XRP Servo 1 vs 2 differences in behavior

In our shop, we had some backup DIY XRP kits so two mentors tested using those boards, and the behavior was different between the two new boards.

  • Both boards
    • plugged into only micro-USB power (no DC jack power)
    • no other motors/servos connected
    • running microPython via xrpcode.
    • running blockly code that sets servos to “100” which should be 1500us or stationary
    • ran the digital versions of the servos w/o issue
  • Board A
    • Servo 1 worked as expected w/ the analog servo (no movement, but upon initial plug in, the servo moved a little)
    • Servo 2 ran continuously
  • Board B
    • Servo 1 and 2 both ran continuously w/ the analog servo

I’ll see if I can find a small capacitor in my stash of toys. If it doesn’t help, I’ll send you both boards and 1 of each servo I am testing.

That’s so weird. Would love to get to the bottom of this!

Hi @SparkFro, we experienced another issue last night with regards to driving DC motors using Motor Ports 2 and 3. It seems that if there’s any sort of load/resistance on the DC motor, the Pico W board reboots. We tried both fresh rechargeable and alkaline batteries. Interestingly enough, if the micro-USB connector is plugged in, the Pico W does NOT reboot when driving the DC motors.

I’ll get the boards and servos ready to send out sometime next week. I’ll include some DC motors, too.

Are you using the motors that come with the kit, or different motors? If different, could you please link to the product page or spec sheet for the motors?

These are simple hobby DC motors that don’t have encoders, so just using the M+/M- pins: Gikfun 1.5V-6V Type 130 Miniature DC Motors for Arduino Hobby Projects DIY (Case Pack of 6) EK1450 - Amazon.com

Sorry for delay, mad rush to get things done this week before the holiday break! Also FYI, I’ll be out until January.

Cant find current consumption specs on those motors, so it’s possible they require a large surge in current to start moving, enough to cause a brownout. Can’t say anything more without testing the motors myself, but you could try ramping up the motor speed to minimize surge current.