Sofirn SC31 Pro UPDI Flash Adapter

If you want to update the firmware of your Sofirn SC31 Pro and you had a newer revision with exposed UPDI pads, you can use this adapter with pogo pins to easily flash a new firmware to your Sofirn SC31 Pro.

Print instructions

Printed Parts 

• 1x Print Flash Adapter

Notes on printing

• Layer height: 0.1mm
• Filament: PLA

Additional Parts 

• 3x Pogopin/Spring Test Pin P75-J1 1.0x16.5mm
• 1x Wire Cable 30AWG 
• 1x 2.54mm Female Breakable Pin Header
• 1x DIY UPDI Programmer
  • 1x Arduino Nano
  • 1x Resistor 1% 2W 4.7K
  • 1x SMD 10 uF ceramic capacitor
  • 1x 6-Pin angled header

Build instructions

1. Print Flash Adapter
2. Wire the Adapter (see pictures)
   • Left (R on the PCB, orange in the picture) to UPDI D 
   • Center (no marking on the PCB, back on the picture) to UPDI GND/-
   • Right (+ on the PCB, red on the picture) to UPDI VCC/+

Flash instructions

• First: No warranty is for this guide. Use at your own risk.
• Check to connection to the MCU of you flashlight. Replace <serial-port> with the UPDI serial port on your platform like COMx or /dev/ttyUSBx. Depending on your UPDI programmer, maybe you need to change jtag2updi to updiserial.

❯ .\avrdude -p attiny1616 -c jtag2updi -P <serial-port> /-n
avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9421 (probably t1616)

avrdude done.  Thank you.

• If this not work, check the connection or you UPDI programmer

❯ .\avrdude -p attiny1616 -c jtag2updi -P <serial-port> -n
avrdude error: UPDI link initialization failed
avrdude error: initialization failed, rc=-1
        - double check the connections and try again
        - use -b to set lower baud rate, e.g. -b 57600
        - use -F to override this check

• Backup the old Firmware

❯ .\avrdude -p attiny1616 -c jtag2updi -P <serial-port>  -Uflash:r:old-firmware.hex
avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9421 (probably t1616)

avrdude: processing -U flash:r:old-firmware.hex:r
avrdude: reading flash memory ...
Reading | ################################################## | 100% 3.37 s
avrdude: writing output file old-firmware.hex

avrdude done.  Thank you.

• Flash new Firmware. For the Sofrin SC31 Pro you need the sofirn-sp36-t1616 firmware (identical hardware platform) from the offical repo of ToyKeeper/anduril

❯ .\avrdude -p attiny1616 -c jtag2updi -P com3 -Uflash:w:anduril.r2025-07-07.sofirn-sp36-t1616.hex
avrdude: AVR device initialized and ready to accept instructions
avrdude: device signature = 0x1e9421 (probably t1616)
avrdude: Note: flash memory has been specified, an erase cycle will be performed.
         To disable this feature, specify the -D option.
avrdude: erasing chip

avrdude: processing -U flash:w:anduril.r2025-07-07.sofirn-sp36-t1616.hex:i
avrdude: reading input file anduril.r2025-07-07.sofirn-sp36-t1616.hex for flash
         with 10452 bytes in 1 section within [0, 0x28d3]
         using 164 pages and 44 pad bytes
avrdude: writing 10452 bytes flash ...
Writing | ################################################## | 100% 2.59 s
avrdude: 10452 bytes of flash written
avrdude: verifying flash memory against anduril.r2025-07-07.sofirn-sp36-t1616.hex
Reading | ################################################## | 100% 2.18 s
avrdude: 10452 bytes of flash verified

avrdude done.  Thank you.

• After flashing do a factory reset.

Links
The links to shops can be advertising links. I would be happy if you use this link, but of course you don't have to. I have linked exactly the offers from which I have also bought and was satisfied with the supplier and the goods. The products can of course be bought anywhere.

Credits

• https://www.pingle.org/2022/08/07/flashing-a-3-pin-t1616-flashlight-with-new-firmware
• https://github.com/ToyKeeper/anduril
• https://daumemo.com/diy-updi-usb-programmer-which-can-be-made-with-cheap-hardware/