde ee 16 4 2 2 Acceleration Equations eseist ei aii ri entente entente intent enne 16 4 2 3 Example Torque Calculation eese eese entren eene ene 16 5 INTERNAL REGISTERS oo ede e USE ep Fo EN CSS Up sai ens 18 5 1 COMMAND BEGISTERS 5 d ohereieide teer epit ied edet iet 18 5 2 REGISTER MEMORY MAP 19 5 3 ANALOG REGISTERS S 22 5 4 MOTION TRAJECTORY 5 6 0 00000 00 0 200 0
2. ORD 161 3 inches sec 256 0 00051 10 4750 9 42 A 542 So now we know the maximum setting possible for use in our trajectories Setting value higher than this will exceed the capacity of our motors and will result in high errors and overshoot Keep in mind that when using trajectories the velocity you choose should be an even multiple of the acceleration In this example valid velocities include 5420 8130 11382 etc Any even multiple of 542 that is within the bounds of valid velocities 32768 to 32767 2005 Gamatronix Page 17 of 45 Gamoto Gamoto 5 Internal Registers The host controls the Gamoto by writing to and reading from various internal registers Each section below describes the name address and purpose of each internal register Where applicable an R W or R W is shown indicating whether the register is Read only Write only or Read Write respectively Note that registers in locations 34 44 can be changed and stored to flash to allow different power on conditions 5 1 Command Registers Almost everything you need to do to control the Gamoto can be done by reading or writing to the internal registers However there are a few special cases of standalone commands listed below that require different treatment Writing to any of these registers will execute the command The data that is written is not important in fact you don t need to write any data at all A
3. 22 5 5 MODE REGISTER 24 5 6 MODE2 REGISTER 25 6 COMMUNICATION PROTOCOLS ssscccsssssscssssscccssssecssssscccsssscccessceccscssccsesssececcsssecsecssseceeses 25 6 1 DIPS WITCH SETTINGS bes suaevs a O use EE 26 6 2 COMMUNICATION PROTOCOLS 5 0 0 00 26 6 2 1 Example Write 1234 to Kp Register 27 6 2 2 Example Write Response nei ere dO a Rl qe RE TRE e ER YR PIRATES 27 6 2 5 Example Read from Kp Register tto tn ee ree 27 6 2 4 Example Read Response octo te re RE t re E EFE REIP 27 6 3 COMMUNICATION PROTOCOLS PC tette tette ttt teet tete 27 6 3 1 Example 2 byte Write to Kp register 28 6 3 2 Example 2 byte Read from Kp 29 2005 Gamatronix Page 2 of 45 Gamoto Gamoto 6 4 COMMUNICATION PROTOCOLS CRICKET BUS ccccccceeseeesesesesesesesesesesesesesevesesesesesesesesesereseserens 29 6 4 1 The Cricket Command Word eese eene hheheh esee 30 6 4 2 RW Z Address Byte ete a ete REPE GRE FERRE E Fee EU ERR EE 30 6 4 5 MEE IEEE 30 6 4 4 JB 71r REPRE 30 6 4 5 Cricket Logo Example Reading and Writing Registers esee 31 7 MECHANICAL SPECIFICATIONS 32 8 ELECTRICAL CONSIDERATIONS eva do po ea Pw uaa Cora a uber
4. call I2CWrite Galil LACSiceo Low byte of data to write High byte of data to write Se Sie cone 1 See Appendix for the C library routines Additional bytes can be added before the stop condition They will be written in the next sequential memory location There is no limit on the quantity of bytes that can be written at one time 6 3 2 Example 2 byte Read from Kp register A two byte register read is as follows I2C Example Written PIC Assembly cell ES Ea nE movlw SLAV EID movlw 0x22 cell 32OWheiie call I2CRepStart movlw SLAV 1 call I2CWrite call I2CReadwAck MOME I2CData w movwf RegDataLSB call I2CRead movft I2CData w movwf RegDataMSB call I2Cstop 2 byte read from Kp register I2C subroutines not shown Send control byte W Set pointer to Kp register Send control byte R First read is with ACK Store LSB result Read without ACK signals last read Store MSB result See Appendix B for the library routines Note that the master should not ACK the last read This signals the end of the read operation To perform a one byte read the one and only read should not be with an ACK since it is the last read 6 4 Communication Protocols Cricket Bus Before using the Cricket Bus make sure the bus is enabled by checking the dip switch settings If you will be using more than one Gamoto
5. Gamatronix Gamoto 1 User s Manual Gamatronix Motor Controller Integrated PID Servo Motor Controller Driver User s Manual Rev U Documents the following versions Firmware through rev 21 MotoView Software v 1 0 14 and later PCB Hardware rev E F Gamoto TABLE OF CONTENTS WARRANTY c M 4 DISCLAIMERS 4 Ep 4 EQUIS X c 5 1 1 TECHNICAL SPECIFICATIONS err Per E t terit irte ver 6 1 1 TYPICAL APPLICATION 6 E bet r tbe storage aeter babet oria E a eee eb vereris 7 2 OPERATIONAL 2 ss ott poo Pe ea o Pre E SHE PERRO o eR Irae e Pea Ka egg 7 2 1 Io HNIC EE 7 2 2 POWER MODE visi cT 7 2 3 VELOCITY MODE 5 5 aiii diete dte AEE RES T 2 4 TRAJECTORY ie coe intere ye ue us ev Sexe es tau even eu vd eve w ed 8 2 4 1 Trajectory Stop aues qtto bae site adt RISE Ree 8 2 5 HOMING MODE 7 8 2 6 MOTIONDONE ENABLE 8 2 7 SERIAESHARE ENABLE tri cute ounces ix ERU 9 2 8 115200 BAUD RATE 9 2 9 STEP DIRECTION PULSE INPUTS onica esinte raea aa nre rere rere nnn 9 2 10 ANALOG FEEDBACK MODE sinian iraa iate
6. Step signal input UL 3 Upper Limit switch input Direction signal input R C pulse input Reset 4 Reset line for Gamoto processor Momentarily pull this line low to reset Gamoto This connector is used to add limit switch interlocks to your control system By pulling the Lower Limit input low clockwise motion of the motor will be disabled until the line is released there is an internal pull up resistor in the Gamoto If the Upper Limit input is pulled low counter clockwise motion will be disabled until the line is released This allows a mechanism of preventing travel beyond a mechanical limit by adding limit switches at each end of the travel When in Step Direction mode pins 2 and 3 are used for Step Direction respectively When in R C Pulse mode pin 3 is used for the R C pulse input which allows connection of the standard R C cable pin out Gnd 5V signal on pins 1 2 3 Connecting 5V to pin 2 is not needed but has no ill effect and is convenient for this mode of operation see warning below NOTE When connecting an R C signal cable to J4 remember that all pins have a 5V maximum If your servo cable carries more than 5V on the middle pin pin 2 LL it will damage the Gamoto so you must not connect this pin In this case it would be better to remove the pin or wire for this signal and connect only GND and the 5V R C pulse signal There is also a reset pin available to allow an external processor to electrica
7. a dummy data byte must be sent in order to read each byte So to read a three byte register you must send the CricketCMD byte RW Address byte RegNum then a dummy data byte Read the first byte Send a second dummy byte then read the next byte Send a third dummy byte then read the final byte 6 4 5 Cricket Logo Example Reading and Writing Registers Using the Handy Cricket to control the Gamoto is very easy Below is an example of using Cricket Logo to read and write to 8 bit Gamoto registers The command to send a byte out the Cricket bus is bsend and to read a byte is bsr Every bsr command must be followed by a dummy data byte which is used to trigger the read operation The Gamoto has been assigned the Cricket Class ID of 17 11 hex All Gamotos respond to the class ID The first byte to send is the command bit 100 11 111 Then they look at the next byte the or address to see if the command is for them This number must match the address set by the dipswitches on the Gamoto Write to an 8 bit Gamoto register to gxSetReg8 reg val adr bsend 111 bsend adr bsend reg bsend low byte val end Read from an 8 bit Gamoto register to gxReadReg8 reg adr bsend 111 bsend adr 128 bsend reg output bsr 1 end A full set of Cricket library routines for controlling the Gamoto is available at the Gamatronix web site By pasting these routines into your Cricket program you can be control
8. the setPosition is 0 and actual position mPosition is 0 so the motor will not move However if it is disturbed or pushed one way it will drive to return to the target position The PID algorithm see Theory of Operation section determines the power sent to the motor In the windows control software there is an interactive mode that demonstrates position control based on mouse movements 2 2 Power Mode Mode Register 00010001 0x11 Enabled by setting PwrMode bit of Mode register This mode is the simplest to use and to understand In this mode a raw motor power number is sent to the Gamoto as a percentage of power desired to send to the motor This register mPower is a signed 8 bit number and can range from 128 to 127 0 0 power 127 100 forward 128 10096 backwards In this mode the encoders are ignored so in fact encoders are not necessary However if encoders are connected then the current position and velocity can be read from the internal registers while the motor is running 2 3 Velocity Mode Mode Register 0000101 0x05 Enabled by setting the VelMode bit of the Mode register This mode allows easy control of 2005 Gamatronix Page 7 of 45 Gamoto Gamoto motor velocity while still tracking the absolute position When this mode is set the value in register SetVelocity is used as a velocity target Setting SetVelocity 0 causes the motor to stop SetVelocity is a signed 16 bit register and t
9. 00051 10 20 150 18 3003 65 A inches sec 3003 65 9 42 4750 5 96 inches sec A relative to g 5 96 12 32 2 0 015 9 4 2 3 Example Torque Calculation Let s assume we are powering our robot with two motors capable of 20 oz in of torque What value should we use for the Gamoto acceleration setting Assume our robot weighs 4 lbs 6402 2005 Gamatronix Page 16 of 45 Gamoto Gamoto First since we have two wheels we have 2 x 20 40 oz in of torque available Now the definition of torque is force times distance Torque 40 2 Force x Wheel Radius so solving for Force F T r Force 40 oz in 1 5 inches 26 7 oz 1 67 Ibf So now we know the Force we want How does this relate to acceleration F Newton s Law so a First we need to know the mass in Ibm which is equal to its weight divided by g m 4 Ibf 4 32 2 0 124 Ibm 1 67 Ibf 0 124 Ibm 13 44 ft sec 13 44 ft sec X 12 in ft 161 3 in sec Now we know the acceleration in that we are shooting for To summarize all of the above calculations we can use this condensed expression 24 15 A in sec W r Where T Total Torque in oz in W Weight in pounds and r wheel radius in inches Now we need to use the acceleration equations backwards to deduce what we should use for our A setting A inches sec 256 To dS
10. 127 will cause full forward power setting mPower 128 128 will cause full reverse power A setting of 64 192 will cause 50 reverse power 90 5A RCPraw Raw R C pulse counts 5000 counts 1ms This holds the length of the last R C pulse received Only used while in R C mode 97 61 u0 Error term Signed 24 bit number This is the difference between the target position setPosition and actual motor position mPosition Read this value to detect if an obstacle or friction is causing a large difference between the goal and actual position or velocity 178 B2 version Firmware version number Integer from 1 to 255 Read only 179 B3 StepSize Number of steps to jog when step dir input is enabled and Gamoto receives a step pulse 226 E2 SPmin setPosition Minimum This is the minimum value that will be set by an incoming R C pulse Refer to the R C mode description 228 E4 SPmax setPosition Maximum This is the maximum value that will be set by an incoming R C pulse Refer to the R C mode description 230 E6 RCPmin R C Pulse minimum This is the minimum pulse length accepted by the Gamoto Shorter lengths will be clipped to this length The units are in raw counts 5000 counts 1 ms 2005 Gamatronix Page 20 of 45 Gamoto Gamoto 232 E8 RCPmax R C Pulse maximum This is the maximum
11. 3 Jumpers 9 3 1 JP1 Motor Power Jumper This jumper bridges the Motor Power supply with the Logic Power supply See section 8 Electrical Considerations for details and precautions about using this jumper 9 3 2 JP2 Cricket Power jumper This jumper bridges the logic power for the Gamoto to the power on the Handy Cricket if you have a Cricket connected to the cricket cable This allows you to use either only the Handy Cricket s power supply or only the Gamoto power supply Care should be take not to use the jumper when both supplies are present 9 3 3 JP3 Encoder 1X 4X Setting Rev F and later boards only This jumper selects between 1X and 4X encoding for the quadrature encoders A setting of 4X allows a 500 count encoder to have 2000 pulses per revolution by triggering on the pulse edges rather than each complete pulse cycle This feature is only available on rev F and later boards 9 4 J1 Analog Inputs J1 Row Analog Inputs G 1 Ground V 2 5 VDC output Can be used to supply power to external sensor A 3 Analog voltage input 0 5VDC This connector is used to connect up to four analog inputs For each of the four channels A1 A4 a separate power and ground pin is available making it easy to keep cabling simple and to provide power to an analog sensor such as the Sharp GP2D12 sensor NOTE Analog Channel 4 pin A4 can be used to connect a Home Switch if the Homing mode is enabled see
12. have no effect 2 5 Homing Mode Mode2 Register 00000001 0x01 This mode is normally disabled Enabled by setting bit 0 of the Mode2 register this mode allows an external home switch to clear the position register and stop the motor automatically It changes two of the analog pins to digital pins Analog pins 2 and 4 and uses Analog channel 4 Connector J1 pin A4 as a home switch input Normally high you need to supply a pull up resistor of 1K 50K when pulled low while in Velocity mode the position registers are cleared Velocity is set to 0 and the mode will change to Position mode stopping the motor The second converted digital channel A2 is not used for this homing feature and will still read analog values even though it is configured as a digital pin 2 6 MotionDone Enable Mode2 Register 00000010 0x02 This option is normally disabled Enabled by setting bit 1 of the Mode2 register this option turns one of the analog pins A2 into an output and uses it to signal when a motion profile has been completed A2 goes high This can be used as an interrupt to an external MCU or other control system in place of polling the Mode register to detect when a motion is 2005 Gamatronix Page 8 of 45 Gamoto Gamoto complete As with the Homing mode pin A4 becomes a digital pin but is still able to read analog input voltages 2 7 SerialShare Enable Mode2 Register 00000100 0x04 This option is normally disab
13. mode If the Direction signal is high then each rising edge of the Step signal will jog the motor one count forward setPosition gets incremented If the direction signal is low the setPosition register gets decremented StepSize Register Address 0xB3 or 179 decimal If you want each step pulse to jog more than one count use the StepSize register to set the step size to something larger than 1 For example if StepSize 10 then each incoming step pulse will jog the motor to mPosition 10 2 10 Analog Feedback Mode Mode2 Register 00100000 0x20 This mode allows Analog Channel 1 to be used as the position feedback rather than quadrature encoder signals This makes it easier to convert a simple motor to a servo without the need for a costly quadrature encoder The 0 1023 signal is fed directly to the mPosition register and the encoder inputs are ignored 2005 Gamatronix Page 9 of 45 Gamoto Gamoto 2 11 R C Pulse Input Mode Mode2 Register 01000000 0x40 This mode allows the Gamoto to accept standard R C Remote Control input pulses to command the motor set point These R C pulses are generally in the range of 1ms 2ms wide pulses repeated every 20ms The Gamoto accepts any pulse in the range of 0 2ms to 3ms and the repeat rate is not important To configure the low and high pulse range and low and high desired set points use the MotoView R C Pulse configuration dialog under the Tools menu This dialo
14. one signal The zero power condition is represented by a 50 duty cycle Full forward is 100 duty cycle and full backward is 0 duty cycle The reason for this behavior is that this pin is connected to the Direction input of the H bridge so that at 50 power the motor is actually reversing direction constantly which averages out to zero net power The other pin on the H bridge that is normally used for PWM input is now used to enable or disable the motor The advantages and disadvantages of these PWM modes have been much debated in the motor control community If you don t have an opinion use the default Sign Magnitude mode If you have a very free spinning motor and would like more of a braking effect when slow or stopped then you should try LAP mode 3 Braking behavior The LMD18200 Dual H Bridge chip has a braking feature that in the case of the Gamoto is controlled by one bit the Brake bit in the Mode byte When the Brake bit is set the Brake pin on the bridge goes high When the Brake bit is clear the Brake pin goes low The first confusing point is that this type of braking usually does not stop a motor and is sometimes a barely noticeable effect It works by effectively shorting the motor coil leads 2005 Gamatronix Page 11 of 45 Gamoto Gamoto together With some motors this causes a strong resistance to spinning and other motors just seem sluggish It s best to think of it as a way to red
15. precise control of position velocity and 49 acceleration 3 fos e Step Direction pulse inputs to work with 0 stepper motor driver software tO riz 4059 o 5 e R C Pulse input to work with Remote EC eT 55 aaa 559 2 a Control radios hobby servo systems Q 58888 p 5 E ce O AL AZASA4 5 GANATRONIX 127 GANOTO 1 REV F 1X and 4X quadrature encoder decoding C slave interface for motor control by an external 2 Serial interface 9600 19200 115200 baud Cricket Bus interface for use with Handy Cricket control bus products Removable motor power fuse with fuse fail indicator On board flash memory to store parameters Analog reading of real time motor current Limit switch interface to add optional upper limit lower limit and home switch inputs Expansion port with four analog input pins available for general purpose analog readings 1 Overview The Gamatronix Gamoto is an integrated module that includes a PID Proportional Integral and Derivative control chip a motor driver and quadrature encoder interface conditioning circuitry step direction pulse input circuit and an R C Pulse capture circuit A complete motor control system would include the Gamoto a motor power supply and a quadrature encoder or analog potentiometer for position feedback The Gamoto can also be used in direct power mode open loop in which case the position feedback is not necessary The host processo
16. pulse length accepted by the Gamoto Longer lengths will be clipped to this length The units are in raw counts 5000 counts 1 ms 2005 Gamatronix Page 21 of 45 Gamoto Gamoto 5 3 Analog Registers These registers are all two byte 16 bit memory locations but there is only 10 bits of resolution The data is right justified to the LSB that is the LSB is the first byte and it contains the lower 8 bits and the next byte contains the upper two bits of the analog value The upper remaining bits are padded with zeros Example of register mapping for Analog0 register MSB LSB zero padding 110111110111 0111011 161 1 160 A0 This table shows the addresses for all of the analog registers Note that AnalogO is a special case it is tied to the motor current output signal from the H Bridge DEC Register Len Description 160 AnalogO 2 This is wired directly to the H Bridge and provides a reading proportional to Motor current Reading translates to approximately 186 counts amp with max reading of 1023 counts 5 5 Amps 162 A2 1 2 input 1 Scale is 0 5V with 10 bit resolution making the register minimum 0 maximum 1023 164 A4 Analog2 2 Analog input 2 Scale is 0 5V with 10 bit resolution making the register minimum 0 maximum 1023 166 A6 Analog3 2 Analog inp
17. the event that the distance specified is short and acceleration is small then the velocity may never be achieved This is not a problem for the Gamoto but it is good to be aware of this possibility A diagram showing this situation is shown here Target Velocity v Detecting the end of the trajectory This diagram shows a trajectory move and how the Mode byte changes and the MotionDone pin signals the end of the trajectory if MotionDone is enabled in the Mode2 byte Motor Speed Pin A2 J1 MotionDone pin Mode Byte Mode 1 Mode 3 Mode 1 NOTE It s important to note that by Trajectory Done it means that the position setpoint setPosition has reached its target value not that the actual position has reached the 2005 Gamatronix Page 14 of 45 Gamoto Gamoto target value There are several reasons for this The main reason is that there is no good way to tell if the position has been reached i e what if it reaches it briefly but then overshoots the position What if it comes close but due to the P I D settings there is some steady state error How long should it settle at the destination before declaring it has arrived If it never reaches what should the timeout behavior be All of these questions will have very different answers depending on the application so we have left it to the user to decide The idea is the user would implement this kind of use case e D
18. 3 to run the trajectory To determine when it s complete you can poll the Trajectory Mode bit in the Mode byte Or you can turn on MotionDone Enable by setting Mode2 bit 1 and monitor pin A2 on J1 This pin is normally low and will go high when the motion is complete e The distance value is always a relative distance to be added to the current position When using trajectories it s a good idea to follow these guidelines e For negative moves use a negative x or negative v but never use a negative acceleration e v a should be an integer especially for large values of v and or a For example if v 5000 and a 1000 then after 5 cycles v will become 5000 and will stop increasing But if a21100 then after 4 cycles it will be 4400 and after 5 cycles will overshoot to 2005 Gamatronix Page 13 of 45 Gamoto Gamoto 5500 and then stop increasing In the extreme case of v close to the maximum value 32767 and large values of a then the velocity can roll over to a negative value e f the maximum v is not fast enough decrease dS e lf the minimum v is not slow enough increase dS e Reminder Changing dS will also affect the strength of the Kd term in a linear fashion Maximum values for trajectory variables Var Length Range X 3 bytes signed integer 8388608 to 8388607 V 2 bytes signed integer 32768 to 32767 a 2 bytes signed integer 0 to 32767 Special case Short Trajectory In
19. 5 Gamoto Gamoto 13 Appendix C FAQs Frequently Asked Questions 1 What if my motor doesn t have encoders or don t want to use encoders No problem Set the mode to Power mode and use the mPower register to manually control power to the motor 2 want to use a 6 volt motor but the spec sheet says minimum 12 volts Am I out of luck No Just set the max power to 5096 and there will never be more than 6V of power to your motor even though you are running off a 12 Volt battery Similar power limiting can be done for any combination of battery levels and motor limitations 3 My Gamoto was working fine but now the motors won t run What s wrong Most likely your battery has run down to less than 12 Volts Double check the voltage and make sure it reads at least 12V under load 4 My Gamoto board is dead The green power light does not light when power is connected What s wrong Most likely the 5V regulator has been damaged either by reversed polarity or a short of some kind Replace the 5V regulator 5 Is the Gamoto firmware field upgradeable Yes itis Please contact us at sales gamatronix com for details to upgrade your Gamoto firmware 6 Ared LED is lit on the board My Gamoto is communicating but the motors are dead l ve checked the voltage levels and they re fine What s wrong Your fuse has blown or is missing Remove and check it for continuity See the section in the User s Manual on fuses to fin
20. Homing Mode description 2005 Gamatronix Page 34 of 45 Gamoto Gamoto NOTE Analog Channel 2 pin A2 can be used as an interrupt output or MotionDone if this is enabled by configuring Mode2 In this case it becomes a normally high output pin and goes low during a trajectory and high when a trajectory is finished NOTE Analog Channel 1 connector can be used for the Analog Feedback feature This allows the use of a potentiometer or analog voltage in place of a quadrature encoder NOTE Analog Channel 0 is not available on this connector because it is dedicated to reading motor current It is connected to the H bridge on the Gamoto board 9 5 J2 Motor Power Input and Output J2 Pin Motor Power Input This supplies power for the Motor M 1 Output to Motor winding Reverse these to change motor direction Output to Motor winding Reverse these to change motor direction 2 V 3 12 55 VDC input Current consumption up to continuous 6A peak 4 Ground Maximum motor input voltage will be limited to 16 volts if jumper JP1 is used tying together the logic and motor voltage inputs This connector is used both to supply motor power and to distribute power to the motor G and V should be connected to a battery or other high current voltage source Pins M and M should be connected to the motor windings The polarity of these terminals is usually determined by trial and error If the mot
21. ISOLL LOH 0801090 0 2950 24250 IMOOL Pv CNWICWY ONV OVd AHL HTOW ad Ov IN 2 l ev Yas AWZ b A Ul dM 21607 LNISOTWNY ZNISOWNY E NI SOTWNY OOTVNY uj amipeno Bd LNI2Od OND a 2 12 S8d SINIOd 1SH Gamoto Page 40 of 45 2005 Gamatronix Gamoto 11 Appendix A Factory Default values Below are the factory defaults of the flash registers These values can be restored at any time by writing to the command register FactoryRst Register Factory Default Value Kp 500 Ki 3 Kd 200 iLimit 5000 ds 10 Mode 1 pwrLimit 255 Mode2 0 To change the value that these registers will have at power up simply set them to the desired values and then write to the command register SaveParms to save them to flash memory Now every time you power up the values you programmed will be set To revert back to the original factory values at any time write to the FactoryRst command register 2005 Gamatronix Page 41 of 45 Gamoto Gamoto 12 Appendix B lC Subroutines for PIC Assembly The following routines can be used with a PIC microcontroller to implement I C Master The sample code is for a 20MHz clock but can easily be adapted to other clock spe
22. ails Please refer to the Handy Cricket website for more details on the cricket bus 6 4 2 RW Address Byte R W 0 0 0 0 A2 1 0 Read 1 Broad Dipswitch Dipswitch Dipswitch Write 0 cast 3 4 5 The high bit of the RW Address byte is set to 0 for Writing 1 for Reading The lower 3 bits are set to the unit address of that particular Gamoto controller and must match the dipswitch settings for the unit address Broadcast Address To send a command simultaneously to all Gamotos on the bus set the broadcast bit This is the same as using a device address of 8 rather than the usual 0 to 7 This is convenient for starting two motors at the same time i e two wheels on a robot Note that the broadcast address only works for WRITE operations Read operations would cause conflicting responses 6 4 3 RegNum The register number corresponds to the starting address of the register you wish to write read to from Please note that many registers have fractional components so you need to pay close attention to the register map to make sure you are accessing the correct starting point of the register 6 4 4 Data The data following a write command can be a maximum of four bytes After each byte is written the internal pointer is incremented allowing sequential writes to a range of register 2005 Gamatronix Page 30 of 45 Gamoto Gamoto bytes When reading using the cricket bus
23. amatronix Page 12 of 45 Gamoto Gamoto So the resulting equation is mPower Kix fudt Kd x mVelocity One more final scaling is performed to allow the use of motors that cannot handle the full voltage of the power supply For example if you are using a six volt motor with a 12 Volt battery you can set pwrLimit 50 power or 127 The final equation then is mPower Ko xu Kix Kd x mVelocity x pwrLimit 255 4 1 Trajectory Control As mentioned in the velocity mode section velocity is controlled by continuously adding to the position set point In the same manner adding to the velocity set point can cause a constant acceleration These techniques are combined along with distance planning and deceleration to create a Trajectory Move The diagram below shows a normal trajectory move A Velocity Acceleration a a Distance x gt X Given a desired distance velocity and acceleration a move can be completed smoothly and accurately You can create and test these trajectories easily using MotoView Once you decide a few trajectories that you will use in your application you can store up to seven of them in flash Or you can create them and run them on the fly To run a trajectory the following steps are necessary e Write to the desired X V and A trajectory registers e Write the corresponding trajectory number to the TrajNum register Set Mode to 0x0
24. at your potentiometer and see what values you get for feedback If your analog1 channel is showing values from 8 to 1019 then you could set SPmin to 10 and SPmax to 1015 You wouldn t want to set the min max values outside of your actual range or else you could reach the mechanical limit of your motor motion and the motor would still be trying to drive 2 12 PWM Modes There are two available modes for controlling the power to the motor Both use Pulse Width Modulation PWM which is a digital way of delivering a range of power to a device Depending upon the motor design and application it may be desirable to use one mode over another 2 12 1 Sign Magnitude Sign Magnitude is the default mode This method requires that two signals be sent to the H bridge direction Sign and Magnitude The Magnitude is always positive and the direction changes depending on which way the motor is to be driven The Magnitude signal is a square wave with a fixed base frequency of 19 2 kHz and varying duty cycle from 0 to 100 corresponding to 0 and 100 power delivered to the motor The Sign or direction signal is a digital high for clockwise rotation and low for counter clockwise motion 2 12 2 Locked Anti Phase To enable Locked Anti Phase LAP mode set the LAP PWM bit in the Mode byte Any time you change this bit you need to save to Flash then power cycle before it takes effect In LAP mode direction and magnitude are combined into
25. d ordering information 7 Where ask more questions and share experiences with other users Join the Gamatronix Yahoo forum The web page is at http groups yahoo com group gamatronix 2005 Gamatronix Page 45 of 45 Gamoto
26. dle 1 I2C WFI movf SSPCON2 0x80 W Check all busy bits andlw 0 1 Skipz goto I2C WFI ifset SSPSTAT Ox80 R goto 5 1 return I2CStart call I2CWaitForIdle banki bsf SSPCON2 0x80 S return Initiate Start 2 I2CRepStart call I2CWaitForIdle 1 bsf SSPCON2 0x80 RSEN Initiate Repeated Start return I2CStop call I2CWaitForIdle 1 bsf SSPCON2 0x80 PEN Initiate stop return I2CRead call I2CWaitForIdle banki bsf SSPCON2 0x80 RCEN Initiate receive call I2CWaitForIdle movf SSPBUF W movwf I2CData call I2CWaitForIdle banki bsf SSPCON2 0x80 ACKDT Don t send an ACK EEPROM doesn t require it bsf SSPCON2 0x80 ACK return z Initiate ACK sequenc I2CReadwAck Same as I2CRead but we send an ACK this time call I2CWaitForIdle banki bsf SSPCON2 0x80 RCEN Initiate receive call I2CWaitForIdle movf SSPBUF W movwf I2CData call I2CWaitForIdle bank1 bcf SSPCON2 0x80 ACKDT Send an ACK this time bsf SSPCON2 0x80 ACKEN Initiate ACK sequenc 2005 Gamatronix Page 43 of 45 Gamoto Gamoto return I2CWrite movwf I2CData Save input value call I2CWaitForIdle movf I2CData W movwf SSPBUF call I2CWaitForIdle Can capture ACK return value here in SSPCON2 ACKSTAT if desired return 2005 Gamatronix Page 44 of 4
27. drature Encoder input signal Phase A B 4 Quadrature Encoder input signal Phase B This connector is used to power the encoders and to receive the encoder input signals The two inputs A and B should be out of phase with each other to indicate motor direction as shown below Encoder A Encoder B d ge Please note that if a normal LED is connected directly to this power supply a current limiting resistor must be used to avoid damaging the LED Most commercial encoder modules have these resistors included and some LEDs have current limiting built in Check the encoder or LED datasheet to be sure 9 10 J7 Interface J7 Pins lC Communication Interface SDA 1 2 Data signal This is open collector 5V logic signal with pull up resistor 2005 Gamatronix Page 37 of 45 Gamoto Gamoto CLK 34 Clock signal This is an open collector 5V logic signal with pull up resistor G 5 6 Ground This connector is used to control the Gamoto from an I C Master device such as microcontroller MCU The clock CLK and data SDA lines are held high by pull up resistors on the board and are pulled low when active Note that the two connectors are wired in parallel for easy daisy chaining of 1 devices 2005 Gamatronix Page 38 of 45 Gamoto Gamoto 9 11 J8 Logic Power Input 48 Pin Logic Power Input This supplies
28. e ee 32 9 CONNECTOR PINOUTS sssssssssssessesestsbscessscssevenscssescsseetesceichesssscusedeossvecssbescesssbubicessinesdssseessessscensesss 33 9 1 TEED INDICATORS Ui T 33 9 2 e ni 34 9 3 TIP ANALOG INPUTS ke ge WO ele 34 9 4 J2 MOTOR POWER INPUT AND 35 9 5 J3 CRICKET BUS CONNECTOR 5 ee peer e 35 9 6 LIMIT SWITCH INPUTS AND 5 36 9 7 JS SERTAL INTERFACE knee eee ERE ee be eee e eie reis 37 9 8 J6 BENCODER INPUTS ete eter tee bete eet eee i RRS 37 UO JESDCINTERBAGE SA O ah Su M LE Ma MA DEM EE 37 910 JS LOGICPOWER INPUT eheu cecidere RI 39 10 SCHEMATIC DIAGRAM ae db auge ep eR en aeuo ra ovde ve 40 11 APPENDIX A FACTORY DEFAULT VALUES e eee ee ette e 41 12 APPENDIX B SUBROUTINES FOR PIC ASSEMBLY 42 13 APPENDIX C EAQS teseseseeces teat vs ecce ees deae 45 2005 Gamatronix Page 3 of 45 Gamoto Gamoto Warranty The software libraries and tools are provided as is without warranty The ent
29. e number of bytes we want to read In this case we are requesting two bytes back and the result is 1234 hex 6 2 4 Example Read Response 6 3 Communication Protocols ACK Data LSB Data MSB CHECKSUM 41 34 12 87 lt Checksum gt To communicate with the Gamoto using I C the first step is to enable I C Turning ON 2005 Gamatronix Page 27 of 45 Gamoto Gamoto dipswitch 1 enables this mode It should be in the ON position for I C communication The next step is to set the address bits dipswitches 3 4 and 5 If you only have one Gamoto controller you can leave it at the factory setting of 000 switches 3 4 5 all OFF However if you plan to place more than one Gamoto on the same 1 bus it will be necessary to set each controller to a different address The complete address is constructed from three components the 2 device type fixed at 1001 with the exception of the broadcast case the Gamoto address set by dipswitches 3 4 5 and the Read Write bit O2Write 1 Read 2 Slave Address Byte 1 0 0 1 A2 Al AO R W Device Gamoto Address Read Write Use the following table to find the desired address A maximum of 8 controllers can be in use on the same bus due to this 1 C addressing limitation Note that the address used is different depending on whether you are readi
30. eds Note that for communicating with the Gamoto 400 kHz is the maximum speed that should be used Slave address of I2C device to whom we are talking DEFINE SLAVEID 0x90 Set this for your device z KKK KKK KKK KKK KKK KK KKK KKK KKK KKK KKK KKK KK KKK KKK KKK KKK KK KK KKK ko ko ko ko ko ko ko ko k ok MACRO DEFINITIONS Generic PIC Assembly macro definitions ifpos macro argl btfss argl 7 Test if argument is positive high bit clear endm ifneg macro argl btfsc argl 7 Test if argument is negative high bit set endm 0 macro bcf STATUS RP1 bef STATUS RPO endm bank1 macro bcf STATUS RP1 bsf STATUS RPO endm bank2 macro bsf STATUS RP1 bef STATUS RPO endm bank3 macro bsf STATUS RP1 bsf STATUS RPO endm I2C Routines using H W I2C Peripheral I2CInit NOTE I2C Pins must already be set to be INPUTS movlw 0x28 Set mode to I2C Master enable I2C movwf SSPCON 1 clrf SSPCON2 0x80 Clear status flags movlw 49 Set speed to 100kHz w 20MHz clock movwf SSPADD 0x80 bsf 55 5 0 80 5 Disable slew rate control set for 100kHz bcf 55 5 0 80 Set levels to I2C set if you want SMBus levels bcf PIR1 SSPIF Clear SSPIF interrupt flag bef PIR2 BCLIF Clear bus collision flag return 2005 Gamatronix Page 42 of 45 Gamoto Gamoto I2CWaitForI
31. efore attempting to use the Gamoto make sure the switches are set appropriately The factory default position is all switches in the OFF position Dip Switch Assignments Switch OFF ON Description 1 Cricket Bus Bus selection 2 19200 baud 9600 baud Serial baud rate 3 0 1 A2 Address bit 4 0 1 A1 Address bit 5 0 1 AO Address bit Note that the user must choose either or Cricket bus because they share the same I O pins on the controller The serial port uses different pins and can be used regardless of the bus selection position However i is not advisable to use the serial port while data is being sent received on the Cricket or IC bus because some of the same internal registers may conflict in this case The AO A1 and A2 address switches are used to set the Gamoto Address to a value from 0 to 7 The 2 Cricket Bus and Serial protocols use this address to determine which Gamoto is being addressed The table for setting this address is shown in the 2 protocol section Communication Protocols Serial The normal connection method for serial communications is to have one host connected to one Gamoto However the Gamoto is addressable to allow for a multi drop communication connection To connect more than one Gamoto to a single host PC or MCU you can simply connect the TX lines in parallel with the other TX lines and connect the RX lines to the other RX lines For more detailed inst
32. eleration for motion trajectory 208 00 3 X4 Relative distance for motion trajectory 211 D3 2 V4 Velocity for motion trajectory 213 D5 2 A4 Acceleration for motion trajectory 215 D7 3 5 Relative distance for motion trajectory 218 DA 2 V5 Velocity for motion trajectory 220 DC 2 A5 Acceleration for motion trajectory 2005 Gamatronix Page 23 of 45 Gamoto Gamoto 5 5 Mode Register The mode register is shown below It is a one byte register and each bit serves a different function as shown Care must be taken to avoid setting incompatible bits as not every combination is allowed The allowable modes and combinations are described in the paragraphs below Register Name MODE Address 0x2B R W 0 RO R W 0 R W 0 R W 0 R W 0 R W 0 R W 0 LAP PWM Over temp Brake PwrMode StopGrace VelMode TrajMode MpwrON Bit 7 6 5 4 3 2 1 Bit 0 bit 7 Locked Anti Phase PWM mode 1 LAP mode 0 Sign Magnitude PWM mode NOTE To change PWM mode you must first set clear the bit then save to Flash then power cycle the motor controller This only required for this particular Mode bit bit 6 Over temperature condition READ ONLY signal from H bridge 1 Over temp signal is active from H Bridge Motor is disabled and setPosition is set to mPosition so when condition clears motor will not jump 0 Normal condition bit 5 Brake On 1 Brake signal is being sent to H Bridge 0 N
33. g also shows the real time pulse width being received so it s handy for debugging your R C equipment T J 1 R C Pulse Timing Requirements T1 Minimum pulse width is 0 2ms Any smaller pulses will be rejected as noise T2 Normal pulse range is 0 2ms to 3 0ms Max and min are settable via MotoView T3 Time between pulses must be at least 20 usec 0 020ms There is no maximum If the signal is lost the set point will remain at the set point given by the last valid signal Note that in the current firmware version when using R C Pulse mode you must also enable Analog Feedback mode To set up this feature you need to set the following key parameters RCPmin RCPmax SPmin and SPmax These parameters are described by the diagram below Any R C Pulse that is shorter than the RCPmin value but greater than 0 2ms will be result in a set point of SPmin Similarly a pulse larger than RCPmax will result in a set point of SPmax RCPmin RCPmax Raw RIC Pulse Counts Converted to milliseconds SPmin SPmax If we take an example let s say you connect your R C radio receiver to the Gamoto open 2005 Gamatronix Page 10 of 45 Gamoto Gamoto the MotoView R C config dialog and look at the Raw R C pulse counts If you re getting values from say 4412 to 9762 then you could set RCPmin to 4500 and RCmax to 9700 Values outside of this range will get clipped to the max and min values Now you need to look
34. he lowest 8 bits are fractional The actual value to use for a given velocity depends upon your encoder resolution so this must be found by trial and error The actual algorithm for this mode is as follows SetVelocity is added to the target setPosition register every control cycle This means the target position is always changing but at a constant rate leading to a constant average velocity Be aware that if the motor is slowed by an obstacle and then freed it may temporarily speed up to catch up to the moving position target This leads to an accurate average velocity but not always the most stable instantaneous velocity 2 4 Trajectory Mode Mode Register 0000011 0x03 Enabled by setting the TrajMode bit of the Mode register This mode causes the Gamoto to immediately begin following the pre set trajectory that has been stored in the trajectory registers 2 4 1 Trajectory Stop Mode Register 0001011 0x0B Enabled by setting the StopGrace bit of the Mode register this allows the host to prematurely stop a trajectory in progress but rather than suddenly stopping the motor the motor is gracefully decelerated at the rate specified by the original trajectory This is useful when the distance to travel is not known ahead of time or an event triggers a necessary but not urgent stop Note this requires Trajectory Mode to be enabled and Velocity Mode disabled If there is no trajectory currently active setting this mode will
35. ing dS 256 Number of cycles over which average velocity is calculated For higher resolution encoders this number should be lower to prevent overrun of actual motor velocity register mVelocity For low resolution encoders increase this number This is also used to trigger the update of the trajectory variables A lower number updates more often 43 2B Mode 8 bit number Each bit enables or disables various modes For a complete description refer to section 3 1 Mode Register 2005 Gamatronix Page 19 of 45 Gamoto Gamoto 44 2C pwrLimit 8 bit number to limit maximum power delivered to the motor Set to 0 for zero power to motor 127 for 50 power and 255 for 100 power Normally set to 255 Use this to limit max voltage when using a lower voltage rated motor For example using a 12V battery with a 6V motor set this to 127 and the motor will never see more than the equivalent of 6 volts 45 2D Mode2 8 bit number Each bit enables or disables modes For complete description see section 3 2 Mode2 Register 47 2F setPosition 24 bit signed integer Can range from 8 388 608 to 8 388 607 This is the target position The error term is the difference between setPosition and mPosition 51 33 mPosition 24 bit signed integer Can range from 8 388 608 to 8 388 607 This is the actual motor position The error term is the difference between
36. ire risk for the results and performance of these libraries and tools is assumed by the purchaser Gamatronix does not warrant guarantee or make any representation regarding the use of this product No other warranties are made expressly or implied including but not limited to the implied warranties of merchantability and suitability of products for a particular purpose In no event will Gamatronix be held liable for additional damages including lost profits lost savings or other incidental or consequential damages arising from the use or inability to use Gamatronix s products or the products resold by Gamatronix Disclaimers Gamatronix reserves the right to make changes without notice to any product to improve reliability performance capabilities design or ease of use or to reduce size or cost Gamatronix products may not be used as components in life support devices of any description Copyright All the source code and documentation is covered under a Creative Commons license by Attribution The full text of the license can be found at www creativecommons org 2005 Gamatronix Page 4 of 45 Gamoto Gamoto Gamatronix Gamoto Integrated PID Servo Motor Controller Driver Gamoto Feature Summary O e 12 55 VDC Motor Voltage e 7 16 VDC Logic Voltage input e Integrated 3A continuous 6A peak H Bridge motor driver x 8 V B 7 16UDC Trapezoidal Trajectory processing for 4
37. istance is set to 10000 default e Velocity is set to 5000 default Acc set to 10 default TrajMode is set to 1 e SetPosition increases e Host program polls Trajectory Done bit until it changes to 0 now we know setPosition 10000 e Host position polls Error register 00 until Error 0 or Error lt AcceptableLevel e insert timeout behavior acceptable level window etc logic in this step Now we know we have arrived at the destination 4 2 Units of Measurement The units used to control and calculate the position velocity and acceleration are different than typical real world units To aid in the conversion to meaningful units this section describes how to do the conversions Some basic definitions CPR Counts per revolution counts rev This is how many encoder counts for every complete revolution of your output shaft or wheel To measure this value run MotoView and show the Register View window Display mPosition Turn your output shaft one turn and note how many counts have passed ORD One Revolution Distance inches rev feet rev etc This is the distance your device moves in one revolution in the distance units of your choice In the case of a wheel it s the circumference of the wheel To Period of Gamoto PID loop This is a fixed constant equal to 0 00051 seconds dS Number of PID cycles to skip when updating velocity Kd and profile information The factory default val
38. led It allows you to connect up to 8 Gamotos to the same serial TX and RX lines with no additional hardware other than a 10K pull up resistor which may be needed in some cases When this bit is set the Gamoto allows the TX line to float when it s not being used Since each Gamoto only replies to messages addressed to it by the correct header DIP switch combination then only the proper Gamoto will reply Since the TX line is floating when not in use a 10K pull up resistor is recommend if not already included in your serial transceiver or MCU 2 8 115200 Baud Rate Mode2 Register 00001000 0x08 This option enables serial communication at 115200 baud regardless of the dip switch settings for baud rate 9600 19200 Note that if you set this mode bit via a serial command the response will come back at the current baud rate it will not change to 115200 until you reset the Gamoto either manually or with a reset command 2 9 Step Direction Pulse Inputs Mode2 Register 00010000 0x10 This option enables command of the motor via Step and Direction signals similar to a stepper motor driver This allows you to use existing stepper motor driver software for example in CNC applications to control your DC servo motor The Step signal connects to J4 Pin 2 Normally the Lower Limit switch input and the Direction signal connects to J4 pin 3 Normally the Upper Limit switch input The limit switches are of course disabled while in this
39. ling the Gamoto in no time 2005 Gamatronix Page 31 of 45 Gamoto Gamoto 7 Mechanical Specifications The dimensions of the Gamoto board mounting holes are shown in the figure below Be careful when mounting the board to protect the bottom of the board from contact with metal surfaces that could short out the signals The board itself measures 2 75 in x 2 075 in The mounting holes are 0 15 inch diameter large enough for 4 40 or 6 40 screws 1 775 in 2 45 in 8 Electrical Considerations When designing your control system one of the first considerations is the power supply design In general it is desirable to separate digital control power from noisy high current motor power The Gamoto board allows this separation by having two separate connectors J8 is for logic power input and J2 is for Motor power connection However these supplies are isolated on the board by a voltage regulator so it is also possible to use one power connector for both and tie them together using jumper JP1 Separated power inputs When using two separate power inputs you can take advantage of higher motor voltages from 12V up to 55V for your motor You can also shut off or disconnect motor power without resetting the logic side of the motor board In this configuration the logic power can be from 7 5V to 16V DC Combined power inputs To combine power inputs install jumper JP1 With JP1 installed only one connector J2 must be used t
40. lly reset the Gamoto by pulling the reset line low momentarily 2005 Gamatronix Page 36 of 45 Gamoto Gamoto 9 8 J5 Serial Interface J5 Pin Serial Interface connector 1 G Signal Ground 2 Vreg Regulated 5 Volt supply output available to power a serial level adapter 3 RX Serial Receive line 5V logic levels 4 TX Serial Transmit line 5V logic levels This connector is used for controlling the Gamoto from a serial host such as a microcontroller MCU or PC When communicating using this port use the serial protocol as described in communication section of this manual NOTE You cannot directly connect a PC serial port to this connector because the logic levels are 5V levels not RS 232 or RS 485 levels A serial transceiver chip such as the Maxim MAX232 must be used in this case Either RS 232 or RS 485 transceivers may be used depending on the application If RS 485 is chosen you must use a transceiver capable of automatically enabling the driver upon transmission AutoDirection feature or similar name Two examples of this type of chip are the Maxim MAX13487E and MAX13488E devices See the Gamatronix website www gamatronix com for sources for off the shelf serial adapter cables to allow easy connection to a PC 9 9 J6 Encoder Inputs 6 Pin Quadrature Encoder inputs G 1 Ground Vreg 2 Regulated 5 VDC output Supplies power to LED for encoder A 3 Qua
41. ng or writing Gamoto Gamoto Write Read m s Address Address Address Address Binary Decimal OFF OFF OFF 000 0 0x90 0x91 OFF OFF ON 001 1 0x92 0x93 OFF ON OFF 010 2 0x94 0x95 OFF ON ON 011 3 0x96 0x97 ON OFF OFF 100 4 0x98 0x99 ON OFF ON 101 5 9 Ox9B ON ON OFF 110 6 0x9C Ox9D ON ON ON 111 7 Ox9E Ox9F All All All All Broadcast 0x00 N A Bold row represents the factory default configuration One the address byte is known sometimes called the Slave ID you can begin writing routines to control the Gamoto over the I C bus The last row is the Broadcast address or General Call which can be used to send commands to all Gamoto boards simultaneously This is convenient for starting two or motors at the same time Keep in mind however that it can only be used for commands writing not for reading since you wouldn t want two or more Gamotos responding at the same time 6 3 1 Example 2 byte Write to Kp register The basic sequence for a 2 byte write to a register is as follows shown here setting register Kp 0x1234 2 Example 2 byte write to Kp register Written in PIC Assembly I2C subroutines not shown JO S eutiE movlw SLAVEID call I2CWrite moviw 0x22 RegAddress Kp call Ire Send control byte W 2005 Gamatronix Page 28 of 45 Gamoto Gamoto moviw 0x34 cel 3052 81b movlw 0x12
42. ny write command to these registers will activate the command 2005 Gamatronix Page 18 of 45 Gamoto Gamoto 5 2 Register Memory Map Note All registers are stored with the LSB first MSB at the highest address Where noted some registers have a fractional component DEC HEX Register Len Description 00 FactoryRst 1 Writing to this special command register will cause all key registers 34 44 to be reset to factory default values See Appendix A for factory default values WARNING This command takes about 300 ms to execute If you execute this command during a trajectory move or while in velocity mode you may notice a slight jerk or hesitation in motion It is best not to issue this command while in velocity or trajectory mode 01 SaveParms Writing to this special command register will save all key registers to flash After this operation these values will survive a power cycle The key registers are locations 34 44 and all motion trajectory values WARNING This command takes about 300 ms to execute If you execute this command during a trajectory move or while in velocity mode you may notice a slight jerk or hesitation in motion It is best not to issue this command while in velocity or trajectory mode 02 Reset Writing to this special command register will reset the Gamoto just as if it were power cycled As with all command registers any dummy byte can be written to ac
43. o supply power DO NOT INSTALL JP1 WITH POWER CONNECTED TO BOTH CONNECTORS When combining the power inputs you are limited to a more narrow range of allowable voltages The acceptable range for combined power input is 12V 16V The advantage is a simpler cabling connector design and one switch can control the whole system REV E BOARDS ONLY One note about the fuse The fuse is only connected to the J2 connector so if you are using a single power connection use J2 not J8 Rev F and later boards do not have this problem Current Draw The typical standby current flow of the logic circuits is 40mA without encoders connected Depending on the type of encoders used this will increase to 80 to 110mA Note that with 2005 Gamatronix Page 32 of 45 Gamoto Gamoto high current encoders and high logic voltage supply i e 16VDC the 5V regulator will get quite warm and a heat sink is highly recommended Current draw for the motor side of the circuit is entirely dependent on the motor coil resistance and the torque applied on the motor shaft An easy way to estimate current is to measure the motor winding resistance and divide this into the motor voltage you plan to use Make sure the estimated current is less than 3 Amps before connecting it to the Gamoto An example calculation is as follows Motor winding resistance measures 6 ohms and you plan to use a 12V battery Since batteries usually charge higher than their nominal voltage le
44. on the same bus then you also need to set each address differently so they don t conflict The Cricket communication protocol format is shown below All Cricket messages start with a special 9 bit Cricket Command code The next byte is the RW Address byte that tells if the operation is a Read or a Write and includes the 3 bit unit address of that particular Gamoto controller The 3 bits allow for up to seven Gamotos on the same Cricket bus The next byte is the RegNum or register number that specifies which register is the target of the read or write In the case of a write Bytes to Write and Data to be written follows Cricket READ format 2005 Gamatronix Page 29 of 45 Gamoto Gamoto 1 CrktCMD RW Address RegNum data1 data2 Cricket WRITE format CrktCMD RW Address RegNum Bytes to Write data1 data2 6 4 4 The Cricket Command Word 1 0 0 1 0 0 1 0 CMD bit Cricket Class ID Always 7 11 for Gamoto devices The best way to think of the Cricket Command Word is that it is always written as 100 11 for the Gamoto devices The 100 signals a command and the 11 is the Cricket Class ID that has been assigned to Gamoto devices That s all you need to know to use the Gamoto with Crickets If you are implementing a Cricket Bus yourself using a non cricket controller then you may need to understand more of the protocol det
45. or operates in the wrong direction reverse these leads IMPORTANT NOTE MOTOR POWER MUST BE AT LEAST 12 VOLTS FOR THE H BRIDGE TO WORK PROPERLY LOWER VOLTAGES WILL CAUSE STRANGE BEHAVIOR THAT IS DIFFICULT TO TROUBLESHOOT SO ALWAYS CONFIRM MOTOR VOLTAGE IN CASE OF ODD BEHAVIOR If you do not want to use 12V or more because your motor is rated for a lower voltage then refer to the register descriptions on pwrLimit This will allow you to use a lower voltage motor 9 6 J3 Cricket Bus connector J3 Pin Cricket Bus Connector G 1 Ground Vcc 2 Regulated 5VDC power supply Use jumper JP 12 to disconnect this Bus 3 Bus data line This is normally high low when active or during init signal V 4 Unregulated voltage supply 2005 Gamatronix Page 35 of 45 Gamoto Gamoto Handy Cricket Bus Jack gt Unregulated power output Bus signal Logic power output Gnd top view looking down at Cricket s Bus receptacle This port can used to connect the Gamoto to a Handy Cricket or other Cricket Bus enabled device A second optional pigtail connector is hooked in parallel to this one for easy daisy chaining of bus devices For more details on the Cricket Bus connector and protocol see http Awww handyboard com cricket tech bus shtml 9 7 J4 Limit Switch Inputs and Reset J4 Pin Limit Switch Inputs and Reset line G 1 Ground LL 2 Lower Limit switch input
46. ormal condition bit 4 PwrMode 0 Power Mode is Disabled In this state the PID loop operates normally and the mPower register is ignored 1 Power Mode is Enabled In this state the PID loop is bypassed and the motor power is taken directly from the mPower register Encoder position is tracked but ignored bit 3 StopGrace 0 Disabled 1 Enabled When this bit is set during a trajectory move the Gamoto immediately starts decelerating until completely stopped using the deceleration rate that is stored in the trajectory This is only valid when TrajMode is set bit 2 VelMode 0 Disabled 1 Enabled When this bit is set the SetVelocity register is used as a velocity set point Use this when you want to control the velocity rather than absolute position The PID loop will continually add this value to the Position target register This moving target position value causes a constant average velocity This is only valid when TrajMode is disabled bit 1 TrajMode 0 Disabled 1 Enabled When this bit is set the Gamoto immediately begins following the pre loaded trajectory When the trajectory has been completed this bit is automatically cleared Poll this bit to find out when the move has been completed bit 0 MpwrON 0 Disabled Motor will not receive power without this bit set 1 Enabled When this bit is set the enable pin on the H Bridge is set allowing power to flow to the motor This bit is independent of all other mode set
47. power for the digital components G 1 Ground V 2 7 5 16 VDC Typical current consumption is 40 mA 12V G 3 Ground Although this is a three position connector only one ground connection is necessary The third pin has been added to help prevent accidentally reversing the input power We recommend using a three pin connector for power because it allows the user to connect in either orientation without risk of damaging the board WARNING There is NO internal protection against reverse polarity so if power is connected backwards the 5V regulator WILL be permanently damaged The good news is that this is a commonly available part and not too difficult to replace if you have a solder iron and some electronic experience The Digikey part number is LM340T 5 0 ND but many substitutes can be used such as the LM7805 2005 Gamatronix Page 39 of 45 Gamoto 3994S 0 91 60 002 0 F120 Aq 104 4equnwN iueunoo FON J9 O1JUOD JOJO SIAN 2180119 ayevedas 0 10151581 0487 2 NI 0028 W e2 ES Ms AME Bite ee aug me loos TvAB3HL SA 24 05 sou ods 924 204 85 cad rau sgy 10 Schematic Diagram Gamoto 28 29 493 25
48. r can communicate with the Gamoto in any one of three ways Serial or Cricket Bus Serial communication uses a simple binary based protocol with a header and checksum to reduce errors As an slave device the Gamoto accepts read and write commands to its internal registers as well as some special commands allowing full control over the Gamoto Maximum speed is 400 kHz The third communication option is the Cricket Bus This is a one wire serial type of 2005 Gamatronix Page 5 of 45 Gamoto Gamoto interface similar to IC but using only one signal line plus power and ground This bus is designed with Handy Cricket devices www handyboard com cricket but since it is an open protocol any host controller can implement this bus and use it to communicate with the Gamoto 1 1 Technical Specifications Processor PIC16F876 20 MHz H Bridge LM18200 DMOS Quad H Bridge Motor Voltage input 12 55 VDC Motor Current output 3A continuous 6A peak Logic Voltage input 7 16 VDC Position Registers 32 bit signed with 8 bit fraction PID Constant Registers 16 bit signed PWM Resolution 10 bit resolution PWM Frequency 19 54 kHz Trajectory Storage 6 trajectories storable in non volatile flash Analog inputs 4 user analog inputs 10 bit resolution 1 for motor current Digital inputs Upper limit Lower limit switches interlocks motion Over current protection 5A replaceable f
49. ructions on this refer to this guide available on the Gamatronix website http www gamatronix com gamoto examples Serial 20Share 20how to pdf On the protocol level allowing multiple Gamotos requires that you specify which Gamoto you are speaking to Gamoto Address This is specified by setting the dipswitches as with the and Adae protocols Please refer to the IC communication section to see how to set the Gamoto Address 0 7 This Address is added to hex value AA and becomes the header byte of the packet Examples of the different types of transactions are shown below For the most common case of RS 232 Serial with only one Gamoto simply leave the dipswitch set to the factory positions and use a header value of AA The checksum is a single unsigned byte and is calculated by using a simple sum of the preceding bytes excluding the header and the checksum byte itself In the case of the checksum totaling more than 255 it rolls over wraps as necessary An example of the formula in Visual Basic is CSbyte bytel byte2 byte3 byte4 mod 256 2005 Gamatronix Page 26 of 45 Gamoto Gamoto 6 2 1 Example Write 1234 to Kp Register Header LEN RegNum Data LSB Data MSB CHECKSUM AA 0 to 7 03 22 34 12 lt Length gt lt CHECKSUM gt The serial protocol is bina
50. ry coded with a header and checksum to help ensure reliable data transfer The example diagram above shows a two byte write to the Kp register The Header byte which is dependent on the dipswitch setting is followed by the RW Length byte The high bit of this byte is 0 for Writes 1 for Reads The lower nibble indicates the length of information to follow excluding the Checksum byte The next byte is the target register address followed by data bytes and then a checksum The checksum does not include the header or the checksum byte itself The number of data bytes is flexible up to a maximum total message size of 8 bytes This means the maximum continuous bytes you can write to a register location is 4 bytes This allows you to access any register with a single transaction 6 2 2 Example Write Response ACK CHECKSUM 41 41 The reply from the Gamoto is shown above In place of the header is an ACK byte which should always be 41 If this is different then there was some internal error 6 2 3 Example Read from Kp Register Node LEN RegNum NumBytes CHECKSUM AA 0 to 7 82 22 02 A6 lt Len gt lt Checksum gt The read is same in structure as the write with the main difference in the high bit of the RW Len byte The high bit is one indicating a read and the data following the register number is th
51. setPosition and mPosition 54 36 setVelocity 16 bit signed integer specifying desired velocity This number divided by 256 is added to the target position setPosition every dS period For example if dS 10 then every 10 control cycle setVelocity 256 is added to setPosition 57 39 mVelocity This is a signed 16 bit number that represents the actual motor velocity totaled over several dS cycles The velocity is calculated as the change in encoder counts in a given time period To change the scaling of this number dS can be adjusted mVelocity is also the multiplier for Kd used to calculate the derivative term for the control loop so changing dS will have a direct effect on the strength of the derivative term 59 3B trajectory The trajectory register is used to choose which trajectory you would like to run To run a given trajectory first store the desired distance velocity and acceleration in one of the 7 trajectory register sets Then specify which trajectory register set you want to run by writing to trajectory Then turn on trajectory mode by writing the proper mode command to the Mode register 60 3C mPower Motor power Signed 8 bit number Used normally in open loop mode without encoders or when you want manual control over actual voltage delivered to the motor Setting mPower 0 will cause motor to stop Setting mPower 64 will cause 5096 forward power Setting mPower
52. t s assume 13 volts for the calculation So current 13 6 2 17 Amps This is less than 3 A so it should work fine with the Gamoto 9 Connector Pinouts This section shows connector pin assignments and electrical details required for interfacing the Gamoto to your application The connectors are labeled JP1 to JP10 as printed on the PC board s silkscreen Over temp LED Fuse Blown LED J8 Power LED 39 JP1 J5 46 JP3 9 1 LED Indicators The Gamoto board has three LED indicators A green power LED D4 lights when logic power is present A yellow Over Temp LED lights when the H Bridge indicates it is in temperature shutdown mode A red Fuse Blown LED D2 lights when the fuse is removed or blown 2005 Gamatronix Page 33 of 45 Gamoto Gamoto 9 2 Fuses There is one removable fuse on the Gamoto labeled FS1 in the upper right corner of the board If this fuse is damaged or removed the red fuse LED will light The Gamoto ships with 5A fuse in this position but you can change this value if you like The ordering information for additional fuses is shown here Fuse Type Digikey P N 1 0 Amp Fast acting WK3048BK ND 1 25 Amp Fast acting WK3050BK ND 1 6 Amp Fast acting WK3053BK ND 2 0 Amp Fast acting WK3057BK ND 2 5 Amp Fast acting WK3058BK ND 3 15 Amp Fast acting WK3024BK ND 4 0 Amp Fast acting WKS3062BK ND 5 0 Amp Fast acting WK3063BK ND 9
53. t worry about the Brake For most cases you won t ever need to set it or read it or understand it The one exception is the case where you really want to free spin your motor with no power In this case send zero power and turn on the brake bit 4 Theory of Operation The Gamoto motor controller uses a PID Proportional Integral and Derivative algorithm to calculate how much power to deliver to the motor and in which direction This is nota new technique It was developed in the 1960 s and is still the accepted standard today for fast accurate motion control as well as most other types of control systems The main equation has three major components the sum of which equals the power to be delivered to the motor The inputs to the equation are the set point setPosition register the actual position mPosition register and the three key constants Kp Ki and Kd the proportional integral and derivative constants respectively We can calculate the error u by subtracting the set point from the actual position 1 u mPosition setPosition The Proportional component is straightforward 2 Kp xu The Integral component is calculated based on the integral over time of the error 3 Ki x Judt The Derivative component is calculated based on the differential the actual position over time which in the case of motor control is the same as the velocity mVelocity register 4 Kd x mVelocity 2005 G
54. tings 2005 Gamatronix Page 24 of 45 Gamoto Gamoto 5 6 Mode2 Register The Mode2 register is shown below It is a one byte register and each bit serves different function as shown Care must be taken to avoid setting incompatible bits as not every combination is allowed The allowable modes and combinations are described in the paragraphs below Register Name MODE2 Address 0x2D R W 0 R W 0 RW 0 RN 0 R W 0 R W 0 R C Pulse Analog Step 115200 reserved Enable Feedback Direction baud SerialShare MotionDone Homing Bit 7 6 5 4 3 2 1 Bit 0 bit 7 Reserved for future use bit 6 R C Pulse Input Enable 1 enabled 0 disabled bit 5 Analog Feedback Enable 1 enabled 0 disabled bit 4 Step Direction Pulse Input Enable 1 enabled 0 disabled bit 3 115200 Baud Rate Enable 1 enabled 0 disabled bit 2 SerialShare Enable 1 Serial Share enabled 0 SerialShare disabled bit 1 MotionDone Enable 1 enabled 0 disabled bit 0 Homing Mode 1 Homing Mode enabled 0 Homing Mode disabled 6 Communication Protocols There are three ways to communicate with the Gamoto Serial I C bus or Cricket Bus All of them require setting checking the dipswitch settings for configuration 2005 Gamatronix Page 25 of 45 Gamoto Gamoto 6 1 6 2 Dip Switch Settings The table below shows the dip switch assignments and the purpose of each of the switches B
55. tivate the command 03 SetHome Writing to this special command register will set the mPosition and setPosition registers to zero effectively making the current position Home The current Mode is not changed 34 22 Kp Kp is the proportional constant register used to scale the overall response of the system Kp is multiplied by the position error Signed 16 bit number Can range from 32768 to 32767 but negative numbers should not be used for this register 36 24 Ki Ki is the integral constant register used compensate for steady state error in the system Ki is multiplied by the integral of the position error Signed 16 bit number Can range from 32768 to 32767 but negative numbers should not be used for this register 38 26 Kd Kd is the derivative constant register used to compensate for overshoot in the system Kd is multiplied by the derivative of the position error Signed 16 bit number Can range from 32768 to 32767 40 28 iLimit iL integration Limit is used to limit the maximum build up of integral error Prevents integral windup problems when a long lasting steady state error causes excessive build up of the integral term Signed 16 bit number Can range from 32768 to 32767 but negative numbers should not be used for this register 42 2A dS Unsigned 8 bit number Can range from 1 to 255 Setting this to 0 has the effect of sett
56. uce the amount of coasting or free wheeling after a controlled move The second confusing part of the braking behavior is the way that the H Bridge has implemented the brake The data sheet states that to assert the brake you not only need to set the Brake pin high but also set the PWM input high The PWM input normally tells the motor to turn on So in the case of the Gamoto you would need to turn on the Brake bit of the Mode byte then command the motor to go at full power set PwrMode of Mode byte then set mPower 127 in order to activate the brake This actually works the motor does not turn and has a noticeable resistance to turning in this condition But there is a better way The third confusing part of the behavior actually allows a more convenient way to use the brake According to the H bridge datasheet if the brake pin is Low disabled while the PWM pin is low no command for power then the braking is actually ON This means that during normal operation when you signal zero power to the motor the braking is activated This actually makes sense because if you want zero power you generally want to stop If for some reason you want to stop and coast then you ask for zero power and then turn ON the Brake bit Note that as long as the Brake bit is on it cannot be controlled by the Gamoto so if it slips away from its setPosition it will not drive back to set point until the Brake bit is turned off Bottom line Don
57. ue is 10 but this is changeable by the user V Velocity This can be represented in many units as shown below The basic unit is the internal Gamoto units which are in relation to the PID loop of the Gamoto 2005 Gamatronix Page 15 of 45 Gamoto Gamoto 4 2 1 Velocity Equations v V counts sec 256 To 45 V inches sec V counts sec ORD CPR assuming ORD is in inches rev V miles hour V in inches sec 5 88 Example calculation We have a robot with 3 diameter wheels driven by a motor with 19 1 gear reduction The encoders have 250 counts rev and are attached to the motor before the gear reduction First the CPR of the output shaft 250 19 4750 counts rev The ORD circumference of the wheel or pi D or 3 14159 3 9 42 inches rev When using MotoView we enter a set velocity 8000 and dS 10 How fast is the motor going V 8000 256 0 00051 10 6127 5 counts sec V V counts sec ORD CPR 6127 5 9 42 4750 12 15 inches sec V V in inches sec 5 88 12 15 5 88 0 69 miles hour 4 2 2 Acceleration Equations A 256 To dS A cnts sec inches sec A ORD CPR A relative to gravitational constant 0 inches sec 12 32 2 Example calculation If we continue the above example let s find out how fast an acceleration setting of 20 will cause the robot to accelerate A 20 256
58. use with LED indication of failure Over temp protection Over temp LED auto shutdown H bridge Encoder inputs Filtered up to 254 000 counts sec Parameter storage Key parameters stored in non volatile flash Serial Interface 9600 or 19200 baud serial command protocol 2 Interface Operates as an 12 slave with command protocol Cricket Bus interface Complies with Cricket device bus for use with Handy Cricket R C Pulse Capture 0 3ms pulse width with configurable hi low set points Step Direction inputs 5V Digital pulse capture triggers on positive edge of Step pulse signal 2005 Gamatronix Page 6 of 45 Gamoto Gamoto 1 1 Typical Application Shown below is a block diagram of a typical application Serial or 12C or CricketBus A PC can connect using serial COM port and a serial level shifter such as the Maxim MAX232 2 Operational Modes The Gamoto can be operated in any of several operational modes The mode setting can be changed on the fly by the host during operation or the power on default mode can be customized allowing it to always power up in the desired mode For details of the actual Mode registers see section xx The various modes are outlined below 2 1 Position Mode Mode Register 00000001 0x01 This is the default mode in which the motor drives to the set position stored in the setPosition register On power up
59. ut 3 Scale is 0 5V with 10 bit resolution making the register minimum 0 maximum 1023 168 A8 Analog4 2 Analog input 4 Scale is 0 5V with 10 bit resolution making the register minimum 0 maximum 1023 2005 Gamatronix Page 22 of 45 Gamoto Gamoto 5 4 Motion Trajectory Registers The motion trajectory registers are shown below The all begin with LSB first as with all registers The distance register is three bytes 24 bits and the others are 2 bytes 16 bits You can store up to six motion trajectories in this memory space and they can be saved in non volatile flash memory if desired see the SaveParms command To calculate the address of a motion profile register where n 0 to 5 X n 180 n 7 V n 183 n 7 A n 185 n 7 DEC HEX Length Register Description 180 B4 3 Relative distance for motion trajectory 183 B7 2 VO Velocity for motion trajectory 185 B9 2 AO Acceleration for motion trajectory 187 BB 3 1 Relative distance for motion trajectory 190 BE 2 V1 Velocity for motion trajectory 192 2 A1 Acceleration for motion trajectory 194 C2 3 X2 Relative distance for motion trajectory 197 5 2 V2 Velocity for motion trajectory 199 C7 2 A2 Acceleration for motion trajectory 201 C9 3 X3 Relative distance for motion trajectory 204 CC 2 V3 Velocity for motion trajectory 206 CE 2 A3 Acc

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