11.3 Peripheral Signal Multiplexing on I/O Lines

Multiple PIO Controllers multiplex the I/O lines of the peripheral set.

The section Pinouts defines how the I/O lines are multiplexed on the different PIO Controllers. Several I/O sets are available for each peripheral. However, selecting I/Os from different I/O sets for one peripheral is prohibited.

The column “Reset State” shows whether the PIO line resets in I/O mode or in Peripheral mode. If I/O is shown, the PIO line resets in input with the pull-up enabled, so that the device is maintained in a static state as soon as the reset is released. As a result, the bit corresponding to the PIO line in register PIO_CFGR (PIO Configuration Register) resets low.

If a signal name is shown in the “Reset State” column, the PIO line is assigned to this function and the corresponding bit in PIO_CFGR resets high. That is the case for pins controlling memories, in particular address lines, which require the pin to be driven as soon as the reset is released.

The PIO state can be retained when the system enters Backup mode.