UART

The uart module lets you talk to a device connected to your board using a serial interface.

Functions

microbit.uart.init(baudrate=9600, bits=8, parity=None, stop=1, pins=None)

Initialize serial communication with the specified parameters on the specified pins. Note that for correct communication, the parameters have to be the same on both communicating devices.

Warning

Initializing the UART will cause the Python console on USB to become unaccessible, as it uses the same hardware. There is currently no way to bring the console back, without restarting the module.

The baudrate defines the speed of communication. Common baud rates include:

  • 9600
  • 14400
  • 19200
  • 28800
  • 38400
  • 57600
  • 115200

The bits defines the size of bytes being transmitted, and the board only supports 8. The parity parameter defines how parity is checked, and it can be None, microbit.uart.ODD or microbit.uart.EVEN. The stop parameter tells the number of stop bits, and has to be 1 for this board.

If no pins are specified, microbit.pin0 is used as the TX pin, and microbit.pin1 as the RX pin. You can also specify which pins you want by passing a tuple of two pins as pins, the first one being TX, and the second one, RX.

Note

When connecting the device, make sure you “cross” the wires – the TX pin on your board needs to be connected with the RX pin on the device, and the RX pin – with the TX pin on the device. Also make sure the ground pins of both devices are connected.

uart.any()

Return True if any characters waiting, else False.

uart.read([nbytes])

Read characters. If nbytes is specified then read at most that many bytes.

uart.readall()

Read as much data as possible.

Return value: a bytes object or None on timeout.

uart.readinto(buf[, nbytes])

Read bytes into the buf. If nbytes is specified then read at most that many bytes. Otherwise, read at most len(buf) bytes.

Return value: number of bytes read and stored into buf or None on timeout.

uart.readline()

Read a line, ending in a newline character.

Return value: the line read or None on timeout. The newline character is included in the returned bytes.

uart.write(buf)

Write the buffer of bytes to the bus.

Return value: number of bytes written or None on timeout.