67A Hall Effect Joystick I2C User Manual
Contents
1. 67A Hall Effect Joystick 12C User Manual rev 1 0 67A Hall Effect Joystick I2C User Manual Features e Proportional digital output e Shaft and panel seal to IP67 e Compact 1 inch square flange e Minimal 0 73 inch depth behind panel e Long operational life gt 1 million cycles Applications e Medical e Material handling vehicles e Mobile electronics for outdoor use 1 Introduction The 67A joystick is a proportional output joystick which provides an X Y coordinate approx 0 80 proportional to the joystick location The X Y coordinates are read from the joystick via an C bus Features include Proportional Joystick C Interface other interfaces available Low Operating Current 3 mA max Vpp 3 3V Low Power Sleep Mode 100 WA max Vpp 3 3V 2 Hardware Interface 2 1 Connector Two options are available header or ribbon cable with connector A Ribbon cable with Tyco 7 215083 6 connector Mating header Tyco 7 215079 6 B Header 1x6 0 05 centers with 0 025 sq pins Pin Signal IO Description C Data Line 2 Power Supply 3 0V 3 6VDC 3 Ground o a Vss __ Ground in 4 IC Clock Line Interrupt Out Open Drain Active Low 6 A1n in A1n LSB of 7 bit fC address Table 1 67A Connector Signals 67A Hall Effect Joystick 12C User Manual rev 1 0 The 67A is an I C Slave with 7 bit I C address of 80h A1n floating or 82h Ain tied to Gnd I C sp2. art I2C Address R W ACK Control Reg Value 76h ACK Data 9Ah ACK Stop 4 4 1 FIG 3 Send Reset Command over I C Bus Power Modes amp Sleep Threshold Power Up Sequence During a power up once the power supply voltage reaches 3 0V the user must wait the Nominal Startup Time Tp w before communicating with the joystick over the C bus also applies to a reset joystick command At the end of the Nominal Wakeup Time the 67A generates the first pair of XY values and sets INTn low Thereafter INTn goes low only if the X or Y value changes FIG 4 Power Up Sequence 4 2 4 3 67A Hall Effect Joystick 12C User Manual rev 1 0 Full Power Mode In this mode an internal measurement occurs every 20 ms If the X or Y value changes from the last values ouptut the INTn output Pin 5 is set low signaling new X amp Y values are ready to be read INTn is cleared Hi Z while the Y value is read Power consumption is higher in this mode As long as the joystick position is outside of the Sleep Zone it will operate in this mode Low Power Sleep Mode When the joystick position for both X and Y is within a circle defined as the Sleep Zone for ten consecutive measurements the joystick goes to the Low Power mode where power is significantly lower The Sleep Zone typically extends to a joystick shaft angle of 5 from the center See Fig 6 The last XY value output before entering the Low Power mode is 0 0 A
3. e requirement TSU DAT 250 ns must then be met This will automatically be the case if the device does not stretch the low period of the SCL signal If such a device does stretch the low period of the SCL signal it must output the next data bit to the SDA line TR max TSU DAT 1000 250 1250 ns according to the Standard mode 2C bus specification before the SCL line is released 5 1 1 Clock Stretching As mentioned previously the I2C Master that interfaces with the joystick must be capable of clock stretching on a byte level The joystick is able to transmit a byte of data at a fast rate but may need more time to prepare the next byte to be transmitted The joystick slave holds the SCL line LOW after transmission and acknowledgment of a byte to force the master into a wait state until the slave is ready for the next byte transfer in a type of handshake procedure See Fig 8 below See IC Spec UM10204 Rev 3 Sec 3 9 for more on clock stretching tM Toe gt st GT GHG HG L FL Start I2C Address or Data ACK E Data FIG 8 Clock Stretching by Joystick Revision History Description of Changes 07 25 12 Initial Version Started from V2 3 of Electrical Spec 9 18 12 1 1 SAK Replaced Fig 6 Joystick Output vs Shaft Angle with more accurate graph and changed graph labels 9 19 12 Corrected Fig 5 graphic a es 10
4. e temperature Table 4 Operating alta Parameter a Tve f so foal as Pv a va V High level input voltage 0 25 Vpp ee Low level input voltage Vss lt VpIN lt Vop Pin at INTn SDA arene a o 28 s0 ma peso coe vp Current Consumption Low Power p Average current Vpp pin sleep mode Vpp 3 3V DDA Note 3 Measurement Frequency Full Sample Power mode s sec Response Time Full Power Mode 2 ms Note Response Time Low Power Mode lt ee Output with Joystick Released Une or Units Center a Low Power Sleep Threshold Power Low Power Sleep Threshold Threshold Nominal Startup Time EOT a ee eT Operating temperature range Note 1 Positive value is for movement in the positive X or Y direction Negative value is for movement in the negative X or Y direction Positive Y direction is indicated by the A symbol on the joystick case Note 2 Response time is the time from joystick movement to when new X Y position data is available INTn goes low Note 3 For VDD lt 2 9V current will exceed 100 uA Note 4 Max values along X or Y axis in positive and negative directions 67A Hall Effect Joystick 12C User Manual rev 1 0 5 1 1 C Bus Timing Requirements Tsu sta P 3 Tup pat gt lt gt Tao 2 gt lt Tuo STO gt Tostra Tsu sto SDA out FIG 7 C Bus Data Requirements Table 5 I C Bus Data ee Param
5. eed up to 400 KHz External pull up resistors are required for I C signals SDA amp SCL See Sec 2 3 for recommended pull up resistors for I C signals and INTn Recommended value 2K 10k See Fig 1 INTn Interrupt Out Active Low Goes low only when a different X Y value is available Reading the Y value causes INTn to go high inactive For most efficient use of the I C bus and processor resources it is recommended that the INTn signal be used to trigger reading of the X Y value from the joystick If INTn is not used X Y values should be read continuously at a rate of 50 samples sec An external pull up resistor in the range of 2K 10K see Fig 1 is required for INTn 67A JOYSTICK VDD Q Hall Effect Sensor JUMPER OUT 80H JUMPER IN 82H PULL UP RESISTORS REQUIRED FIG 1 67A Electrical Connection Diagram 2 2 Cable PCB Trace Length Cable PCB Trace Length Varies with I C frequency The I C Spec specifies a max capacitance per signal line SCL or SDA of 400 pF The bus capacitance is the total of wire PCB traces and pins The longer the cable PCB trace length the higher the bus capacitance and thus the lower the operating frequency that can be used 2 3 Pull up Resistors 2 3 1 I C Signals SCL SDA Pull up Resistors The two I7C signals SDA amp SCL must be pulled up to the power supply voltage at the Host CPU The pull up resistor value depend on the bus capacitance and SCL frequenc
6. eter Start condition 100 kHz mode Hold time 400 kHz mode 100 kHz mode Setup time Stop condition 100 kHz mode Hold time 100 kHz mode Clock high time 100 kHz mode Clock low time SDA and SCL rise 400 kHz mode 400 kHz mode mode 400 kHz mode kHz mode T HIGH 400 kHz mode oe T HIGH 400 kHz mode kHz mode oe kHz mode time eee kHz mode SDA and SCL fall time eoo kHz mode 100 kHz mode kHz mode 100 kHz mode Data input hold time T HD DAT 400 kHz mode kHz mode Data input setup aoa kHz mode TUDAT time 400 kHz mode 400 kHz mode mode 400 kHz mode 400 kHz mode mode Output valid from 100 kHz mode clock 100 kHz mode Bus free time 400 kHz mode kHz mode EA Power SCL delay from Mode Clock Stretching Bus capacitive loading oe l Power oe l Co e e C aa Se ee 0 1CB tierce is specified to be from 10 400 pF Note After this period the first clock pulse is generated CB is a 4 to be from 10 400 ee s Bot the bus must be free before a new transmission can start Note 1 As a transmitter the device must provide this internal minimum delay time to bridge the undefined region min 300 ns of the falling edge of SCL to avoid unintended generation of Start or Stop conditions 67A Hall Effect Joystick 12C User Manual rev 1 0 Note 2 A Fast mode 400 kHz I C bus device can be used in a Standard mode 100 kHz C bus system but th
7. g of the read of the Y value see Fig 2 C Start Command 81h or 83h Joystick I C Address with DO set for read X Byte Data from Joystick 1 Byte Data from Joystick C Stop Command Important Note If anew X amp Y value is available before the previous values are read the new values will over write the old with the loss of the oldest values However in order to keep the X 6 Y values paired together or in sync it is important that the user read the X amp Y values in the a single I C sequence as shown in Fig 2 This is also the fastest and most efficient use of the IC bus 67A Hall Effect Joystick 12C User Manual rev 1 0 SCL SDA Start I2C Address RW ACK X Reg Value ACK Y Reg Value ACK Stop INTn FIG 2 Read X amp Y Values over I C Bus 3 2 2 Reset Joystick To reset the joystick the I C Master should perform a write sequence of 1 byte SC and must provide the register address for Control Reg C Start Command 80h or 82h Joystick 1 C Address with DO low for write 76h Register Address for Control Reg 9Ah Data C Stop Command Note after sending the reset command the I C Master must wait 300 ms before attempting to access the 67A At the end of the Nominal Startup Time Tpw the 67A generates the first XY pair of values and sets INTn low Thereafter INTn goes low only if the X or Y value changes t GEE EEE LG E e Ute eee ULE EMM ed DEM le St
8. gister so that X register value can be read without writing to register pointer See Sec 3 2 IMPORTANT In order to keep X amp Y values paired together or in synch X register data should be read in an I2C sequence which reads both the X amp Y registers as described in Sec 3 2 1 and Fig 2 3 1 2 Y Register Y 3 R R R R R R R R Reset value 0000 0000 e Bit7 0 Y coordinate Y coordinate 2 s complement format signed 128 to 127 Reading the Y register will reset INTn output to Hi Z The Y register should be read in a single I2C sequence that reads the X Register first immediately followed by the Y register as described in Sec 3 2 1 and Fig 2 3 1 3 Control Reg 76h e 1 E x N x X Do Not Care Reset value 1001 1010 9Ah Writing to this register with Reset Bit 1 high resets joystick and sets all registers to default values The Reset bit is set low by the joystick after completing the reset sequence Note there is a start up time Tpw which must be observed after resetting the joystick 3 2 1 C Read and Write Cycles 3 2 1 Read X amp Y Values When INTn goes low there are new X amp Y values available To read the X amp Y values the external I C Master should perform a read sequence of 2 bytes without providing a register address Joystick always sends X register value followed by Y register value for any 2 byte read without a register address INTn will go high inactive at the beginnin
9. p then a reset command needs to be sent to the joystick to make active the new value Ain is only read by the joystick after a power up or reset command Changing the I C address would be necessary if two 67A joysticks are connected to the same I C bus or if another component connected to the IC bus shared the same I C address To request a custom I C address contact Grayhill SDA is a bi directional signal and is used to read and write the serial data The SCL signal is the clock generated by the host CPU to synchronize the SDA data in read and write mode The maximum I C clock frequency is 400 KHz with data triggered on the rising edge of SCL Clock Stretching Clock stretching occurs when a device on the bus holds the SCL line low effectively pausing communication The joystick slave may stretch the clock to allow more time to load data to be read by the master device It is important that the IC Master interfacing with the 67A implement clock stretching on a byte level for reliable operation with the joystick See Sec 5 1 1 for more on clock stretching 3 1 I C Registers 3 1 1 X Register X 7 sign X 6 MSB X 5 X 4 X 3 X 2 X 1 X0 LSB R R R R R R R R 67A Hall Effect Joystick 12C User Manual rev 1 0 Reset value 0000 0000 e Bit7 0 X coordinate X coordinate 2 s complement format signed 128 to 127 Note After every complete I C transaction the register pointer in the joystick is set to point at the X re
10. s long as the joystick remains within the circle defined by the threshold the joystick will remain in the Low Power Mode and INTn will stay high When the joystick is moved outside of the Sleep Zone circle it returns to the Full Power mode new XY measurements are available every 20 ms and power consumption increases Low Power Sleep Mode current may be higher if supply voltage drops below 2 9V FY 80 0 X MAX JOYSTICK OUTPUT 0 80 o LOW POWER SLEEP ZONE ALL VALUES 0 0 FIG 5 Sleep Zone amp Max Output Circle Output Along X X Y or Y Axis 90 80 70 60 50 40 30 20 10 67A Hall Effect Joystick 12C User Manual 2 4 6 8 10 12 14 16 18 Shaft Angle Deg FIG 6 Joystick Output Along X or Y Axis vs Shaft Angle Typical 20 22 rev 1 0 67A Hall Effect Joystick 12C User Manual rev 1 0 5 SPECIFICATIONS NOTICE Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device This is a stress rating only and functional operation of the device above those listed in the operation listings of this specification is not implied Exposure above maximum ratings conditions for extended periods may affect device reliability Table 3 Absolute Maximum Ratings non operating Parameter i i Note DC Supply Voltage Voltage on all other pins with respect to Vss Max current sunk by any I O pin Storag
11. y See Table 2 below for recommended pull up resistor values vs SCL frequency and bus capacitance 67A Hall Effect Joystick 12C User Manual rev 1 0 Rp recommended Bus Load Capacitance SCL Frequency 100 pF 200 pF 300 pF 400 pF Standard Mode 100 KHz 6 49KQ 3 48KQ 2 2 49KQ_ 2KQ Fast Mode 400 KHz aKa Sako Table 2 Recommended Pull up Resistors for SCL SDA vs Frequency amp Bus Capacitance To determine if a proper pull up value is being check the low and high voltage levels for SCL and SDA during I C bus activity The signal levels should meet the following requirements with at least a 0 1V margin Vi max lt 0 3 Vbo Vu min gt 0 7 Vop For more on choosing the I C pull up resistors see Sec 7 1 in 2C bus specification and user manual Rev 03 NXP UM10204 2 3 2 INTn Pull up Resistor The pull up for the INTn signal should be between 2K 10KQ 3 1 C Interface The 67A joystick communicates over an C bus 2 wire bi directional serial interface The host CPU master must initiate the data transfers as the 67A is a slave device lC address The C address consists of 7 bits D7 D1 and a bit DO indicating whether it is a Read 1 or Write 0 cycle The 67A is shipped from the factory with the 7 bit device I C address of 80H 1000 000X when A1n pin 6 is left floating not connected The IC address may be changed to 82H by pulling A1n to Gnd If Ain is changed after power u
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