UART Interface

Note

UART is a Asynchronous serial interface often used as debug console or interfacing with some sensors. It is connected to the ST-Link debugger to allow printf-output to be displayed within the STM32CubeIDE but is also available on the Pmod connectors.

Simple Usage

Reading from and writing to a UART port is as simple as calling the read and write functions of the relevant UART interface.

There’s two versions available: Binary and ASCII transmissions.

If binary data is read or written, the interface reads as many bytes as requested or writes as many bytes as given. It doesn’t stop until everything is done. If ASCII data is read or written, the interface reads until it hits a Line Feed [ \n, 0x0A ] or a Carriage Return [ \r, 0x0D ]. It sends data until it hits a string Null Terminator [ \0, 0x00 ].

CC++

u8 buffer[10] = { 0 };

// Read 10 bytes from the console
yggdrasil_UART_Receive(UARTB, buffer, 10);

CC++

char * txbuffer = "Hello World!\n";

// Send string to console
yggdrasil_UART_Transmit(UARTB, txbuffer, strlen(txbuffer));

u8 buffer[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };

// Send 10 bytes to the console
yggdrasil_UART_Transmit(UARTB, buffer, sizeof(buffer));

Available ports

Name	Bus
ST-Link COM	UARTST / UARTC
PMOD B	USARTA
Raspberry	USARTA & UARTB

Custom UART

In order to control a UART that has not been pre-defined by libyggdrasil, first it needs to be properly configured through the project’s .ioc file. Once this is done, the new UART can be defined like this:

CC++

uart_t MyUART = { &huart2 };

and then used like all the other UART.