Sunday, 18 November 2007

Problems with P0.7 of PCF8575

I recently discovered I have problems when controlling the PCF8575 (16-bit I2C controlled IO expander) in such a way, that P0.7 is put as input (so, P0.7 is high).
Whenever P0.7 is put high, all other pins (P0.0 - P0.6 as well as P1.0 - P1.7) are becoming inputs too, whatever their previous state (input or output).
Also, the PCF8575 does not detect any input changes any more...

I still have no clue at all as to why this IO expander is behaving so strange.

The moment I switch P0.7 as output, all my other pins behave correct again (as input as well as output).

Still looking for a possible cause...

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