LATCH Register does not correctly indicate GPIO after wakeup from SYSTEM OFF

[Stefan Schmidt]

Hello Nordic-Team,

 I am using the SENSING mechanism on GPIOs to wake up a firmware from SYSTEM OFF. Two GPIOs are used for this and it is crucial for the firmware to detect which GPIO caused the wakeup.

On a nRF54L05 (nRF54L15 used as nRF54L05) I am able to readout the GPIO that caused the wakeup, on a nRF54LS05B the corresponding bits for both GPIOs are set even if only one button was pressed, so that I cannot detect the wakeup reason.

Please find attached a test firmware which I used with nRF Connect SDK v3.3.0 on a nRF54L15-DK and a nRF54LS05-DK.

Button0 and Button1 are used to wakeup the firmware.

Best regards

sensing_test_app.zip

[Stefan Schmidt]

Debug log on the nRF54L15DK:
*** Booting nRF Connect SDK v3.3.0-ba167d9f3db4 ***
*** Using Zephyr OS v4.3.99-fd9204a02d52 ***
check_reset_reason: reason = 0x00000100 OFF
latch after wakeup: 0x00000200
latch after clear:  0x00000000
*** Booting nRF Connect SDK v3.3.0-ba167d9f3db4 ***
*** Using Zephyr OS v4.3.99-fd9204a02d52 ***
check_reset_reason: reason = 0x00000100 OFF
latch after wakeup: 0x00002000
latch after clear:  0x00000000

Debug log on the nRF54LS05DK:
*** Using Zephyr OS v4.3.99-fd9204a02d52 ***
check_reset_reason: reason = 0x00000100 OFF
latch after wakeup: 0x00002200
latch after clear:  0x00000000
enter SYSTEM OFF*** Booting nRF Connect SDK v3.3.0-ba167d9f3db4 ***
*** Using Zephyr OS v4.3.99-fd9204a02d52 ***
check_reset_reason: reason = 0x00000100 OFF
latch after wakeup: 0x00002200
latch after clear:  0x00000000