NRF52840 when using Timer and BLE services I found a problem

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Thu, 07 Jan 2021 12:49:24 GMT

and then I create a timer in the SDK's example ble_template with the same period. when the ble connected, the timer will control the LED toggle in 300HZ. I also found that the period of timer is not accurate and still has error occasionally, So that's why I doubt the BLE will affect the timer

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Thu, 07 Jan 2021 12:42:15 GMT

Yes I didn't start or stop the timer anywhere else, and i build a project use timer and saadc only without ble, the problem was gone so I wonder how often the ble will affect the timer. every period when timer started or just affect it ocassionally.

RE: NRF52840 when using Timer and BLE services I found a problem

Kenneth — Thu, 07 Jan 2021 12:27:06 GMT

The BLE can affect the timing, but not by 10ms, the difference is more like ~100us.

The code you refer to disable and enable the timer, you are not starting or stopping the timer somewhere also?

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Thu, 07 Jan 2021 01:51:25 GMT

I comment out the places that I start the timer by accident, but the timer still varies occasionally.

and I found that when I didn't start the ble and use the timer only, the timer wouldn't vary. However, when I start the ble and then open the timer, it will wary occasionally. So I thought that whether the ble will affect the timer?

RE: NRF52840 when using Timer and BLE services I found a problem

Kenneth — Wed, 06 Jan 2021 11:06:42 GMT

I would double check that you don't by accident stop/start the timer here somewhere in your code, for instance for test you can comment out all places where stop/start are done today.

Kenneth

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Wed, 06 Jan 2021 01:20:26 GMT

it varies and the next period will be 320ms, it just occasionally turns to 330ms. I stop or start the timer when ble disconnected or connected.

it's random and I found that when only enable the timer and saadc and don't use the ble the timer goes fine.

RE: NRF52840 when using Timer and BLE services I found a problem

Kenneth — Tue, 05 Jan 2021 15:19:41 GMT

This was quite a big delay (320ms->330ms), is it consistently +10ms (330ms) when it occurs or does it vary? Also, what is the next period (310ms or 320ms)?

Are you sure you are not START or STOP timer somewhere in your code?

Kenneth

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Tue, 05 Jan 2021 06:44:28 GMT

I mean that the sample time I need is 320ms and it will be triggered by a hardware timer to ensure its accuracy. However, when I don't change its frequency, It sometimes goes to 330ms which may affect the number of packs I receiving from ble sent to my PC device and that is my problem.

RE: NRF52840 when using Timer and BLE services I found a problem

Henry_Chou — Tue, 05 Jan 2021 06:01:52 GMT

Almost the ble case with softdevice. The examples are applied the RTC1 timer for timer handling ( Because SD occupied RTC0). I re-command that you may refer the time handling example.

app_timer2.c

app_timer_init(()

app_timer_create()

app_timer_start()

app_timer_stop()

or the app_buton.c button timer handling method that can fix your problems.

But I doubt that if the ADC sampling timer is more longer. Why the value accuracy is bad?

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Tue, 05 Jan 2021 02:09:50 GMT

I mean that I put this function after the softdevice enabled but the problem about saadc sample time is still there. I test the period of the saadc sample and it should be 320ms, while when using the ble services it will jump to 330ms ocassionally.

RE: NRF52840 when using Timer and BLE services I found a problem

Kenneth — Mon, 04 Jan 2021 10:39:46 GMT

I am not sure what you mean by it doesn't work. Does the sd_clock_hfclk_request() return an error? Are you calling this function after softdevice is enabled or are you not using a softdevice?

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Mon, 04 Jan 2021 05:32:52 GMT

it doesn't work

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Wed, 30 Dec 2020 09:20:37 GMT

I have not used this function, should I add it to the main?

RE: NRF52840 when using Timer and BLE services I found a problem

Kenneth — Wed, 30 Dec 2020 09:16:30 GMT

Have you also started the external hfclk by calling sd_clock_hfclk_request()?

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Wed, 30 Dec 2020 08:54:38 GMT

and start TIMER in the ble_evt_handler function

RE: NRF52840 when using Timer and BLE services I found a problem

zk12312 — Wed, 30 Dec 2020 08:49:51 GMT

void saadc_sampling_event_init(void)
{
	  ret_code_t err_code;
	 // uint32_t time_ticks=53028;	
    uint32_t time_ticks=53672;//3.33ms tick=53328 TIME3=16MHZ,1ms tick=16000	
	
    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);
	  	
    nrf_drv_timer_config_t timer_cfg = NRF_DRV_TIMER_DEFAULT_CONFIG;
	  
    err_code = nrfx_timer_init(&TIMER_ADC, &timer_cfg, timer_adc_event_handler);
    APP_ERROR_CHECK(err_code);
   
    nrf_drv_timer_extended_compare(&TIMER_ADC, NRF_TIMER_CC_CHANNEL3, time_ticks, NRF_TIMER_SHORT_COMPARE3_CLEAR_MASK, true);
	   uint32_t timer_compare_event_addr = nrf_drv_timer_compare_event_address_get(&TIMER_ADC,
                                                                                NRF_TIMER_CC_CHANNEL3);
	
    uint32_t saadc_sample_task_addr   = nrf_drv_saadc_sample_task_get();
    err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
    APP_ERROR_CHECK(err_code);
	
	  err_code = nrf_drv_ppi_channel_assign(m_ppi_channel,
                                          timer_compare_event_addr,
                                          saadc_sample_task_addr);
																					
		APP_ERROR_CHECK(err_code);	 																		
}

this is my code about Timer and ppi init

RE: NRF52840 when using Timer and BLE services I found a problem

Henry_Chou — Wed, 30 Dec 2020 02:31:30 GMT

May you show your create timer ,start timer ,stop timer & timer callback handler procedure?

Have you ever trigger timer with repeat mode?