No preemption in application

RE: No preemption in application

Clonimmus74 — Mon, 30 Jul 2018 11:53:47 GMT

I was mistaken, I moved the function from main to SWI, and there's no preemption.

I changed in ble_stack_init the line to force priority = 2:

NRF_SDH_BLE_OBSERVER(m_ble_observer, 2, ble_evt_handler, NULL);

and I set SWI:

nrf_drv_swi_alloc(&ble_uart_swi, ble_tx_swi_event_handler, APP_IRQ_PRIORITY_LOWEST);

The SWI waits in a loop for a flag set in ble_evt_handler, but it never reaches it. the SWI executes ble_nus_data_send, then I expect the event BLE_GATTS_EVT_HVN_TX_COMPLETE to be triggered, but the program never reaches it since there's no preemption.

If I move the function from SWI (and disable SWI) to main all functions properly.

RE: No preemption in application

Clonimmus74 — Sun, 29 Jul 2018 07:09:20 GMT

Thanks.

Actually, from what I've seen, they don't have the same priority,and as I said I tried forcing different priorities.

I found the problem though, f_ble_tx_complete was initialized with 0 instead of 1, so the first transmission didn't occur. Regardless I moved the UART part to main.

RE: No preemption in application

Håkon Alseth — Fri, 27 Jul 2018 12:37:02 GMT

Hi,

Both these handlers are executed in the NVIC interrupt priority 7, which is why your while-loop will never exit. I'd recommend that you schedule the ble_nus_data_send logic to main context instead.

The define BLE_NUS_BLE_OBSERVER_PRIO will set the priority on which order each hook/callback will be called when polling the event from the softdevice_handler, but they all are still executed in handler context.

Best regards,

Håkon