52832 COMP — Comparator

[K-night]

hi, I want to use 52832 Comparator function, SDK only has "low power comparator" demo code. Setting reference voltage in MCU, just compare one GPIO with this voltage.

But I want to use "differential mode"(set two GPIOs as "AN+", “AN-”, compare two GPIO's voltage), "high speed" mode, could you provide some demo code for my requirement? I don't know how to write code for setting my requirement.

thanks 

[JONATHAN LL]

Hi,

What SDK are you using and what version of the SDK?

Regards,
Jonathan

[K-night]

17.1.0 SDK, LPCOMP demo code

[K-night]

And I used your "lp-comp" demo code, connected pin 0.02 to GND, can't into interrupt, could you help me to check where I should change it? I want to print"LPCOMP_EVENT_UP" when pin 0.02 connected VCC,  print"LPCOMP_EVENT_DOWN" when pin 0.02 connected GND.

thanks  

static void lpcomp_event_handler(nrf_lpcomp_event_t event)
{
    if (event == NRF_LPCOMP_EVENT_DOWN)
    {
//        bsp_board_led_invert(BSP_BOARD_LED_0); // just change state of first LED
//        voltage_falls_detected++;
//        voltage_falls_total++;
				printf("\r\nLPCOMP_EVENT_DOWN\r\n");
    }
	  else if (event == NRF_LPCOMP_EVENT_UP)
    {
				printf("\r\nLPCOMP_EVENT_UP\r\n");
    }
		bsp_board_led_off(BSP_BOARD_LED_0);
		printf("\r\nlpcomp_event_handler\r\n");
}


/**
 * @brief Print out detection statistics.
 */
static void print_statistics(void)
{
    while (voltage_falls_detected)
    {
        voltage_falls_detected--;
        //NRF_LOG_INFO("#%d fall detected", (int)voltage_falls_total);
				printf("\r\nfall detected = %d\r\n",(int)voltage_falls_total);
    }
}


/**
 * @brief Initialize LPCOMP driver.
 */
static void lpcomp_init(void)
{
    uint32_t                err_code;

    nrf_drv_lpcomp_config_t config = NRF_DRV_LPCOMP_DEFAULT_CONFIG; // <3>---4/8 of 1.8V = 0.9V, <2>---down, lower 0.9V into interrupt
    config.input = NRF_LPCOMP_INPUT_2;															// <2>---P0.02
    // initialize LPCOMP driver, from this point LPCOMP will be active and provided
    // event handler will be executed when defined action is detected
    err_code = nrf_drv_lpcomp_init(&config, lpcomp_event_handler);
    APP_ERROR_CHECK(err_code);
    nrf_drv_lpcomp_enable();
	
}



int main(void)
{
	 uint32_t err_code;
	
	  NRF_CLOCK->EVENTS_HFCLKSTARTED=0;
	  NRF_CLOCK->TASKS_HFCLKSTART=1;
	  while(NRF_CLOCK->EVENTS_HFCLKSTARTED==0)
		{
		}
		
    const app_uart_comm_params_t comm_params =
      {
          RX_PIN_NUMBER,
          TX_PIN_NUMBER,
          RTS_PIN_NUMBER,
          CTS_PIN_NUMBER,
          UART_HWFC,
          false,
#if defined (UART_PRESENT)
          NRF_UART_BAUDRATE_115200
#else
          NRF_UARTE_BAUDRATE_115200
#endif
      };

    APP_UART_FIFO_INIT(&comm_params,
                         UART_RX_BUF_SIZE,
                         UART_TX_BUF_SIZE,
                         uart_error_handle,
                         APP_IRQ_PRIORITY_LOWEST,
                         err_code);

    APP_ERROR_CHECK(err_code);

#ifndef ENABLE_LOOPBACK_TEST
    printf("\r\nCOMP example started.\r\n");
#endif	   
	
	
    bsp_board_init(BSP_INIT_LEDS);

    nrf_gpio_cfg_output(WAVE_ON_PIN_NUMBER); // on this pin 2Hz wave will be generated

//#ifdef BSP_BUTTON_0
//    // configure pull-up on first button
//    nrf_gpio_cfg_input(BSP_BUTTON_0, NRF_GPIO_PIN_PULLUP);
//#endif

//    uint32_t err_code1 = NRF_LOG_INIT(NULL);
//    APP_ERROR_CHECK(err_code1);

//    NRF_LOG_DEFAULT_BACKENDS_INIT();

    lpcomp_init();

		//bsp_board_led_on(BSP_BOARD_LED_0);
	
    while (true)
    {
//        print_statistics();
//        bsp_board_led_on(BSP_BOARD_LED_1);
//        NRF_GPIO->OUTCLR = (1 << WAVE_ON_PIN_NUMBER);
//        nrf_delay_ms(100); // generate 100 ms pulse on selected pin
//        print_statistics();
//        bsp_board_led_off(BSP_BOARD_LED_1);
//        NRF_GPIO->OUTSET = (1 << WAVE_ON_PIN_NUMBER);
        //nrf_delay_ms(1000);
        //NRF_LOG_FLUSH();
			
			//printf("\r\nUP\r\n");
			//bsp_board_led_on(BSP_BOARD_LED_0);
    }
}

 

[K-night]

Could you tell me what is the fastest sampling frequency for “Comparator different and high speed” mode?

My "AN+" connected 10K hz 1.8V square wave, "AN-" connected 1.25V, but the output pin didn't output, I think frequency is faster than MCU comparator. thanks 

 

[Sigurd]

Hi,

Looking at the LPCOMP chapter in the PS,  https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/lpcomp.html?cp=4_2_0_38_3_0#unique_1187726518 , 

We have that "Time from VIN crossing (>=50mV above threshold) to ANADETECT signal generated." is typ 5us, i.e. max frequency is 200kHz.

K-night said:

My "AN+" connected 10K hz 1.8V square wave, "AN-" connected 1.25V, but the output pin didn't output, I think frequency is faster than MCU comparator. thanks 

Could you show the code you use for this?