chuckm / bb_usart

STM32F4DISC-BB Uart example to use the on board USART for a console.

README

This example program sets up USART6 on the STMF32F4DISC-BB base board for use as a console port. Note it is designed to work with the existing libopencm3 build setup. Normally it would live in libopencm3-examples/examples/stm32/f4/stm32f4-discovery/bb_usart

Some things to note before this will work.

The pins in the DB9 shell connect to a level shifter on the board but that level shifter is not connected to the actual UART pins (PC6, and PC7) unless you install jumpers on the end of connector for (labelled CON4 on the base board).

The DB9 connector is a 'male' connector, so you cannot use a regular PC cable to connect it to your PC, instead you can either connect a NULL modem cable between the board and your PC, or you can wire the pins on CON4 from 1->4 and from 2->3 (which crosses over transmit and recieve) and put a 'gender changer' on the DB9 and connect a regular cable. In all cases the only signals that are used are receive, transmit and ground so you have to be sure your terminal program is ignoring hardware flow control.

The terminal settings for the receiving device/PC are 115,200 8n1 by default if you call 'setup_bb()' with a different baudrate that works fine as well. If you are using the BlackMagic Debugger then either set the baudrate below 38,400 or make sure you have the 'high baudrate' version of the firmware.