This week’s Red Hot PCB comes from OpenMV and is a anniversary gift for his wife. This MiniMe uses an STM32F042, because it is a “crystal-less” USB MCU (meaning it supports USB without needing crystal) so less parts to worry about. Also this MCU has a built-in DFU bootloader which runs if there’s no firmware. The first time the board is connected it shows up as a DFU device which allows uploading firmware. If the firmware needs to be updated again, the bootloader pins can be shorted to re-run the bootloader (basically, you just short the toes :)) . The PCB edge is also used as a USB connector, so it can be plugged to a USB port directly.
Finally there’s an RGB LED connected to PWMs, no other major parts, some passives and a 3.3v regulator. This sweet device uses the PWM to modulate the RED LED in a breathing or pattern. This is going to be an anniversary to remember!
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