Hi,
I’m working with nRF54L15 (nRF54L15 DK) using NCS v3.0.2, and I’m facing an issue with ADC channel readings.
I configured the following ADC channels:
-
AIN3 → P1.07
-
AIN6 → P1.13
-
AIN7 → P1.14
Devicetree overlay
/ {
zephyr,user {
io-channels = <&adc NRF_SAADC_AIN3>, /* P1.07 */
<&adc NRF_SAADC_AIN6>, /* P1.13 */
<&adc NRF_SAADC_AIN7>; /* P1.14 */
};
};
ADC configuration
#define ADC_NODE DT_NODELABEL(adc)
static const struct device *adc_dev = DEVICE_DT_GET(ADC_NODE);
void adc_init(void)
{
if (!device_is_ready(adc_dev)) {
printk("ADC device not ready\n");
return;
}
struct adc_channel_cfg ch_cfg = {
.gain = ADC_GAIN_1,
.reference = ADC_REF_EXTERNAL0,
.acquisition_time = ADC_ACQ_TIME_DEFAULT,
.differential = 0,
};
uint8_t ain_map[3] = {3, 6, 7}; // AIN3, AIN6, AIN7
for (int i = 0; i < 3; i++) {
ch_cfg.channel_id = i;
ch_cfg.input_positive = ain_map[i];
int ret = adc_channel_setup(adc_dev, &ch_cfg);
if (ret) {
printk("Channel %d setup failed: %d\n", i, ret);
return;
}
}
}
ADC read
void Read_adc_values(void)
{
int16_t raw_buf[3];
struct adc_sequence sequence = {
.channels = BIT(0) | BIT(1) | BIT(2),
.buffer = raw_buf,
.buffer_size = sizeof(raw_buf),
.resolution = 12,
};
int ret = adc_read(adc_dev, &sequence);
if (ret) {
printk("ADC read failed: %d\n", ret);
return;
}
printk("CH0 (AIN3 / P1.07): %d\n", raw_buf[0]);
printk("CH1 (AIN6 / P1.13): %d\n", raw_buf[1]);
printk("CH2 (AIN7 / P1.14): %d\n", raw_buf[2]);
}
Observed behavior
When connecting the sensor:
-
On P1.13 (expected AIN6) → only AIN7 channel shows valid readings
-
AIN3 and AIN6 always return ~4092 (full-scale)
Example output:
CH0 (AIN3 / P1.07): 4092
CH1 (AIN6 / P1.13): 4092
CH2 (AIN7 / P1.14): 2532
Additionally:
-
Connecting the sensor to P1.07 or P1.14 does not change readings
-
Only P1.13 seems to affect ADC output, but it appears on AIN7
Questions
- What is the correct AIN - GPIO mapping for nRF54L15 DK?
- Are P1.07 and P1.14 valid ADC input pins?
- Is any additional configuration required for ADC inputs on nRF54?
Any guidance on correct ADC channel pin mapping for nRF54L15 would be very helpful.
Thanks!
