0

I have a 2-motor robot project that uses a MP6050 for relative heading (yaw) measurements, and I'm having problems with the I2C bus when the motors are running. I have done most of the things suggested here and elsewhere; 2.2K pullups vs default, shortest possible (3cm) I2C wires, MPU6050 as far away from the motor drivers as possible, reduced I2C clock speed to 100KHz, etc, etc (for additional details, see my blog post on the subject).

So, my question is, why is the I2C bus so sensitive to RFI/EMI, especially with 2.2K pullups to +5V? Looking at the levels with my O'scope shows a 0-4.6V swing, so it's hard to believe that EMI-induced currents could be high enough across 2.2K to pull the 'high' level low enough to be considered a '0', so something else must be going on. Maybe the EMI is getting into the MPU6050 output driver circuit, causing it to turn off? If so, maybe capacitive bypasses on the I2C lines would help. Any ideas? Are other IMU modules less susceptible to motor driver EMI?

TIA,

Frank

  • Is it an original arduino? Have you considered ESP8266/32 as an alternative? These have shielded chips. – user2497 Aug 5 at 16:22
  • I had not considered this at all. I ordered a development board from Adafruit and will give it a try ;-) – user3765883 Aug 6 at 20:07
1

Put a ground plate between your data lines and the power+signal lines used to drive the motor. A GPS ground plate is fine, see link below. You can just cut a piece of metal sheet to fit, or even use folded metal foil connected to ground. Motors are just noisy, and I2C is sensitive. Even updating a I2C LCD can cause noise. I like to use shielded wire (like for headphone- or HDMI cable) if my data lines are more than an inch long. You can shield lines with metal foil and heatshrink, but that’s a mess.

Use an opto-isolator to turn on your motors if a ground plate is not enough. If they only drive in one direction, add a catch diode and a 330pF cap to trim the noise. But they are probably most noisy when running. Good luck with that.

https://www.imnasa.com/en/ground-plate-200x64x12mm-for-gps-etc.html

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.