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Tools · Level 1 & Level 2

CH341A Setup

The CH341A is the little USB programmer that reads and writes the EEPROM chips in this contest. Here's how to get it talking to our browser-based programmer on your own computer. The booth laptops are already set up.

Tools EEPROM Programmer CH341A Setup CyberChef

The Hardware

Both levels use the same small USB module, just with different things plugged into its socket. Level 1 uses a chip clip (see the clipping-on tips). For Level 2, a small adapter plugs into the socket and your minibadge plugs into that, so you don't have to fight a chip clip while writing data.

CH341A USB EEPROM programmer board
CH341A Programmer The module itself: same board for both levels.
Photo coming soon
Level 2 Minibadge Adapter Borrow one at the booth. It plugs into the CH341A's socket and your minibadge plugs into it.

Driver Setup

The programmer runs in Chrome, Edge or Opera using WebUSB, which lets a web page talk to a USB device you pick. Firefox and Safari don't support it. Each operating system needs a slightly different one-time step:

Windows: install WinUSB with Zadig

Windows gives the CH341A a driver that a web page can't use. Swap it for WinUSB once per computer (the same fix as the logic analyzer's driver setup):

  1. Plug in the CH341A

    Leave the mode jumper where it came from the factory.

  2. Open Zadig

    Download it from zadig.akeo.ie. Choose Options → List All Devices, then pick the device whose USB ID is 1A86 5512. It may be called "USB UART-LPT" or "CH341A". Double-check the ID so you don't replace the driver of something else.

  3. Install WinUSB

    Set the target driver to WinUSB and click Replace Driver (or Install Driver). Unplug the CH341A and plug it back in.

Linux: add a udev rule

No driver is needed, but by default only root may open the device. Let your user open it, then unplug and replug the programmer: 

echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="1a86", ATTR{idProduct}=="5512", MODE="0666"' \
  | sudo tee /etc/udev/rules.d/50-ch341a.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

macOS

Nothing to install: Chrome or Edge can use the CH341A directly. If you installed WCH's serial-port driver at some point, it only affects the CH341 in serial mode and doesn't get in the way.

Programmer not showing up? If its red LED is dim or it disappears the moment a chip goes in, the chip is in backwards and is shorting the power: unplug USB right away and turn the chip around. Also close any other program (or browser tab) that's using the CH341A; only one can hold it at a time.

Plugging In a Chip

  1. Unplug USB first

    Put chips (or the clip or minibadge adapter) in and take them out with the programmer unpowered.

  2. Use the 24XX positions

    8-pin chips use half of the 16-pin socket. 24-series EEPROMs go in the four positions nearer the USB plug (the board's printed 25XX | 24XX marking shows which half), with pin 1 (the dot or notch) toward the lever. Push the lever down to clamp it.

  3. Check the LED

    Plug USB back in. The POWER LED next to the USB plug should be bright. Dim means backwards: unplug and fix it.

With a chip clip, the red wire goes to pin 1 (the dot on the chip). The programmer page has the same tips under "How to plug it in".

Using the Programmer

Open the EEPROM Programmer

The EEPROM programmer after reading a 128-byte chip: hex table with ASCII text on the right, chip detected as AT24CS01, chip and table marked SAME
The programmer after reading a Level 1 chip The hex table shows every byte, with the readable text alongside.

  1. Start a session

    Give your scratch space a name. Your table is saved in that browser as you go, so you can come back later the same day. Nothing is uploaded, and sessions are cleared daily: save a .bin of anything you want to keep.

  2. Connect

    Click Connect and pick the CH341A in the browser's list. The browser always asks you to choose; after that, the page finds it by itself. The chip is detected as soon as it answers.

  3. Read

    Copies the whole chip into the table (128 bytes from a Level 1 chip, 1024 from your minibadge's) with the text alongside. Select text and copy it, or save it as a file.

  4. Edit and Write (Level 2)

    Type into the table, or load a .bin file, then Write. Changed bytes stay highlighted until they're written or saved. Read your chip first: a good read means your solder joints are good before you write anything.

  5. Verify

    Reads the chip back and compares it with the table: SAME or DIFFERENT, with every differing byte marked. Write verifies automatically unless you turn that off.

Desktop Alternatives

Prefer a desktop program? These work with the CH341A too. They may want a different driver than WinUSB, so follow their own setup instructions. Set the chip type to 24C01 for the Level 1 panel chips and 24C08 for your minibadge.

A Note on Safety

This is about as low-risk as hardware hacking gets: you're reading and writing a 5V logic-level EEPROM, not touching mains voltage. The only real failure mode is a bad connection (bridged solder pins, a slipped chip clip) producing garbage data, which is exactly what reading first and verifying after are there to catch.