GPIO-2 and GPIO-3 are for I
2
C communication between Raspberry Pi and the MCU (ATtiny841). I
2
C
devices are identified by I
2
C address, and they can share the I
2
C pins as long as they have different
I
2
C addresses.
15.4 Is Witty Pi 4 Compatible with “Other Hardware”?
We have got a lot of emails asking a question like this, with the “Other Hardware” replaced by
different kinds of hardware.
Please understand that we might not have the hardware you refer, and even if we have, it is difficult
for us to make tests on all those hardware with Witty Pi 4. Fortunately, it is not that difficult to figure
out the answer by yourself. Basically, you just need to consider the I
2
C address and GPIO pins used
by the “Other Hardware”.
If the “Other Hardware” also uses 0x08 I
2
C address, you will need to change the I
2
C address used by
Witty Pi’s micro controller, and change the software accordingly (details here).
If the “Other Hardware” doesn’t use any GPIO pin that used by Witty Pi, then it should be compatible
with Witty Pi.
If you have no idea which I
2
C address (if applicable) or GPIO pins are used by the “Other Hardware”,
please contact its developer, as they certainly know their hardware and can provide you accurate
information about it.
15.5 Witty Pi 4 does not boot?
Some customers meet the situation that Witty Pi 4 only boot Raspberry Pi for a few seconds, and
then shutdown Raspberry Pi or cut the power directly.
Remarks: you may need to disconnect Witty Pi 4 from your Raspberry Pi, and power on Raspberry
Pi only for troubleshooting.
Before making further troubleshooting, please first check these interfaces are properly configured:
I2C interface should be enabled
Serial Port should be enabled
1-Wire interface should be disabled if you don’t need it, or you need to assign a GPIO pin
other than GPIO-4 to it.
If your Raspbian (Raspberry Pi OS) has GUI installed, you can review/configure these interfaces via
Raspberry Pi Configuration:
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