I was under the impression that the first version used PCF8574 for main board and a separate PCF8574 for the expansion board. I had not seen that you used the PCF8575 expansion boards. So you are saying that if I have a board set as 0x24 it assumes its a PCF8575 rather than a PCF8574 and so it thinks that there are 16 stations per board? If that is the case, where would I modify the code to only send 1 byte rather than 2? I am assuming it is somewhere close to here?
I do have some PCA9555 on the way, but don’t know when they will get here. Plus at this point, its almost a challenge to get this working.