A Hackaday.io page screenshot, showing all the numerous CH552 projects from [Stefan].

All The USB You Can Do With A CH552

Recently, you might have noticed a flurry of CH552 projects on Hackaday.io – all of them with professionally taken photos of neatly assembled PCBs, typically with a USB connector or two. You might also have noticed that they’re all built by one person, [Stefan “wagiminator” Wagner], who is a prolific hacker – his Hackaday.io page lists over a hundred projects, most of them proudly marked “Completed”. Today, with all these CH552 mentions in the Hackaday.io’s “Newest” category, we’ve decided to take a peek.

The CH552 is an 8-bit MCU with a USB peripheral, with a CH554 sibling that supports USB host, and [Stefan] seriously puts this microcontroller to the test. There’s a nRF24L01+ transceiver turned USB dongle, a rotary encoder peripheral with a 3D-printed case and knob, a mouse wiggler, an interface for our beloved I2C OLED displays, a general-purpose CH55x devboard, and a flurry of AVR programmers – regular AVRISP, an ISP+UPDI programmer, and a UPDI programmer with HV support. Plus, if USB host is your interest, there’s a CH554 USB host development board specifically. Every single one of these is open-source, with PCBs designed in EasyEDA, the firmware already written (!) and available on GitHub, and a lovingly crafted documentation page for each.

[Stefan]’s seriously put the CH552 to the test, and given that all of these projects got firmware, having these projects as examples is a serious incentive for more hackers to try these chips out, especially considering that the CH552 and CH554 go for about 50 cents a piece at websites like LCSC, and mostly in friendly packages. We did cover these two chips back in 2018, together with a programming guide, and we’ve seen things like badges built with its help, but having all these devices to follow is a step up in availability – plus, it’s undeniable that all the widgets built are quite useful by themselves!

A Head Unit Docking Station


[Ivan] had a simple idea: being able to control his Android device from the small keypad on his car’s steering column. This would allow him to cycle through apps, navigation, and audio tracks while never taking his hands off the wheel. Feature creep then set in and [Ivan] asked himself how he could charge his phone through the same interface. What he ended up with is a head unit that’s also a dock.

While [Ivan]’s steering wheel doesn’t have the nice integrated remote control buttons found in newer cars, he does have a Blaupunkt remote, a small, clip-on controller that has a an IR transmitter on it. The IR receiver was connected to a PIC microcontroller, sending commands to the phone for up, down, left, right, menu, and home. Audio output from the phone is handled by a small USB sound card connected to a USB hub, sending the audio signals directly into the head unit’s amplifier.

Having the phone charge while it’s still in USB host mode is the crucial part of this build; not being able to charge on a long car ride would quickly drain the battery and make a car dock kind of pointless. To accomplish this, [Ivan] simulated a Galaxy S4 dock with a few resistors in the USB port, allowing the phone to control the USB sound card, listen to the emulated keyboard and mouse, and charge at the same time.

It’s not a pretty build, but it is extraordinarily useful. In the videos you can see that [Ivan] pretty much pulled this build together from stuff he had sitting around – a great reuse of junk, and a great addition to his car at the same time.

Continue reading “A Head Unit Docking Station”