Flashing the FNIRSI HS-01

This procedure also applies to the KAIWEETS KETS02. It is the same board and uses the same HS01 build.

The CH571 MCU has a ROM bootloader. Use wchisp to flash IronOS through it. You cannot erase the ROM bootloader. If a flash fails, you can always do it again.

Before you start

  • Flashing IronOS removes the vendor updater (the left-button bootloader). After this, the vendor update tool does not work.
  • The vendor firmware has read-out protection. You cannot make a backup of it from the iron.

Procedure

  1. Install wchisp. Use a release binary from its GitHub page, or run cargo install wchisp.
  2. Disconnect the iron.
  3. Start this command on the computer. It waits for the bootloader, then flashes the file:

sh until wchisp info >/dev/null 2>&1; do sleep 0.4; done; wchisp flash HS01_EN.bin

  1. Push and hold the right button.
  2. Connect the iron to the computer with the USB-C cable.
  3. Release the button after 2 seconds.
  4. Wait for the message Verify OK.
  5. Disconnect the iron and connect it to a USB-C PD charger.

The bootloader stays active for approximately 7 seconds only. If the flash does not start in that time, do steps 2 to 6 again.

After Verify OK, wchisp can stop at the device reset. This is not a problem. The flash is complete.

On Linux, a udev rule for the bootloader is possibly necessary (USB ID 4348:55e0 or 1a86:55e0). Alternatively, run wchisp with sudo.

After flashing

  • The left button (near the tip) is + and the right button is -. This is the IronOS standard. To swap them, use the reverse +/- setting.
  • IronOS cannot read the current that the charger can supply. If the charger is less than 65 W, set a power limit in the power settings.
  • On USB power from a computer, the iron does not heat. It needs a PD charger.