#serialport

[diygeeksindia-blog]

Serial Port programming using Visual Basic for Embedded Developers.Learn how to interface your microcontroller with PC using Visual Basic .net

[nurawal]

permasalahan dengan usb serial port yang hanya bisa dipakai oleh satu aplikasi

[skitsanoscom]

Reading MHZ-19 sensor data in Node.js

Below is an example on how to read CO2 level readings from MHZ-19 NDIR sensor via serial port in Node.js

/** * MHZ-19 UART Monitor * @author skitsanos */ const winston = require('winston'); const Transport = require('winston-transport'); const fs = require('fs'); const SerialPort = require('serialport'); const port = new SerialPort('/dev/tty.usbserial', {baudRate: 9600, autoOpen: false}); class FileTransport extends Transport { constructor(opts) { super(opts); } log(info, callback) { fs.appendFile(process.cwd() + '/app.log', `${info.level} ${info.message}\n`, (err) => { if (err) { console.log(err.message); } }); callback(); } } const loggingFormat = winston.format.combine( winston.format.colorize(), winston.format.splat(), winston.format.printf(info => { return ` ${(new Date()).getTime()} ${info.level}: ${info.message}`; })); const log = winston.createLogger({ exitOnError: false, //level: 'debug', transports: [ new FileTransport( { format: loggingFormat, timestamp: true } ), new winston.transports.Console({ format: loggingFormat }) ] }); let app = { meta: require('./package'), commands: { READ_VALUE: Buffer.from([0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79]) }, utils: { ord: (str) => { console.log(str); return str.charCodeAt(0); }, sleep: (ms) => new Promise(resolve => setTimeout(resolve, ms)) }, serial: { list: () => { SerialPort.list().then((arr_portInfo) => { arr_portInfo.map(el => { console.log(el); log.info('Found: ' + el.comName); }); }); }, open: () => { if (port !== undefined) { return new Promise((resolve, reject) => { port.open(err => { if (err) { return reject(err); } return resolve(); }); }); } else { log.error('Failed to open port. Not found?'); } }, close: () => { if (port !== undefined) { log.debug('Closing serial port'); port.close(); } else { log.error('Failed to open port. Not found?'); } }, write: (data) => { return new Promise((resolve, reject) => { if (port !== undefined) { log.debug('Writing to serial port...'); port.write(data, (err) => { if (err) { return reject(err); } return resolve(); }); } else { return reject({message: 'Failed to write. Not found?'}); } }); } } }; log.info(`${app.meta.name} ver. ${app.meta.version}`); app.serial.open().then(() => { log.debug('Port open'); port.on('readable', async () => { const buf = port.read(9); if (buf !== null && Buffer.byteLength(buf) === 9) { if (buf[0] === 0xff && buf[1] === 0x86) { const co2 = Number(buf[2].toString()) * 256 + Number(buf[3].toString()); log.info(`${co2}ppm`); } await app.utils.sleep(5000); app.serial.write(app.commands.READ_VALUE); } }); app.serial.write(app.commands.READ_VALUE).then(() => { }).catch(err => log.error(err.message)); }).catch(err => log.error(err.message));

[tuangstudio]

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#BTS เทพน้องโม #dmapsgworkshop2017 🍉 #p5js #arduino #video #serialport #connection

[lalitnandandiwakar]

Home Automation using IoT #nirmana #nirmana_2k16 #SISTec_Team #SISTec_Students #SISTec_CSE #SISTer_ECE #college #me #offerlocation #internetofthings #iot #raspberrypi #mobile #msp430 #msp430g2553 #linux #opensource #router #led #wifi #web #charger #wire #internet #serialport (at Sagar Group of Institutions (SISTec))

[betacontroller]

Phase 2.1: Talking Sense over Serial

Following a series of copy-paste hacks scraped from various websites and forums, I was left frustrated and confused. Everything seemed to be set up properly, from baud rate through Node.js buffer code through the wiring.. yet I was still receiving nonsense messages into my audio interface.

After several days and rewrites, I was on the verge of giving up.. which is when most excellent breakthroughs happen. Here are the steps I took to effectively communicate Midi messages over the UART serial on the Raspberry Pi. 

This is a revised workflow from my previous post regarding Raspberry Pi setup, but has an important addition that made all the difference.

First, I edited /boot/cmdline.txt on the Pi:

sudo nano /boot/cmdline.txt

replace contents with:

dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 bcm2708.uart_clock=3000000 elevator=deadline rootwait

This enables the AMA0 serial port on the Pi to be used by Node. The important change here vs. my previous attempt is initializing the uart_clock to 3000000. I honestly have no idea what this is for, but thanks to this guy and his writeup for giving me something to try!

Second, I added some lines to the end of /boot/config.txt :

sudo nano /boot/config.txt

Add lines to end: 

# change uart clock to 2441406 for midi 31250 baud rate init_uart_clock=2441406 init_uart_baud=38400

This slows down the Pi serial baud rate to approximately 31250 if a serialport is opened at 38400 baud rate (one of the standard baud rates supported). Note that only after initializing the UART clock, this was successful.

Third, I modified write access to the AMA0 port to allow Node.js to use it

chown pi /dev/ttyAMA0

chmod a+rw /dev/ttyAMA0

Next up, talking midi with Node.js!

[betacontroller]

Phase 2: Talking Nonsense over Serial

This has been an involved process, and I still have not solved the core of the problem, but I've learned some stuff. Here goes.

I've set up a tiny Node.js app to test Midi output via a web interface. The front-end is a few buttons that send socket messages via Socket.io to the Node app.

Upon receiving these socket messages, the Node app will ideally translate the intended result as defined in client-side code to meaningful Midi messages out over serial.

Here are the issues I've run into:

I can get midi messages sent out from the Pi, but the messages received and logged by my MOTU audio interface are NOT what I intend. 

I do not understand binary code, or converting binary, hex, and decimal numbers in a really meaningful way. I can definitely hack things together, but hacking with intent is the next big step.

I do not understand the low-level C++ code used in the Node serialport module enough to tell if the protocols being used are correct.

The process I'm using encodes a NoteOn message into the values specified by the Midi standard. For a Note On event, there are 3 bytes sent. The first byte specifies the command (note on) and the channel # (1-16), the second byte specifies the pitch (0-127) and the third byte specifies velocity (again 0-127).

I am writing these three values into a Node buffer and writing them out over serial. 

What I see in Midi Ox (on my PC, screen cap below) are three separate midi messages, none of which is a note on, and all of which have the wrong channel number. 

There is obviously some extra data getting inserted somewhere between Node and the serial port, I will continue to investigate.

[betacontroller]

Phase 1: Configure the Pi for Midi

I chose the Raspberry Pi as my primary communication mechanism for a couple reasons. First, I am already familiar with the device having used it on a couple hack projects this year. 

Second, after attempting to use the Pi with an Arduino to relay web events over serial and output Midi messages from the Arduino, I discovered a translation issue with differing baud rates between the devices. At this point, I chose to pair down my attempts and use only the Raspberry Pi.

Setting up the Pi to send midi messages is a little involved, but not over complicated. I referenced an excellent post by Silicon Stuff to hack the serial baud rate close to 31250 (Midi spec).

First, I hooked the Midi cable up to the Pi. 

Pin 1 (5v) goes through a 220 ohm resistor to Pin 5 of the Midi cable.

Pin 5 (Ground) goes to the ground Pin 2 of the Midi cable.

Pin 7 (TX - serial transmit) goes to Pin 4 of the Midi cable.

Second, I edited /boot/cmdline.txt on the Pi:

sudo nano /boot/cmdline.txt

replace contents with:

dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

This enables the AMA0 serial port on the Pi to be used by Node.

Third, I added some lines to the end of /boot/config.txt :

sudo nano /boot/config.txt

Add lines to end: 

# change uart clock to 2441406 for midi 31250 baud rate init_uart_clock=2441406 init_uart_baud=38400

This slows down the Pi serial baud rate to approximately 31250 if a serialport is opened at 38400 baud rate (one of the standard baud rates supported).

Fourth, I modified write access to the AMA0 port to allow Node.js to use it

chown pi /dev/ttyAMA0

chmod a+rw /dev/ttyAMA0

Now, the Pi is able to communicate at the speed that Midi requires.