NRF9160-SICA-R7 datasheet(19/400 Pages) NORDIC

19 / 400 page

Product overview

3.3.9.1 Interrupt clearing and disabling

Interrupts should always be cleared by writing '0' to the corresponding EVENT register.

Until cleared, interrupts will immediately be re-triggered and cause software interrupt service routines to

be executed repeatedly.

Because the clearing of the EVENT register may take a number of CPU clock cycles, the program should

perform a read from the EVENT register that has been cleared before exiting the interrupt service routine.

This will ensure that the EVENT clearing has taken place before the interrupt service routine is exited. Care

should be taken to ensure that the compiler does not remove the read operation as an optimization.

Similarly, when disabling an interrupt inside an interrupt service routine, the program should perform

a read from the INTEN or INTENCLR registers to ensure that the interrupt is disabled before exiting the

interrupt service routine.

3.3.10 Secure/non-secure peripherals

For some peripherals, the security configuration can change from secure to non-secure, or vice versa. Care

must be taken when changing the security configuration of a peripheral, to prevent security information

leakage and ensure correct operation.

The following sequence should be followed, where applicable, when configuring and changing the security

settings of a peripheral in the SPU — System protection unit on page 259:

1. Stop peripheral operation

2. Disable the peripheral

3. Remove pin connections

4. Disable DPPI connections

5. Clear sensitive registers (e.g. writing back default values)

6. Change peripheral security setting in the SPU — System protection unit on page 259

7. Re-enable the peripheral

Note: Changing security settings on a peripheral during runtime is not advisable.

4418_1315 v2.0

NRF9160-SICA-R7 Datasheet(PDF) 19 Page - Nordic Semiconductor