nPM1300 TWI not working without J4 (nPM controller) connected

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Scigrapher — Wed, 03 Dec 2025 23:31:29 GMT

The bias-pull-up was it! I didn't notice that in the board overlays in the sample. It's working now. The controller on the nPM1300 was obviously doing this for me and I didn't realize it.

Thank you!

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Elfving — Wed, 03 Dec 2025 14:51:20 GMT

There shouldn't be a need to keep the FG board connected while attempting to connect an external DK atleast. Though if that doesn't help, try to check whether the pull up is enabled on the bus lines. (in DTS this is done by adding bias-pull-up to the i2c30_default config)

And disconnecting the TWI while the SoC is powered up may require a power cycle to get the TWI working again.

Regards,

Elfving

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Scigrapher — Mon, 01 Dec 2025 16:02:25 GMT

Yes, the fuel gauge board is connected. I had previously profiled the battery that I'm now using and I had never disconnected it. Disconnecting the fuel gauge board doesn't fix it. As soon as I disconnect the plug from J4, the nRF54l15DK immediately stops being able to talk to the nPM1300EK.

[00:29:36.433,129] <inf> pmic_npm1300: V: 4.101, I: 0.000, T: 25.10, SoC: 95.03, TTE: 11355182, TTF: nan
[00:30:06.438,149] <inf> pmic_npm1300: V: 4.106, I: 0.000, T: 25.10, SoC: 95.03, TTE: 11446964, TTF: nan
[00:30:36.443,173] <inf> pmic_npm1300: V: 4.101, I: 0.000, T: 25.10, SoC: 95.03, TTE: 11469531, TTF: nan
[00:31:06.943,402] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 0/2
[00:31:07.453,578] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 1/2
[00:31:07.963,752] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 2/2
[00:31:07.973,822] <err> pmic_npm1300: Could not read from charger device (-5)
[00:31:07.973,827] <wrn> ble_services: Battery sample failed (-5)
[00:31:18.473,994] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 0/2
[00:31:18.984,170] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 1/2
[00:31:19.494,372] <wrn> pmic_npm1300: Transient charger read error (err -5), retry 2/2
[00:31:19.504,452] <err> pmic_npm1300: Could not read from charger device (-5)
[00:31:19.504,458] <wrn> ble_services: Battery sample failed (-5)

I was wrong about just reconnecting J4 for it to recover... I need to reconnect and reset the nRF54l15 for communication to resume.

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Elfving — Mon, 01 Dec 2025 07:24:04 GMT

Might be that I am misunderstanding something here, but is the FG board connected to the EK? I am not sure about the reason for that.

First thing to try is disconnecting the FG board and checking then the connection between EK and DK.

Regards,

Elfving

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Scigrapher — Sat, 29 Nov 2025 00:22:16 GMT

"Not sure about my wiring" as in you think it's wrong/bad or that you can't make sense of my pictures/overlay? I admit that I'm trying to put as much relevant info in as I can to help diagnostics, which may be making things more complicated.

I re-wired and ran the sample and it seems to work with or without J4 plugged in, which is another interesting data point. The main problem for me is that pins P1.11 and P1.12 are already in use by a different peripheral. I'm actually running pretty low on usable pins, which is why I'm using P0.03 and P0.04. I'm also already using spi21 and spi22 and spi00 is used for external memory on the DK and uart20 is used by the debugger. i2c30 is the only one still available.

I updated the sample to use i2c30 and P0.03 and P0.04 and it still worked with and without J4 plugged in, so it doesn't seem specific to that configuration. I'd expect it to work: According to clock pins, TWIM's SCL (unsurprisingly) needs to be a clock pin. P0.03 and P0.04 are both clock pins according to Pin assignments, so that should be fine. According to TWIM configuration TWIM30 needs to use port 0, so that lines up. AFAIK, I'm not using any other peripherals with ID 30. I can't think of anything else that I need to check.

If nothing else, the fact that it works when J4 is connected indicates to me that the wiring itself is OK, at least to some degree. It definitely worked with the sample code. That said, I don't know what the problem is, so I'm open to any ideas.

RE: nPM1300 TWI not working without J4 (nPM controller) connected

Elfving — Fri, 28 Nov 2025 12:10:18 GMT

Hi,

I am not sure about your wiring here. Could you try this?

Regards,

Elfving