Hi all,

I didn't really see much open-source PD firmware for cheap power meters, so I decided to take matters into my own hands and wrote my own. It's mainly for the KOWSI KWS-X1, but I purposely split it into 3 repos so other people can adapt it to their own devices:

• kws-x1-standalone-rs: the actual firmware for the meter (screens, buttons, settings, the PD sink logic) https://github.com/kralonur/kws-x1-standalone-rs
• hc32f460-embassy-rs: an async Embassy HAL for the HC32F460 chip the meter runs on, usable on any board with that MCU https://github.com/kralonur/hc32f460-embassy-rs
• embedded-charging-protocols-rs: no_std USB PD protocol bits that don't care which chip you use https://github.com/kralonur/embedded-charging-protocols-rs

It does the usual meter stuff: voltage, current and power, plus asking the charger for a fixed or PPS voltage. It also has a 5A cable test, and it remembers your settings after a power cycle. The part I'm happiest with is how much PD info it shows. Most cheap meters just say "PD 20V" and that's it. This one shows the charger's full offer (EPR included), its ratings and live status, and the cable's e-marker decoded field by field. It also shows every step of the negotiation, so when a charger acts weird, you can actually see where. You can also put it between a charger and your phone and watch what they say to each other. The full list is in the README.

Now the honest part, because it definitely has its minuses. It's PD only for now, so no QC, AFC or FCP. It can see EPR offers but can't actually go above 20V yet. There's no mAh/Wh counting, no graphs, no logging and no app, and there's no calibration setting either. It forgets your chosen voltage on reboot and always starts at 5V, and flashing only works from Linux right now. I've also only tested it with the chargers and cables I have, so there are surely bugs I haven't hit yet.

I'm planning to add EPR, QC and other protocols in the future, but I can't put all my time into this project, so it will go step by step. That's the good part of open source, though: anyone can jump in and contribute or change the code however they like, and PRs are very welcome.

Getting into the bootloader is easy: hold Back + OK while plugging it into your PC. The README has the full flashing steps and a checklist for testing it by hand.

Disclaimer: Flash at your own risk. I'm not responsible if you damage your device.

AI disclaimer: I used AI tools while working on this. Credit where credit's due. That said, this is far from a vibe-coded project. I followed the official documentation the whole way: the USB PD spec, the chip datasheets and the HC32F460 reference manual. The code isn't a 1:1 copy of those docs, but every protocol value and register setting comes from them, not from guessing. I also tested everything on the real device myself as much as I could.

Some questions I expect:

Why tho?

Why not. The KWS-X1 was cheap enough and capable enough to show a lot of data and talk PD properly, so it made sense.

Will it work on my meter?

If it's a KWS-X1, yes. If it's something else, not necessarily, but that's exactly why the repos are split. If your meter uses an HC32F460, the HAL repo is a good start. The PD protocol repo doesn't care about the chip at all.

Can I go back to stock firmware?

Yep, I tested it myself. To enter the bootloader, hold Back + OK while plugging it into your PC, and then flash the stock image back. Everything worked, triggering included. I found the stock firmware through this blog post: https://tomoca2.hatenablog.com/entry/2026/02/15/221952 (just to be clear, I'm not associated with the author in any way, I just found it useful).

Why Rust?

Idk I like the language and I wanted to. Embassy also makes embedded development really pleasant, and Rust's type system catches a lot of mistakes before they ever reach the device. PD has plenty of states you really don't want to get wrong.

Git history not that old?!

Yep. At first, I did everything in one monorepo, with all development in one place. It got messy, and the history ended up being hundreds of messy commits. Separate repos with a clean history just made more sense.

Repo: https://github.com/kralonur/kws-x1-standalone-rs

So this is what I've got so far. Happy to hear feedback.

Edit: Added cross compiled flasher

Edit 2: Ready-to-flash firmware is now available too, so you don’t have to build anything. Download the firmware and the flasher for your OS, verify the checksums, and follow the README. No installation needed.

Both under: https://github.com/kralonur/kws-x1-standalone-rs/releases/

Hi everyone! I wanted to share a project I just finished — converting my Braun trimmer's charging stand from its proprietary connector to USB-C. My main goal was to reduce the number of power bricks I need and unify everything on USB-C.

Here's what I did:

1. Checked the specs of the original Braun power supply and the trimmer itself. Realized that 5V would be more than enough.
2. Ordered a simple USB-C PD trigger board set to 5V.
3. Disassembled the charging stand that came with the kit. Took measurements and 3D-printed a small plug to fit the old connector hole.
4. Soldered two wires. Put heat shrink on the USB-C board, soldered the wires to the stand's contacts (I checked polarity with a multimeter first, using the original power brick as reference). Inserted it into the 3D-printed plug and sealed the opening with silicone to keep it secure.

Tested it — works perfectly. I'm really happy I could pull this off with my own hands. I love USB-C.

Now I can charge it from any USB-C PD charger I already have.

Hello, first post here. Just wanna share this charger info to others as its release in July 2026 but relatively few reviews. This is UGREEN new 100w compact charger model X880. As you can see in image 4 and 5, this is small compared to Apple 70w Power Adapter. So I was curious to see how good this 100w charger if its this small relative to the power.

Thanks to u//N8falke as I will reference their post https://www.reddit.com/r/ChargingSheet/s/qbQT3jpS7k as they were the only one who review it but in German and I wanna spread it to more people.

To get things out the way, no, this charger can only manage 100w for 20-30 minutes in ideal 24C room temperature. After that the casing gets to 70C+ and throttles to 80w and stays there. Its similar to Apple 40w Dynamic Power to 60w. This is just basically 80w that boost to 100w.

As for the Specs:

USB PD 3.2 (5V 3A / 9V 3A/ 12V 3A / 15V 3A / 20V 5A)

PPS (5V - 21V 5A/ 5V - 11V 5A/ 5V - 21V 4A)

AVS SPR (9-20V 3A, 5A)

Others (PD3.2, QC3, Apple2,4A, DCP)

As you can see, yes it supports Samsung S26 Ultra full 60w, Pixel 9-11 Pro full wattage and many other Chinese Phones. Also one of the few chargers with AVS SPR so it supports iPhone 18 Pro series full charging too.

As for the price, it cost around $50, but I manage to get on sale for $19. So not bad for a single port charger. Not a big fan on multiple port charger anyway.

I was surprised to see that the Walmart brand of ONN usb c multi port chargers are ETL certified. I am looking for a charger that can do multiple ports at 20w for kids iPads and phones. 20w charging is plenty fast for us.

https://www.walmart.com/ip/783499820?sid=FB35C4E5-83E7-4E9E-ABB5-C5F5BB116C53

https://www.walmart.com/ip/14816653362?sid=D89981B9-A5A6-469A-A6F5-BDEAF634DF76

How does this community feel about these chargers? I noticed they are not GaN , does that matter if charging multiple devices at 20w?

Anything else that is cost competitive with these? I know there are several cheaper brands on Amazon where I can get faster charging but I can’t verify that those are ETL certified