Well… things aren’t looking great at this point.

I thought I had everything figured out. Raspberry Pi Zero was going to talk over I2C and a level shifter with two Arduino Pro Micros – one for sensors and one for motors.

Rangefinder and LED/phototransistor pairs were working great and reporting nicely back to the Pi over I2C.

I wasn’t worried about the motors because a couple of days ago I had the drive motors working when sending commands using the USB serial on the Arduino (that’s what I was doing in the video from the other day).

But alas, the USB serial port uses timers differently than I2C on the Arduino, and the servos and I2C are arguing over the same 16-bit timer hardware in the 32U4. There is one other 16-bit timer on the chip (Timer3) but when I tried using it instead of Timer1 for the servos it doesn’t have the same kind of access to the pins that Timer1 has.

I think, anyway. The best I could get out of the servos was an occasional irregular “putt”. And now it’s getting late and I’ve spent way too much time staring at datasheets. Oh, and of course when I went to the Arduino forums I was greeted with this today:

Don’t get me wrong – it’s great they’re doing maintenance. I just wish they weren’t doing it NOW.

I know there’s a solution, but my old worn-out brain can’t think of it right now. I guess I could run the sensors over I2C and the motors over UART, but I was hoping for a cleaner, less confusing setup. A different microcontroller? ESP32? Pico? Ehurrrghhh.

At any rate, I need to get to bed. Lots of stuff I’ve been putting off that I should really do tomorrow before I get back to work on this particular project.


  1. Do you want to try the GERT board? I wonder if they would have pulled timers and stuff onto that board instead of having the pi do it alone. You can have it if you want it.

    1. Hmm… I’ve never tried one of those – heard a lot about them a few years ago but not much since. I may have to look into that!

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