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51
The I/O
expander
is a Philips PCA9554D at I
2
C address 0x20 / 0x21. The pins are
allocated as shown:
Pin
Signal
1
IO_0
IO_1
3
IO_2
4
IO_3
5
IO_4
6
IO_5
7
IO_6
8
IO_7
9
GND
