diy single sided pcb for serprog based flash programmer for flashrom.
On this pcb arduino pro mini is powered with 3.3v and used with a 3.3v usb serial adapter such as https://github.com/acemielektron/FT230X_usb_serial_PCB otherwise 3.3v parts might fry.
Serprog home page: https://www.flashrom.org/Serprog/Arduino_flasher