The r/w byte was never set, resulting in writing zeros into the register instead of actually reading from it.
See the figure from here.
TGpioLinuxPin
When writing to a file via TGpioLinuxPin.WriteToFile failed, the created exception would never actually get raised and the whole operations silently fails.
Two things I stumbled accross:
MCP23S17
The
r/wbyte was never set, resulting in writing zeros into the register instead of actually reading from it. See the figure from here.TGpioLinuxPin
When writing to a file via
TGpioLinuxPin.WriteToFilefailed, the created exception would never actually get raised and the whole operations silently fails.