How it works
Write the field map one line per field, NAME hi:lo or NAME bit (NAME[hi:lo] also works), then paste the value you read in the debugger. Each field is extracted as:
field = (value >> lo) & ((1 << (hi − lo + 1)) − 1)
Edit a field’s value or click any bit and the register value updates, so you can build the value to write as well as decode one you read. Overlapping fields and bits outside the register width are flagged.
The default map is STM32 USART_CR1 with the bit layout of the FIFO-capable USART (L4+, G4, H7 and newer): 0x2000800D means USART enabled, receiver and transmitter on, 8× oversampling and FIFO mode. Check the USART chapter of your part’s reference manual before relying on a bit position. The map and value are saved in the URL, so you can share a decoded register.