STM32Fx PCB with STM32F303RCT7 mounted. This device features:
See https://wiki.newae.com/CW308T-STM32F for technical details.
NOTE: An external programmer is suggested for this target, the recommended one is the ST-LINK/V2 (available for < $25). The wiki page contains examples of using other programmers via OpenOCD. ChipWhisperer release 3.4.4 and later support programming this using the built-in bootloader.