3pi on 3.3V?

we could name it 3.3pi …
Any reason not changing the Vcc to 3.3 V?
328p would run on 16 MHz
any other reason to stay with 5V?
the point is …all the wifi and bluetooth modules I have found run on 3.3V
And I guess the 4 MHz clock difference would not kill the 3pi usability.
Could you give me a hint which IC to replace?


According to the ATmega328P datasheet, it is out of spec run above 10 MHz when Vcc is below 4.5 V, and 3.3 V is below the minimum logic supply voltage of the 3pi’s TB6612FNG motor driver. Also, the many parts of the Pololu AVR library code would have to change somewhat substantially if you change the CPU clock frequency.

I think the much easier solution is to just use a separate 3.3 V regulator to power your 3.3 V devices (e.g. bluetooth modules) and use level shifters when interfacing them with the 3pi. You can see how this is done on the m3pi, which lets you use a 3.3 V mbed module to control a 3pi robot.

- Ben

Hi Ben,
The mbed extension kit might be the best solution … what I fear is the mechanical slow down.
The h-bridge chip works at 3v typical operation according to the spec.
The CPU frequency is linear to vcc, should work at least til 12 MHz.
The libs …might be an issue. Would be a good idea to make it frequency independent.
But yes …a lot of work and risk compared to a known working solution with mbed.
I will check where to get one.

My apologies; you’re right, the TB6612FNG logic will work at 3.3 V.

- Ben