Microcontroller suggestion?

Hi all, here's my project: a Wall-E toy. I got it from ebay and gutted it, with the intention to replace all the internal mechanisms with 3D printed parts, servos, motors, and a microcontroller. I did some prototyping and have mostly figured out the interface between the microcontroller and the mechanical parts.

  • A servo to rotate the head
  • A servo to control eye movements
  • Two LEDs for the eyes
  • Two servos to raise and lower the arms
  • An IR receiver if I want to interface it with a remote control
  • Two DC motors for treads on both sides
  • A speaker to make sounds
  • A push button

I have a few Pro Micros in the house and that's what I've been using for prototyping. But I soon realized that I'm running out of pins, especially PWM pins. The two DC motors use 4; the two eyes use two (I want to be able to create a breathing pattern, hence PWM); That has already exhausted the 6 PWM pins on Pro Micro, without the speaker. I glanced at a PCM Library and it looks like playing audio will occupy 4 PWM pins. I'm aware of software PWM solutions. But I'd rather keep it simple if possible.

So, at this point, my conclusion is, anything based on ATMegaU4 is not going to cut it. I'll need to look for something else. Since it'll be powered by 4 AA batteries, I want to keep it simple and low power. Although admittedly, the motors and servos will probably be the main power drain.

I'm new to Arduino (not new to coding, which I've been doing for a living for 2 decades). So I'd like to pick people's brain on finding a good solution here. Any suggestions will be appreciated. Thanks!

The Arduino Mega might have enough pins. Make a careful inventory of exactly how many pins and functions (like PWM, servo, audio) are required by your application and compare.

Keep in mind that some libraries (servo, IR, PCM audio) might conflict over timer usage.

Add more PWM pins with pca9685?

1 Like

And you can get it on a breakout board:

Huh, that looks super promising! It sounds like it can easily handle 2 motors, 4 servos, and 2 LEDs on its own without tying up the timers on the microcontroller. I'll get one and do some prototyping.

Thanks!

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.