On the 54l15 chip, in the NCSv3.0 peripheral_uart example routine, when using timer20 to set a 1-second timer, the actual time is only 995ms.

[yuanFang]

peripheral_uart_1_timer20.zip

#include <nrfx_timer.h>

CONFIG_NRFX_TIMER20=y

#define TIMER_INST_IDX 20
const nrfx_timer_t timer_instance = NRFX_TIMER_INSTANCE(TIMER_INST_IDX);

void timer_event_handler(nrf_timer_event_t event_type, void *p_context)
{
    gpio_pin_set_raw(gpin[1].port, gpin[1].pin, 1);
    gpio_pin_set_raw(gpin[1].port, gpin[1].pin, 0);
    // nrfx_timer_clear(&timer_instance);
    
}

static void configure_timer(void)
{
    IRQ_CONNECT(NRFX_IRQ_NUMBER_GET(NRF_TIMER_INST_GET(TIMER_INST_IDX)), IRQ_PRIO_LOWEST,
                NRFX_TIMER_INST_HANDLER_GET(TIMER_INST_IDX), 0, 0);
    nrfx_err_t err;

    nrfx_timer_config_t timer_config = {
		.frequency = NRFX_MHZ_TO_HZ(8),
		.mode      = NRF_TIMER_MODE_TIMER,
		.bit_width = NRF_TIMER_BIT_WIDTH_32,
        .interrupt_priority = NRFX_TIMER_DEFAULT_CONFIG_IRQ_PRIORITY,
        .p_context = NULL,
	};
    err = nrfx_timer_init(&timer_instance, &timer_config, timer_event_handler);
    if (err != NRFX_SUCCESS) {
        LOG_ERR("nrfx_timer_init error: %08x", err);
        return;
    }

    nrfx_timer_clear(&timer_instance);

    nrfx_timer_extended_compare(&timer_instance, NRF_TIMER_CC_CHANNEL0, nrfx_timer_us_to_ticks(&timer_instance, 1000000),
        NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);

}

The attachment "peripheral_uart_1_timer20.zip" is the project engineering file. Actual tests show that timer20 is not as accurate as Ktimer.

Another strange thing is that even though I added &timer20 { status = "disable"; }; in the "overlay" file, timer20 can still run normally.

We urgently need your reply. Our PCB boards have arrived, and this timer is the most important function for our project.

Thank you very much.

[Håkon Alseth]

Hi,

 

The default behavior is that the HFCLK runs from the HFRC. To force the HFXO, you can start the clock, like shown in the direct_test_mode example:

https://github.com/nrfconnect/sdk-nrf/blob/v2.9-branch/samples/peripheral/radio_test/src/main.c#L18

 

Could you try this and check the accuracy afterwards?

 

Kind regards,

Håkon

[yuanFang]

Thank you very much. After adding clock_init(), the timer has become accurate.

Another strange thing is that even though I added &timer20 { status = "disable"; }; in the "overlay" file, timer20 can still run normally.

[Håkon Alseth]

Hi,

 

Glad to hear that it now works as expected.

yuanFang said:

Another strange thing is that even though I added &timer20 { status = "disable"; }; in the "overlay" file, timer20 can still run normally.

Yes, this is overriding and selecting the low level nrfx_timer driver, instead of using zephyr's "timer" subsys.

 

Kind regards,

Håkon