Interrupt priority

[Artem Zemlyanukhin]

Hi,

While the softdevice is active (nRF51822) available interrupt priorities are:

typedef enum { NRF_APP_PRIORITY_HIGH = 1, NRF_APP_PRIORITY_LOW = 3 } nrf_app_irq_priority_t;

1. Can I use interrupt priority = 2?
2. SVC priority is 2, is it true? So I could't use Softdevice api-functions in interrupt handlers with NRF_APP_PRIORITY_HIGH priority?
3. What does define "#define NRF_APP_PRIORITY_THREAD 4" in app_util.h mean?

Artem Z. Best Regards

[Audun]

Hi Artem,

to answer your questions

• 1. Can I use interrupt priority = 2? No, not while the SoftDevice is active. If you try to set this priority level using sd_nvic_SetPriority() you will get an error.
• 2. SVC priority is 2, is it true? So I could't use Softdevice api-functions in interrupt handlers with NRF_APP_PRIORITY_HIGH priority? Correct. You would need to pass execution to a lower priority level, for example by using a software interrupt (SWIRQ) with NRF_APP_PRIORITY_LOW.
• 3. What does define "#define NRF_APP_PRIORITY_THREAD 4" in app_util.h mean? It's used in "current_int_priority_get()" to indicate if the CPU is running in thread mode (main context), as opposed to running in interrupt mode with interrupt priority 0-3.

[Artem Zemlyanukhin]

Hi Audun,

Thanks for reply.

One more question. Consider Write Request without Authorization. After receive "Write Request" and send "Write Response" Stack generate event BLE_GATTS_EVT_WRITE. As I understand, at first Stack handles Radio_IRQ with priority = 0 (max configuring priority for cortex m0) and then via software interrupt handle SWI2_IRQ with priority = 3 (where stack calls ble_evt_dispatch()). My question is in what handler (SWI2, Radio or somewhere else) really attribute will be written in GATT table?

I asked this question because I am interested in what will happen if write request will be received during processing sd_ble_gatts_value_set()? For example: my service has attribute "Counter". Application is incrementing it's value via sd_ble_gatts_value_set(). And during sd_ble_gatts_value_set() stack receives "ATT Write request" to reset attribute "Counter" (assigns it to 0). How stack will resolve this situation?

I suppose at first stack set this value in sd_ble_gatts_value_set(), then after SVC handler return, Stack will assign new value for attribute in SWI2 handler (this is the value received via write request).