nrf9160 interrupts {

[ephraim]

Dear Sir.

I have a question regarding the nRF9160 Interrupt procedure.

I have 2 interrupts on my nRF9160 custom board.

The 1st interrupt is an external interrupt every 2mSec.

 Set up for the external interrupt :

 

void AFE4900_Interrupt_Config(void)
{
    gpio_pin_configure(dev_io, GPIO_INT_PIN, GPIO_DIR_IN | GPIO_INT | GPIO_PUD_PULL_UP | GPIO_INT_EDGE);
    gpio_init_callback(&gpio_cb, AFE4900_Interrupt, BIT(GPIO_INT_PIN));
    gpio_add_callback(dev_io, &gpio_cb);
    gpio_pin_enable_callback(dev_io, GPIO_INT_PIN);
}

 

 The 2nd interrupt is 1 hz interrupt (timer interrupt configured by the CPU) :

  

  k_timer_init(&my_timer, my_expiry_function, NULL);

        k_timer_start(&my_timer, K_SECONDS(TIEMR_INTERVAL_SEC),K_SECONDS(TIEMR_INTERVAL_SEC));

 

What happens is that the 1hz timer has a high priority then the external interrupt , 

I measure in the scope and see that external interrupt is shifted by time when the 1hz interrupt occurs.

How can I set the external interrupt to have higher priority than the timer interrupt ?.

[Håkon Alseth]

Hi,

 

 

k_timer_init(&my_timer, my_expiry_function, NULL);

 This will run in interrupt priority, which is inherited from the kernel timer instance RTC1, which is hardcoded with this priority:

https://github.com/nrfconnect/sdk-zephyr/blob/master/drivers/timer/nrf_rtc_timer.c#L102

 

I wouldn't recommend changing this.

 

How can I set the external interrupt to have higher priority than the timer interrupt ?.

GPIOTE needs to have a higher priority than RTC1, which has '1', so you'll need GPIOTE prio to '0'.

This can be done by creating a $board_name.overlay file (nrf9160_pca10090ns.overlay if using ncs tag v1.2.0, nrf9160dk_nrf9160ns.overlay on current master) holding your configuration:

&gpiote {
    status = "okay";
    interrupts = <49 0>;
};

 

I tested the above with the zephyr/samples/basic/button, where I added this to the button callback:

void button_pressed(struct device *gpiob, struct gpio_callback *cb,
		    u32_t pins)
{
	printk("Button pressed at %" PRIu32 "\n", k_cycle_get_32());
	printk("GPIOTE ISR Prio: %d\n", NVIC_GetPriority(GPIOTE1_IRQn));
	printk("RTC1 ISR Prio: %d\n", NVIC_GetPriority(RTC1_IRQn));
}

 

And it now prints this:

Button pressed at 26472
GPIOTE ISR Prio: 1
RTC1 ISR Prio: 2

 

A side note: In DTS, the number is offset by '1' compared to what is read out from the NVIC (NVIC_GetPriority(...)). 0 in DTS -> 1 when you read NVIC directly.

 

Could you try this and see if it works better?

You can also consider to use a system workqueue when handling larger non-timing critical logic in interrupt handlers.

 

Kind regards,

Håkon

[ephraim]

Hi.

It works , Many thanks

One more question before I close this post .

Where can I find the document of how to set the priority GPTIOE 49,0 ?.

[Håkon Alseth]

Hi,

 

ephraim said:

Where can I find the document of how to set the priority GPTIOE 49,0 ?.

The description in dts is available, but not the usage of the magic number corresponding to the NVIC IRQn number:

https://github.com/zephyrproject-rtos/zephyr/blob/master/dts/bindings/interrupt-controller/arm%2Cv8m-nvic.yaml

 

I have opened up a discussion with the developers on how this can be made easier. This vector-number corresponds to the GPIOTE_IRQn define. For nRF9160, in non-secure mode, it is this one:

https://github.com/zephyrproject-rtos/hal_nordic/blob/master/nrfx/mdk/nrf9160.h#L113

 

Note that this number will be different if you run on nRF52832, 840, etc. Then you have to manually check the "IRQn_Type" number for that specific device.

I'll be sure to bring this tedious configuration up with the developers, and see if we can get a better solution in the future.

 

Kind regards,

Håkon