megi's PinePhone Development Log RSS


2022–01–31: Pinephone Pro battery charging

If you have trouble chargigng battery on Pinephone Pro, this article may help you underastand what may be wrong. First, here are a few quick facts you should know about the Pinephone Pro Type-C port and the power management chip (RK818), to better understand how it all works together:

This is basically it. Most charging issues revolve around setting this one limit. How could that possible be, that there are seemingly so many issues then? :)

How does input power limitting work

So as you can see, if the phone decides it will take no power from the USB power supply, there will simple be not enough power to charge the phone's battery, or even to boot and run the phone. All the charging issues revolve around this one variable: power input limit.

How then does the phone decide what power input limit to set?

Phone startup process

You most probably have some software on the phone, right? :) Therfore:

Let's assume all went well up to this point. Next:

Input power limit negotiation

So how does this detection work?

This is where it gets complicated. Dumb charger detection and Type-C port management are two independent processes with independent hardware signals. Nevertheless, the output of the detection process has to be just one number (power input limit). So these processes have to meet somewhere to decide which one is right and which one will choose the final value for the limit.

So if you:

And this is where most of the software issues were or are.

Type-C software support issues

Let's list some of those issues that I know about at this time: