Trigger lpcomp sampling doesn´t work

[Kampino]

Hello,

I try to modify the lpcomp example from the Nordic SDK to trigger the sampling of the lpcomp manually. I have added the following code:

lpcomp_init();

NRF_LOG_INFO("LPCOMP driver usage example started.");

nrf_lpcomp_task_trigger(NRF_LPCOMP_TASK_START);
nrf_lpcomp_task_trigger(NRF_LPCOMP_TASK_SAMPLE);
while(!nrf_lpcomp_event_check(NRF_LPCOMP_EVENT_READY));
Result = NRF_LPCOMP->RESULT;

I use AIn3 (GPIO 5) as input for the lpcomp and the input voltage is 2.4 V. The limit is set to 4/8 Vcc, but the result is 0 and not 1 as expected.

What is the issue with this code?

[Kenneth]

Does the default lpcomp example from nRF5 SDK work as expected? Does using a different analog input work?

Kenneth

[Kampino]

Hi,

the default example works without any issue (with the same input). Changing the input pin doesn´t change anything.

[Kenneth]

Is it possible that you have provided a callback handler in lpcomp_init() that is already doing this for you?

Kenneth

[Kampino]

Hi,

I have set a breakpoint in the callback handler from the application code, but this breakpoint doesn´t get triggered. I will try to set the breakpoint in the ISR of the lpcomp driver and check it again.

[Kampino]

Hi Kenneth,
there is no interrupt triggered.

[Kenneth]

Maybe you can try this bare metal example:
https://github.com/andenore/NordicSnippets/blob/master/examples/lpcomp/main.c 

[Kampino]

Hi Kenneth,
it seems to work now. I think there was an issue with the debugger because I got the correct results after attaching an LED to the result of the lpcomp. I use the initialization from the sdk example with the following loop:

    while (true)
    {
        NRF_LPCOMP->TASKS_SAMPLE=1;
	    while(!nrf_lpcomp_event_check(NRF_LPCOMP_EVENT_READY));
        if(NRF_LPCOMP->RESULT)
        {
            bsp_board_led_on(BSP_BOARD_LED_1);
        }
        else
        {
            bsp_board_led_off(BSP_BOARD_LED_1);
        }
    }