Why does setting NRF_PPI->TASKS_CHG[n].DIS = 1 cause a hardfault?

[David Woosley]

The statements NRF_PPI->TASKS_CHG[n].DIS = 1, and sd_ppi_group_task_disable(n) cause a hardfault when NRF_UICR->CLENR0 is set to the start of the application code, but do not cause a hardfault when NRF_UICR->CLENR0 is cleared to 0xFFFFFFFF. I have tried channels 0, 1, and 2. This call occurs before the main loop is exited, but well after softdevice is enabled. I have checked and found value of NRF_PPI->TASKS_CHG[n].DIS is already zero. Can PPI groups be used while the softdevice is protected? Thanks in advance for any insights.

[RK]

Which softdevice version? The earlier ones protected the PPI peripheral, the recent ones do not.

[David Woosley]

s310_nrf51422_2.0.1

[Petter Myhre]

I just tested this with S310 2.0.1.

err_code = sd_ppi_group_task_disable(0);
APP_ERROR_CHECK(err_code);

returns 0x00000000 = NRF_SUCCESS, and there is no hard fault.

err_code = sd_ppi_group_task_disable(2);
APP_ERROR_CHECK(err_code);

returns 0x00002009 = NRF_ERROR_SOC_PPI_INVALID_GROUP, and there is no hard fault.

This is expected behavior according to Section 12.6 in the S310 SoftDevice spec.

[David Woosley]

Thanks for looking into this. I'll have to dig deeper.