UART

The uart module supports communication with computers or devices using serial ports (UART). Use require('uart') to access this module.

Class: UART

An instances of UART represents a UART port.

UART.PARITY_NONE

• <number> = 0.

Do not use a parity bit.

UART.PARITY_ODD

• <number> = 1.

Use odd parity bit

UART.PARITY_EVEN

• <number> = 2.

Use even parity bit

UART.FLOW_NONE

• <number> = 0.

Do not use flow control.

UART.FLOW_RTS

• <number> = 1.

Use RTS flow control.

UART.FLOW_CTS

• <number> = 2.

Use CTS flow control.

UART.FLOW_RTS_CTS

• <number> = 3.

Use both RTS and CTS flow control.

new UART(port[, options])

• port <number> UART port number. This value should be less than max port number.
• options <object> The object of UART options. Default values are depends on board (Check in a board page).
  • baudrate <number> Baud rate. One of the [0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400].
  • bits <number> Number of bits per a character. One of the [8, 9]. Default:8
  • parity <number>. The parity is one of the UART.PARITY_NONE (0), UART.PARITY_ODD (1), or UART.PARITY_EVEN (2). Default: UART.PARITY_NONE.
  • stop <number> Number of stop bits. One of the [1, 2]. Default: 1.
  • flow <number> Flow control. One of the UART.FLOW_NONE (0), UART.FLOW_RTS (1), UART.FLOW_CTS (2), or UART.FLOW_RTS_CTS (3). Default: UART.FLOW_NONE
  • bufferSize <number> The size of internal read buffer.
  • tx <number> UART TX pin number. -1 Not to use this pin. Default: board dependent. Check the Boards document.
  • rx <number> UART RX pin number. -1 Not to use this pin. Default: board dependent. Check the Boards document.
  • cts <number> UART CTS pin number. -1 Not to use this pin. Default:-1
  • rts <number> UART RTS pin number. -1 Not to use this pin. Default:-1

// Create the UART instance and close it
const { UART } = require('uart');
const options = {
  baudrate: 9600,
  bits: 8,
  partity: UART.PARTIY_NONE,
  stop: 1,
  flow: UART.FLOW_NONE,
  bufferSize: 2048,
};
const serial0 = new UART(0, options);
// read or write data...
serial0.close();

write(data[, options])

• data <Uint8Array|string> Data to write.
• options <object>
  • count <number> Indicates how many times to write data. Default: 1.

Writes data to the UART port.

const { UART } = require('uart');
const serial0 = new UART(0, { baudrate: 38400 });

// Write a string
serial0.write('Hello, world\n');

// Write Uint8Array
serial0.write(new Uint8Array([0x00, 0x7f, 0x80, 0xff]));

serial0.close();

close()

Close the UART port.

Event: 'data'

• data <Uint8Array> Received data.

The data event is emitted whenever data is arrived (buffer size may varies).

const { UART } = require('uart');
const serial0 = new UART(0);
serial0.on('data', (data) => {
  var s = String.fromCharCode.apply(null, data);
  print(s);
});