Servo32 behaving unexpectedly

Jay Kickliter

I have two servos connected to a PPDB. They're powered from VDD.

The strange thing is that only the first servo I set actually gets activated. Unplugging them and hooking up the signal lines to LEDs confirms that only the first servo set is receivng a signal, any after that are inactive. If I comment out the first servo.set(), then the next servo does get a signal. I've tried all the normal swapping and ohming troubleshooting, but I can't find anything.

The servo32 object seems pretty straight forward, but here's my code:

CON
    _clkmode  = xtal1 + pll16x
    _xinfreq  = 5_000_000                                'Note Clock Speed for your setup!!
    CR        = $0D
    LF        = $0A
    PAN_SERVO = 12
    TILT_SERVO = 14

VAR
   word       servoPanSetPoint, servoTiltSetPoint
   byte       rxByte, packetBuffer[noparse][[/noparse]20], validPacket

OBJ
  servo       : "Servo32v3"
  serial      : "FullDuplexSerial"

PUB main | i, temp
  serial.start(31, 30, 0, 9600)
  servo.start
  servoPanSetPoint := 1100
  servoTiltSetPoint := 1900
  validPacket := 0
  servo.set(PAN_SERVO, servoPanSetPoint)
  servo.set(TILT_SERVO, servoTiltSetPoint)
  repeat
    if validPacket
      serial.str(string("Setting pan to: "))
      serial.dec(servoPanSetPoint)
      serial.str(string(" and tilt to: "))
      serial.dec(servoTiltSetPoint)
      serial.tx(CR)
      servo.set(PAN_SERVO, servoPanSetPoint)
      servo.set(TILT_SERVO, servoTiltSetPoint)
    i := 0
    temp := 0
    repeat until serial.rx == "@"
    repeat until (rxByte := serial.rx) == ","
      temp := temp * 10 + (rxByte - "0")
    servoPanSetPoint := 1000 #> temp <# 2000
    temp := 0
    repeat until (rxByte := serial.rx) == 13 or rxByte == 10
      temp := temp * 10 + (rxByte - "0")
    servoTiltSetPoint := 1000 #> temp <# 2000
    validPacket := 1

Anybody see anything?

Leon

Noise from the motors might be causing a problem.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Beau Schwabe

Jay Kickliter,

To initialize the servo32 object, you need to initialize "servo.set" before you initialize "servo.start"...· This is a safety feature that presets the servo position to a known state, and tells the servo object which pins will be used for the servo(s).

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.