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The board uses a STM32, and requires a ST-Link to program. The process used to upload code to the MCU is the same as the Vaisala RS41 radiosonde, you will need to solder and connect the VTRef(3.3V), Ground, SWDIO, SWDCLK and RST pins to your ST-Link. You can also try using a [https://www.printables.com/model/594752-dfm17-swd-programming-jig-clip-thing 3d printed jig] to hold a connector on the board for solderless programming. The board can run without external power being supplied when programming. This board has read-out protection enabled similar to the RS41 and this must be disabled before you can flash firmware to the board. ==Software== A few attempts have been made to build replacement firmware for these devices, the key goal being to be able to re-fly a sonde as an amateur payload. There was an early attempt called dfm17_hamradio [https://github.com/gx1400/dfm17_hamradio here] and [https://github.com/trickv/dfm17_hamradio/tree/aprs-fifo-gps-superhacky here]. The most mature looking effort is [https://github.com/mikaelnousiainen/RS41ng RS41ng] which has experimental support.