The old Bluepill with CM4F F303CC..

[iMo]

FYI - I found couple of stm32F303CBs in my junkbox thus I could not resist the temptation so I spent couple of minutes with a soldering job.. The Cube programmer can flash it with full 256kB of flash (it is a CC silicon, as usual..), and it works at 128MHz here as well.

You will get a Cortex M4F (with the single precision FPU and an MPU), 4x 5Msps 12b ADCs (ie 2 with simultaneous sampling), 2ch 12b DAC, etc, etc.

Limitation - sadly the USB clock divider in this chip is 1.5 max so no USB beyond 72MHz. Also the active header is the one with the jumper there on the below picture (it sets the USB downloader active, you have to keep the reset button pressed during power-up in order to flash the binary in via the USB).