NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

runsiv — Tue, 29 Jul 2025 13:40:05 GMT

Just an update, the designer in on vacation until Monday. I will update next week

Regards

Runar

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

tesc — Tue, 22 Jul 2025 16:44:44 GMT

Hi,

Thanks for the confirmation. We need to look into whether this is a bug in documentation, and I do hope we can get back to you within a week or two in order to confirm what are the correct formulas.

Regards,
Terje

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Pratik Panchal — Mon, 21 Jul 2025 04:57:03 GMT

Hello Terje,

Thank you for your response.

If we define the threshold levels (UP/DOWN) and compare them with the corresponding voltage, we can easily map them using the following formula: (previous response attached mapping file )

VDOWN = (THDOWN + 1) / 32 * VREF
VUP = (THUP + 1) / 32 * VREF

However, the threshold-to-voltage mapping described in the Comparator documentation does not align with this formula.

Thanks & Regards,
Pratik Panchal

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

tesc — Thu, 17 Jul 2025 14:07:59 GMT

Hi,

Key person is away, and we will need to look back into this when they are back in 2 weeks.

In the interim: Does the thresholds work at the correct levels, if you assume the following formulas for setting the threshold values?

VDOWN = (THDOWN+1)/32*VREF
VUP = (THUP+1)/32*VREF

Regards,
Terje

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Pratik Panchal — Tue, 15 Jul 2025 09:17:17 GMT

Hello Nordic Team,

Could you please answer my query?

Regards,
Pratik

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Pratik Panchal — Thu, 10 Jul 2025 04:00:14 GMT

Hello Kenneth,

Just a quick reminder—have there been any updates or findings regarding my query?

Thanks & Regards,
Pratik

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Pratik Panchal — Mon, 30 Jun 2025 12:48:06 GMT

Hi Kenneth,

Thank you for your response.

I have reviewed the documents you provided and, based on that, I have defined the comparator.

The comparator configuration is provided below in the overlay.

.Overlay

&comp {
	compatible = "nordic,nrf-comp";
	main-mode = "SE";
	psel = "AIN4"; /* P1.11 */
	refsel = "VDD";
	sp-mode = "HIGH";
	th-up = <63>;
	th-down = <31>;//<59>;
	isource = "DISABLED";
	enable-hyst;
	status = "okay";
};

and define the init_comparator() function and the IRQ interrupt. When the threshold is crossed (either upward or downward), the function comp_event_handler() should be invoked.

Code:

//comparator node
static const struct device *test_dev = DEVICE_DT_GET(DT_ALIAS(test_comp));

bool event_flag = true;  //<----------- this flag needed because sometime when we adc fall from up to down then both event triggered down and up

void comp_event_handler(void)
{
   if (NRF_COMP->EVENTS_UP) {
		if(!event_flag)
		{
			printk("\tEVENTS_UP >>>>>> : [%d]\n", NRF_COMP->EVENTS_UP);
        	NRF_COMP->EVENTS_UP = 0;
			NRF_COMP->EVENTS_DOWN = 0;
			event_flag = true;
		}
    }

	if (NRF_COMP->EVENTS_DOWN)
	{
		if (event_flag)
		{
			printk("\tEVENTS_DOWN <<<<<< : [%d]\n", NRF_COMP->EVENTS_DOWN);
			NRF_COMP->EVENTS_DOWN = 0;
			NRF_COMP->EVENTS_UP = 0;
			event_flag = false;
		}
	}

int init_comparator()
{
struct comp_nrf_comp_se_config comp_config = {
		.psel = COMP_NRF_COMP_PSEL_AIN4,
		.sp_mode = COMP_NRF_COMP_SP_MODE_HIGH,
		.isource = COMP_NRF_COMP_ISOURCE_DISABLED,
		.refsel = COMP_NRF_COMP_REFSEL_VDD,
		.th_down = 5, //<---- up threshold  
		.th_up = 16, // <----- down threshold
	};
	comp_nrf_comp_configure_se(test_dev, &comp_config);
	
	// Configure event UP to publish
	NRF_COMP->PUBLISH_UP = COMP_PUBLISH_UP_EN_Enabled;

	// Define handler for event UP
	NRF_COMP->INTENSET = COMP_INTENSET_UP_Msk;

	// Check if the IRQ is already registered before connecting
	if (!irq_is_enabled(DT_IRQN(DT_NODELABEL(comp)))) {
		// Register the interrupt handler
		IRQ_CONNECT(DT_IRQN(DT_NODELABEL(comp)), DT_IRQ(DT_NODELABEL(comp), priority), comp_event_handler, NULL, 0);

		// Enable the interrupt
		irq_enable(DT_IRQN(DT_NODELABEL(comp)));
	} else {
		printk("IRQ %d is already registered.\n", DT_IRQN(DT_NODELABEL(comp)));
	}
	
		// Enable and start COMP
	NRF_COMP->ENABLE = 2;
	NRF_COMP->TASKS_START = 1;
}

Proj.conf

# Comparator
CONFIG_COMPARATOR=y
CONFIG_NRFX_COMP=y
CONFIG_SHARED_INTERRUPTS=y

According to the formula provided in the documentation for the TH threshold registers.

VDOWN = (THDOWN+1)/64*VREF
VUP = (THUP+1)/64*VREF

For example, with a threshold of 5, the expected voltage is 104 mV based on the given formula.

e.g, Threshold = 5
Voltage(mv) = 104

I expected mv value as per the above formula, but it is not.

However, in my testing, I observed:

e.g, Threshold = 5
Voltage(mv) = 168.75

After reverse engineering, I found that the voltage calculation in the system follows this formula:

V = ((TH + 1)/32) * Vref // divided by 32 not 64

Please find attached the log table in .txt.

Could you please clarify what changes or settings are required to achieve the voltage readings as per the formula provided in the documentation?

Thanks & Regards,
Pratik
devzone.nordicsemi.com/.../th_5F00_adc_5F00_tab.txt

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Kenneth — Mon, 30 Jun 2025 11:29:11 GMT

Hi,

Dont' have time to test the code, but make sure you understand the difference between COMP and LPCOMP:
https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/comp.html
https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/lpcomp.html

One can be used in sleep and wakeup the chip (lpcomp), the other is only active while the CPU is running (comp).

Kenneth

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Pratik Panchal — Mon, 30 Jun 2025 11:05:26 GMT

Hello Kenneth

Thank you for your response.

I reviewed the Nordic thread you shared and used the referenced code to configure and integrate a comparator into my application. I connected a potentiometer to the defined ADC pin for input variation.

However, I expected to receive specific up or down events based on the configured threshold up/down values.
I referred to the overlay file from the provided GitHub repository, but despite defining th_up and th_down values, the test_callback function does not increment the count on defined up or down threshold, but it only increments when we fully increase the potentiometer value to 4092 = 0.899V, and the event
bool event = comparator_get_output(test_dev); Returns 1 on 0.899V.

Even I modified the value of th-up to 40, then also the event returns 1 only at 0.899V.

Here, my application overlay for the comparator :

&comp {
	compatible = "nordic,nrf-comp";
	main-mode = "SE";
	psel = "AIN4"; /* P1.11 */
	refsel = "VDD";
	sp-mode = "HIGH";
	th-up = <63>;
	th-down = <31>;//<59>;
	isource = "DISABLED";
	status = "okay";
};

Could you please provide a sample that demonstrates the detailed usage of the APIs for configuring up/down thresholds and handling the corresponding events?

Thanks & Regards,
Pratik Panchal

RE: NRF54L15-DK : ADC Threshold Event Configuration using LPCOMP and ANADETECT

Kenneth — Thu, 26 Jun 2025 11:37:34 GMT

Hi,

I suggest to check out this answer: Using the new LPCOMP driver in Zephyr

Kenneth