2.4.6.2 External Interrupt Line Programming

The steps to set up or change the external interrupt line x configuration are the following:

1. Clear SCFGxR.EN to disable the EIC interrupt source.
2. Perform any external setup that might be required at the source peripheral and wait until the peripheral source output is stabilized.
3. If the glitch filter is enabled on the interrupt line, wait until the Ready flag RDYx is set in the Glitch Filter Configuration Status register (EIC_GFCS).
4. Write the required interrupt line configuration fields among GFSEL, GFEN, POL, LVL into EIC_SCFGxR.
5. If the glitch filter is enabled on the interrupt line, wait until EIC_GFCS.RDYx is set.
6. Set EIC_SCFGxR.EN if the source is not yet enabled and, if required for safety, freeze the interrupt line x configuration by setting EIC_SCFGxR.FRZ.

Example:

If the user desires to stop or minimize the circuit activity after a voltage or frequency failure detection on a rising edge of an EIC interrupt source, the polarity can be changed with a single write to EIC_SCFGxR.POL to detect a falling edge of the same source. Detection of the falling edge source indicates the recovery of a normal condition. In this case, the steps described previously can be ignored.