So I’m looking at installing a Raspberry Pi Zero W on my Duet 2 Maestro. I’d like to be able to connect an unused GPIO from the Duet 2 Maestro directly to the Raspberry Pi Zero W GPIO. I know the older Duet boards were all 3.3V, and I thought I read somewhere the Duet Maestro pins were also 3.3V but also tolerated higher voltages on certain pins. Is it as simple as GPIO to GPIO?
I’m looking at having the Raspberry Pi Zero W take a picture with its camera when a GPIO pin goes high, and then have some sort of done GPIO pin back to the Duet Maestro. I know this is do-able over http or telnet, but I want more of a contained solution that doesn’t rely on WiFi or Ethernet working.
From what I’ve seen the Raspberry Pi pins are 3.3V
Two 5V pins and two 3V3 pins are present on the board, as well as a number of ground pins (0V), which are unconfigurable. The remaining pins are all general purpose 3V3 pins, meaning outputs are set to 3V3 and inputs are 3V3-tolerant.
A GPIO pin designated as an output pin can be set to high (3V3) or low (0V).
A GPIO pin designated as an input pin can be read as high (3V3) or low (0V). This is made easier with the use of internal pull-up or pull-down resistors. Pins GPIO2 and GPIO3 have fixed pull-up resistors, but for other pins this can be configured in software.
But is it really that simple and straightforward or should I be putting some sort of optocoupler circuit in between?