PaPiRus Zero or Inky pHAT stacked with Envrio pHat



Am I correct in thinking that neither the Micro Dot pHat or PaPiRus Zero could be stacked with an Enviro pHat on a Pi Zero W as they both use the BCM2 and BCM3 pins that Enviro also uses?

But correct in thinking that the Inky pHat could be stacked on top of an Enviro pHat as it does not share any pins with it?



It’s possibly not communicated well on Pinout, but BCM2 and BCM3 are used for i2c on all of the pHATs you list. This means it’s used as a bus that communicates with multiple devices, including devices on multiple pHATs, as long as their i2c addresses don’t conflict.

You’ll find that both Micro Dot pHAT and Papirus Zero will work fine with Enviro pHAT since, fortunately, there are no address conflicts!


Can you enlighten me, how do we find if there would be conflicts ?


If it’s documented on pinout you look for this bit:

Communication over I2C
0x62: IS31FL3730
0x63: IS31FL3730
0x61: IS31FL3730

Which lists all the addresses and devices that board uses.

If any of those addresses match up with one from another board, that’s a conflict.

You can put each HAT/pHAT on your Pi individually and run sudo i2cdetect -y 1 to see a list of detective devices otherwise. You may need to use sudo i2cdetetc -q 1 in some cases where devices are write-only.