Firmata - Multiple SoftwareSerial

[brunicius]

Hey, guys,

I'm trying to communicate serial devices (pins rx / tx) on the arduino with StandardFirmataPlus, in NodeJS using the "firmata" module, do the following:

var firmata = require("firmata");

var board = new firmata('/dev/ttyUSB0');

board.on("ready", function () {

console.log('Board is ready');

var SerialPort = board.SERIAL_PORT_IDs.DEFAULT;

board.serialConfig({
portId: SPort,
baud: 115200,
rxPin: 50,
txPin: 52
});

board.serialRead(SPort, 1024, function(data) {

if (data) {
console.log(new Buffer.from(data).toString("ascii"));
board.serialWrite(SPort, new Buffer.from('Hello', 'ascii'));
}

});

});

I saw that I need to use a serial port ID, would this be for communication with the host computer?

But what I really want to know is: how can I connect more than one SoftwareSerial device like that?

[brunicius]

I'm using the serial for YS-IRTM infrared module.

[dtex]

Arduino Uno?

serialPort is unused and SPort is undefined. Are these supposed to be the same?

[brunicius]

Sorry I forgot to get the updated code,

here it is:

var firmata = require("firmata");

var board = new firmata('/dev/ttyUSB0'); //My Arduino Mega 2560 on /dev/ttyUSB0

board.on("ready", function () {
console.log('Board is ready');

var SerialPort = board.SERIAL_PORT_IDs.DEFAULT;

board.serialConfig({
portId: SerialPort,
baud: 115200,
rxPin: 50,
txPin: 52
});

board.serialRead(SerialPort, 1024, function(data) {
if (data) {
console.log(new Buffer.from(data).toString("ascii"));
board.serialWrite(SerialPort, new Buffer.from('Hello', 'ascii'));
}
});

});

[dtex]

Oh wait, you're on a Mega right?

[dtex]

On a mega I would try to use one of the hardware serial ports. Software serial is not reliable at 115,200. You wouldn't want to go over 57,600.

[dtex]

Here's the code updated to use hardware serial. Looking at this I can see that hardware serial 1 is attached to pins 18(TX) and 19(RX). You don't have to specify them.

const firmata = require("firmata");
const board = new firmata('/dev/ttyUSB0');
const SerialPort = board.SERIAL_PORT_IDs.HW_SERIAL1;

board.on("ready", () => {
  console.log('Board is ready');
  
  board.serialConfig({
    portId: SerialPort,
    baud: 115200
  });

  board.serialRead(SerialPort, 1024, (data) => {
    if (data) {
      console.log(new Buffer.from(data).toString("ascii"));
      board.serialWrite(SerialPort, new Buffer.from('Hello', 'ascii'));
    }
  });
});

[brunicius]

Yeah man, it works. But how i do it with others pins, just declare in serialConfig() options?

[brunicius]

Can i use another pins?

[dtex]

Yes, but...

You can use any GPIO pin, but only with software serial. Software serial is limited to 57,600 baud max. Can the device you are talking to be configured to use <=57,600? If not then you'll need to use one of the hardware pin combinations (14 & 15, 16 & 17, or 18 & 19).

[brunicius]

The infrared module works at 9600 baud rate. No problem, right?

[brunicius]

That's the module.

[dtex]

Right, 9600 should be fine. I've used software serial @ 9600 baud with GPS breakouts no problem.

const firmata = require("firmata");
const board = new firmata('/dev/ttyUSB0');
const serialPort = board.SERIAL_PORT_IDs.SW_SERIAL0;

board.on("ready", () => {
  console.log('Board is ready');
  
  board.serialConfig({
    baud: 9600,
    rxPin: 50,
    txPin: 52
  });

  board.serialRead(SerialPort, 1024, (data) => {
    if (data) {
      console.log(new Buffer.from(data).toString("ascii"));
      board.serialWrite(SerialPort, new Buffer.from('Hello', 'ascii'));
    }
  });
});

[dtex]

According to this spec sheet, 9600 is the default speed.