Servo controller manual
Contents
1. User s Manual SSC ASD2 v2 1 07 00 pg 1 Mini SSC II Serial Servo Controller The Mini SSC II is an electronic module that controls eight pulse proportional hobby servos according to instructions received serially at 2400 or 9600 baud Two Mini SSC II units can share the same serial lineto control a total of 16 servos This addressability is expandable you can order units programmed with other ranges of servo addresses so that a total of up to 32 Mini SSC IIs controlling up to 255 servos can share a single serial line Table of Contents Connections and Configuration JUMPELS ccceeceeteeeeeeeeneeceaeeeeeeeeaeeseeeeeaeesaeseaeesseeeeeeeneeenaees 2 Configuring the Mini SSC Ul ee eee ceceseeeeseeeeseeeneeeeseeeeeeeeseeseaeeeaeesaeeeeensaeesaeseaeessaeseeesneneenaes 2 Connecting the Mini SSG Il vi ctiteceiey lied evet iene EEE E e 3 Initial CHECKOUT i ssteasictestihateneeecsahaee aaa aar E aaa e a aa aaa aE aaee eR 5 Programming for the Mini SSC Il i eee eeeeeceeeeeeeeeeneeeeeeeeaeeeeeseaeeeeeeeeeeseeeeeaeeseaeeeneeseaeeseeeeeaees 5 Multiple Mini SSCS s h08 dena ait ete det cei Nee eleip ain ali A te eee 5 Theory Of Operation 225 2 55 a ea aa chats suleadaagzandestentacejaysesdshenscacadhansatsestashazadacetansatace 6 Program Example Senir ana ea Pavoni int aa Ao ee Bae 7 Disclaimer of Liability Scott Edwards Electronics Inc is not responsible for any special incidental or consequential2. R ange With no jumper at R the Mini SSC II controls servos over a 90 range of motion Servos positions are expressed in units from 0 to 254 so each unit corresponds to a 0 36 change in the servo s position With a jumper at R the Mini SSC II controls servos over as much as 180 with each unit corresponding to a 0 72 change in position 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 3 Configuring the Mini SSC II continued Note Regarding Range Some servos cannot move through a 180 range They may stall when positions less than 50 or greater than 200 are used with the Mini SSC II in 180 mode Always check out unfamiliar servos before using them with the Mini SSC II in 180 mode Move the servo a few units at a time toward the end of travel and see whether it stalls If it does either use the servo only in 90 mode or restrict position values to the safe range Please understand that servos are designed for 90 motion The 180 mode exploits additional range that is meant as allowance for mechanical and electrical tolerances In other words it cheats a little to allow you to get the most from a given servo There s nothing wrong with a servo that wont do 180 I dentification With no jumper at servo addresses match the numbers printed next to the servo hea
3. Again LOCATE 8 1 PRINT a LOCATE 8 1 INPUT Servo position gt Servo Position Perform some basic error trapping IF Servo gt 7 THEN Servo 7 IF Servo lt 0 THEN Servo 0 IF Position gt 254 THEN Position IF Position lt 0 THEN Position 0 PRINT 1 CHRS Sync byte CHRS S GOTO Again 254 ervo CHRS Position For more Mini SSC program examples plus links to users Mini SSC projects see www seetron com ssc htm s 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com
4. YELLOW RED and BLACK unused Figure 2 Wiring DB9 serial connector to a modular cable for use with SSC Connecting the Mini SSC II continued Figure 2 above shows how to wire an SSC cable for use with the DB9 connector found on PCs and other computers If you prefer not to make your own cable a ready made one is available from Scott Edwards Electronics Inc as part number SSC CBL online www seetron com You may purchase the components used in this cable from J ames Electronics www jameco com or 1 800 831 4242 Figure 3 shows how the cable is assembled DB to modular adapter 7 foot modular cable a Jameco PN 115553 DB9 female Jameco PN 114737 Adapter Setup DB9 YELLOW pin5 GREEN pin 3 RED cut off BLACK cut off Figure 3 Solderless SSC cable equivalent to SSC CBL The DB9 to modular adapter comes disassembled To assemble it push the pin sockets into the numbered holes in the housing as indicated in the drawing above Snap the adapter housing together and plug in the modular cable Note that you can use most any modular cable intended for connecting a phone to the wall jack The only requirement is that the cable be a four wire type with yellow green red and black wires all connected Two wire cables that come with cheap telephones have only the red and black wires and won t work You can check by looking through the transparent phone plug body if you see four wires it s OK
5. for a list or a serial test program such as Serial Sender available free from www seetron com dl shtml Make sure that the program s baud rate matches the Mini SSC II s setting and that the 1 O pin or comm port selected for serial output is the one the Mini SSC II is connected to Programming for the Mini SSC II To command a servo to a new position requires sending three bytes at the appropriate serial rate 2400 or 9600 baud depending on the setting of the B jumper see Configuring the Mini SSC I1 These bytes Byte 1 Byte 2 Byte 3 sync marker 255 servo 0 254 position 0 254 These must be sent as individual byte values not as text representations of numbers as you might type at a keyboard The example programs at the back of this manual show how to convert numbers to byte values In PBASIC you just omit any text formatting functions for the BS1 DEC HEX etc for the BS2 In other BASICs use the CHR function to convert numbers to bytes The Sync LED on the Mini SSC II board can help you debug your serial routines It lights steadily when power is first applied to the board and stays on until the first complete three byte instruction is received Thereafter the LED lights only after a valid sync marker and servo address are received It stays on until a position byte is received then turns off If your program is sending lots of data to the Mini SSC II the LED will appear to light steadily but will ac
6. syne con 255 Mini SSC sync byte pos var byte Byte variable holds position value n96n con 4054 Baudmode 9600 baud BS2 SX change to 40F0 n24n con 418D Baudmode 2400 baud BS2 SX change to 43FD more on next page 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 8 BS2 program example continued again for pos 0 to 254 step 1 Rotate clockwise in l unit steps serout 0 n96n sync svo pos Command the mini SSC next Next position for pos 254 to 0 step 1 Rotate counter clock l unit steps serout 0 n96n sync svo pos Command the mini SSC next Next position goto again Do it again Listing 3 QBASIC Program for PCs Demonstrating the Mini SSC Note This program is written for QBASIC an old but still common MS DOS programming language For programming under Windows 95 or greater with Visual BASIC see www seetron com ssc_anl htm DEFINT A Z Syne byte 255 The line below assumes that the B jumper is installed for 9600 baud operation OPEN coml 9600 N 8 1 CD0 CS0 DS0 OP0 FOR OUTPUT AS 1 CLS PRINT MINI SERIAL SERVO CONTROLLER PRINT PRINT PRINT At the prompt type the servo number 0 to 7 a comma PRINT and a position value 0 to 254 PRINT Press lt CNTL gt lt Break gt to end
7. to the wires to red and to black Do not reverse and even momentarily This can damage the electronics The SSC power input is protected against accidental 9V battery reversal but higher input voltages can defeat this protection Serial Input The Mini SSC II requires only two connections to a computer serial data and signal ground There are two places to make these connections a modular phone jack and two pairs of pins marked S in on the configuration header It doesn t matter which you use pick the connection that is most convenient With single board computers like the BASIC Stamp you will probably use the header pins Connect the Stamp I O pin that your program will use for serial output to S on the Mini SSC II This will be one of pins 0 7 on the Stamp I or pins PO P7 on the BS2 Don t use BS2 pin Sout it s A NN for communicating with your PC during programming In either case ee signal ground connect Stamp Ground Vss toG Note that there are two S pins and two G pins These make a convenient tie point for connecting multiple Mini SSC IIs tothe same serial input See Multiple Mini SSCs s 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 4 DB 9 Female SOLDER SIDE GREEN Serial Z Phone Base not handset Cable 1 5 aoe Coen oo0oo0o0
8. NEVER connect the Mini SSC II tothe phone line 25 pin Serial Ports These are almost extinct but if your computer has one just use a commercial DB25 to DB9 adapter and one of the cables shown above s 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 5 Initial Checkout When the Mini SSC II is first powered up it will turn on the Sync LED and move all servos to the centered position see Theory of Operation Once you have connected servos servo power and Mini SSC power the servos will immediately swing to center If they are already centered they may not move much but you can confirm proper operation by trying to move a servo with your fingers gently The servo will resist your efforts to move it If it doesn t recheck servo and power connections The Green Light At powerup the green Sync LED indicates not only that the Mini SSC II is receiving power but also that its microcontroller is working properly passed startup initialization If the green light comes on but servos don t appear to be responding correctly the problem is most likely with servo connections servo power or serial hookup not with the Mini SSC II Serial Checkout To verify proper serial hookup run one of the demonstration programs a commercial Mini SSC II software package see www seetron com ssc htm
9. at fit the pins on the Mini SSC II board or any 0 025 More than 16 servos With a jumper installed at the Mini SSC II adds 8 to the servo addresses so that servo 0 s address is 8 servo 1 is 9 and servo 7 is 15 If you need to control more than 16 servos you may special order Mini SSC IIs with higher address ranges from the manufacturer For example your third and fourth Mini SSC IIs would have a base address the address corresponding to servo 0 with nol jumper of 16 Part numbers for these special Mini SSC IIs is SSC ASD2 n where n is the base servo number The table bel ow lists the first five part numbers and the range of servo numbers they cover Part Number Servo s no jumper at I Servo s jumper at I SSC ASD2 standard 0 7 8 15 SSC ASD2 16 16 23 24 31 SSC ASD2 32 32 39 40 47 SSC ASD2 48 48 55 56 63 SSC ASD2 64 64 71 72 79 Theory of Operation Pulse proportional servos are designed for use in radio controlled R C cars boats and planes They provide precise control for steering throttle rudder etc using a signal that is easy to transmit and receive The signal consists of pulses ranging from 1 to 2 milliseconds long repeated 60 times a second The servo positions its output shaft in proportion to the width of the seio pulse as shown in Figure 5 centered In radio control applications a servo needs no more than a 90 range of motion since it is usually driving a crank mechanism that can t
10. damages resulting from any breach of warranty or under any legal theory including lost profits downtime goodwill damage to or replacement of equipment or property and any costs or recovering reprogramming or reproducing of data associated with the use of the hardware or software described herein Warranty Scott Edwards Electronics Inc warrants this product against defects in materials and workmanship for a period of 90 days If you discover a defect we will at our option repair replace or refund the purchase price Return the product with a description of the problem We will return your product or its replacement via standard shipping Expedited shipping is available at the customer s expense e Note Physically abusing the module or attempting to repair or modify it voids this warranty Trademarks and Copyrights Mini SSC is a trademark of Scott Edwards Electronics Inc BASIC Stamp is a registered trademark of Parallax Inc All trademarked names referenced herein are the property of their respective holders This manual in its entirety is copyright Scott Edwards Electronics Inc 1999 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 2 Connections and Configuration Jumpers Figure 1 shows the layout of the Mini SSC II circuit board with the locations of connecto
11. ders 0 through 7 With a jumper at the Mini SSC adds 8 to these addresses so that the servo connected to 0 is addressed as 8 1 as 9 and 7 as 15 This allows you to connect two Mini SSC IIs tothe same serial port and address each of the servos individually See Multiple Mini SSCs for information on controlling more Mini SSC IIs froma single serial port B aud With no jumper at B the Mini SSC II receives serial data at 2400 baud with B jumpered the baud rate is 9600 In either case the data should be sent as 8 data bits no parity 1 or more stop bit s abbreviated N81 In addition the data should be inverted just the way it comes from a standard Connecting the Mini SSC II Servos The Mini SSC II connector accepts standard three conductor servo plugs e g F utaba J connectors See figure 1 for the correct way to attach these connectors Servo Power Connect power for the servos 4 8 to 6Vdc to the red and black wires marked SVO on the Mini SSC II board Do not reverse and even momentarily This will damage the servos For a power source use a four pack of alkaline C or D cells For an ac power supply use a regulated linear not switching supply rated for 5Vdc at 1A or more For more specific power supply recommendations see www seetron com ssc_faq htm Mini SSC II Power Connect a 9V battery to the battery snap If you want to use another power source cut off the snap and connect 7 to 15Vdc
12. mm A 1 pino S in pin S Serial signal E Vss S in pin G Ground Plug a servo into Mini SSC output 0 and connect power as described in the manual Run this program The servo will slowly scan back and forth Change for next step values to change servo movement SYMBOL svo 0 Use servo 0 SYMBOL sync 255 Mini SSC sync byte SYMBOL pos b2 Byte variable b2 holds position value again for pos 0 to 254 step 1 Rotate clockwise in l unit steps serout 0 n2400 sync svo pos Command the Mini SSC next pos Next position for pos 254 to 0 step 1 Rotate counter clock l unit steps serout 0 n2400 sync svo pos Command the mini SSC next pos Next position goto again Do it again Listing 2 BASIC Stamp II Program Demonstrating the Mini SSC Program SCAN BS2 BS2 servo control demo This program demonstrates servo control using the MiniSSC It commands servo 0 slowly and smoothly through its full range of travel To run this program install a jumper at B on the Mini SSC board leave all other jumpers off Connect BS2 Mini SSC Purpose a 0 E eo ee i PO S in pin S Serial signal Vss S in pin G Ground Plug a servo into Mini SSC output 0 and connect power as described in the manual Run this program The servo will slowly scan back and forth Try changing the step values in the for next loops to see the effect on servo movement svo con 0 Use servo 0
13. move more than 90 So when you send pulses within the manufacturer specified range of 1 to 2 ms you get a 90 range of motion With no jumper at the R ange header a position value of 0 corresponds to 1 ms pulses 254 to 2 016 ms A 1 unit change in position value produces a 4 microsecond change in pulse width Positioning resolution is 0 36 unit 90 250 Figure 5 Servos are controlled by 1 to 2 ms pulses repeating at 60Hz Most servos have more than 90 of mechanical range though in order to allow adjustment for component variations mounting position etc The Mini SSC II lets you use this extra range With a jumper at R ange a position value of 0 corresponds to 0 5 ms pulse 254 to 2 53 ms A 1 unit changein position value produces a 8 microsecond change in pulse width Positioning resolution is 0 72 unit 180 250 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 e www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 7 Program Examples Listing 1 BASIC Stamp I Program Demonstrating the Mini SSC Program SCAN BAS BS1 servo control demo This program demonstrates servo control using the MiniSSCc It commands servo 0 slowly and smoothly through its full range of travel To run this program leave all configuration jumpers off the Mini SSC board Connect BSI Mini SSC Purpose ES OOO T
14. rs and configuration jumpers Serial Input nfiguration jumper SSC CBL see figs 2 3 Eon suneas en Mpers p Jumper 7 Function off on Description Serial in always never Do not jumper Serial in always never Do not jumper Power for SSC f Vb range 90 180 Range of motion attery snap identification 0 7 8 15 Servo addresses she baud rate 2400 9600 Baud rate Red wire is A EET l0 Servo connection for 5 EA PWM 7 lA power do not Eil Sossar V red reverse notch N GND black Power for Servos 4 8 6Vdc servo asic Gey ay sae eae connector servo connectors servo header 36 0 by 54 mm 1 4 by 2 1 in servo number Q Do not reverse power polarity even momentarily Reversed power will destroy the electronics Do not exceed 10V into SSC 9V input Overvoltage may damage the unit or shorten its life The phone jack is for serial input only Connecting it to the telephone system will damage the unit Figure 1 Layout of the Mini SSC II circuit board Configuring the Mini SSC II The Mini SSC II s default configuration all jumpers removed is 2400 baud servos 0 through 7 range of motion 90 To change a setting install a jumper block across the appropriate pair of header posts as shown in the drawing at right Changes take effect the next time the SSC is powered B Here are more details on the configuration options
15. tually be blinking very rapidly Windows 95 98 NT programming A 32 bit Windows DLL is available free from our web site at www seetron com ssc_an1 htm Documentation includes a complete description of the DLL plus program examples for Microsoft Visual BASIC 6 and Borland Delphi 5 The DLL may be used with any Windows programming environment that supports DLLs Multiple Mini SSCs To control two Mini SSC IIs connect them in parallel to the same serial line see wiring suggestions on the next page Set both units for the same baud rate Install a jumper at the configuration header of one leave this header open on the other Address the servos as follows Jumper at 1 Servo Numbers no 0 7 yes 8 15 1939 S Frontage Road Suite F Sierra Vista AZ 85635 USA Scott Edwards Electronics Inc ph 520 459 4802 fax 520 459 0623 e www seetron com User s Manual SSC ASD2 v2 1 07 00 pg 6 Multiple Mini SSCs continued Wiring suggestions for multiple Mini SSC IIs Once you have one Mini SSC II connected toa computer connecting additional units is easy J ust wire the S and G pins of the first Mini SSC II to the S and G pins of the second Do the same for the second and third third and fourth and so on Since there are two S pins and two G pins on each Mini SSC II this is simple To make these connections without soldering use Connectamundos jumper wires CN X 010 from Scott Edwards Electronics Inc These have sockets th
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