[nRF5340/nPM1304] Fail to configure PMIC charge current

RE: [nRF5340/nPM1304] Fail to configure PMIC charge current

Kazi Afroza Sultana — Wed, 11 Mar 2026 12:19:09 GMT

Hello Kevin,

I have following explanation from team.

By "measuring the charging current" we actually mean using an external ampere-meter to check the actual current flowing into and out of the battery.

The problem with reading the ADC (or the Zephyr npm13xx sensor driver) value is that it, unfortunately, doesn't take the actual charging current setting into account when calculating the return value. In Zephyr, the current range is taken from the Device Tree setting. It uses the DTS setting `current-microamp` for calculating the "full scale" value which it uses to then calculate the current measured by the ADC. When the charging current is changed by direct register writes, the sensor driver is not aware of this, so it keeps showing the same value due to the same "full scale" value.

Hopefully, this makes it clear.

RE: [nRF5340/nPM1304] Fail to configure PMIC charge current

Kevin Lin — Sat, 07 Mar 2026 03:33:41 GMT

Hi,

Sorry for the late reply; I wasn't in the office the past few days.

Yes, I did measure the current, and it was similar to the value I read. Sorry, I didn't quite understand your explanation of the ADC. I'm not sure if it's using the ADC value; I ported the npm13xx_fuel_gauge example to my custom code and then directly checked the current value.

What's the difference between this method and reading an ADC value?

Best regards,
Kevin

RE: [nRF5340/nPM1304] Fail to configure PMIC charge current

Kazi Afroza Sultana — Sat, 28 Feb 2026 21:46:10 GMT

Hello,

Have you measured the charging current? Or you are relying on the current ADC reading?

Note the current ADC full scale current scales with the charging current set. :"When charging, the full-scale current is the weighted sum of registers BCHGISETMSB and BCHGISETLSB multiplied by 1.25." So basically you would get always the same reading from the ADC if you change the charging current.

RE: [nRF5340/nPM1304] Fail to configure PMIC charge current

Kevin Lin — Thu, 26 Feb 2026 06:26:37 GMT

Hi Kazi Afroza Sultana ,

The BCHGISET value will be one of the following: 0x07 (3.5mA), 0x0A (5mA), 0x0E (7mA), 0x13 (9.5mA), 0x1A (13mA), 0x23 (17.5mA), 0x4C (38mA), 0x6A (53mA), and 0x8C (70mA).

I have not set a value for VBUSINILIM0, so it should be using the default value. The value I read back is 0x01, which, according to the nPM1304 datasheet, corresponds to 100 mA.

Therefore, could I assume that the maximum input current limit is set to 100 mA? However, all desired charging current values are below this maximum.

Thank you very much for your help!

Best regards,
Kevin

RE: [nRF5340/nPM1304] Fail to configure PMIC charge current

Kazi Afroza Sultana — Wed, 25 Feb 2026 14:13:12 GMT

Hello Kevin,

The steps you followed is correct. What is the BCHGISET value you set in the code? The BCHGISET register value is 0x8.

What value you selected for VBUSINILIM0?