Both SWD and the serial bootloader can be “locked” by using RDP (Read Protection). On a device this small, with pins around the edge, it is unlikely that SWD will be harder to access than serial. It’s nowhere near as powerful as the SWD interface. It also contains a serial interface on the bootloader than allows us to read and write to the flash memory. This isn’t the only way we can interact with this device though. Last time we looked at using the SWD interface of an STM32 ARM chip.
