Beaglebone Black串行端口JAVASCRIPT

Question

I am having trouble outputting to an LCD display.

var usblcd = require('./usblcdmo');
var express = require('express');
var app = express();

var fs = require('fs');
var indexhtml = fs.readFileSync('./index.html');

app.get('^/$', function (req, res) {
   res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/clearscreen$/, function(req, res) {
    console.log('clearscreen');
    usblcd.clearscreen();
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/backlight\/(\d)$/, function(req, res) {
    var option = req.params[0];
    console.log('backlight ' + option);
    usblcd.backlight(option);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/blockcursor\/(\d+)$/, function(req, res) {
    var option = req.params[0];
    console.log('blockcursor ' + option);
    usblcd.backlight(option);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/contrast\/(\d+)$/, function(req, res) {
    var option = req.params[0];
    console.log('contrast ' + option);
    usblcd.contrast(option);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/brightness\/(\d+)$/, function(req, res) {
    var option = req.params[0];
    console.log('brightness ' + option);
    usblcd.brightness(option);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/backlightRGB\/(\d+)\/(\d+)\/(\d+)$/, function(req, res) {
    var red = req.params[0];
    var green = req.params[1];
    var blue = req.params[2];
    console.log('backlightRGB ' + red + ' ' + green + ' ' + blue);
    usblcd.backlightRGB(red, green, blue);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get(/^\/show\/(.*)$/, function(req, res) {
    var option = req.params[0];
    console.log('show ' + option);
    usblcd.show(option);
    res.end(indexhtml, {'Content-Type': 'text/html'});
});

app.get('^/quote1$', function(req, res) {
    usblcd.clearscreen();
    usblcd.show('node.js, use the force');
    res.end(indexhtml, {'Content-Type': 'text/html'});
    });

app.get('^/quote2$', function(req, res) {
    usblcd.clearscreen();
    usblcd.show('node.js,  phone home');
    res.end(indexhtml, {'Content-Type': 'text/html'});
    });

app.get('^/quote3$', function(req, res) {
    usblcd.clearscreen();
    usblcd.show('node.js, make my day');
    res.end(indexhtml, {'Content-Type': 'text/html'});
    });

app.get('^/quote4$', function(req, res) {
    usblcd.clearscreen();
    usblcd.show('Houston, we havea node.js');
    res.end(indexhtml, {'Content-Type': 'text/html'});
    });

app.get('^/quote5$', function(req, res) {
    usblcd.clearscreen();
    usblcd.show('node.js, you are our only hope');
    res.end(indexhtml, {'Content-Type': 'text/html'});
    });

app.listen(4000);
console.log('Listening on port 4000');

usblcd.clearscreen();
usblcd.backlight(true);
usblcd.brightness(255);
usblcd.contrast(200);
usblcd.autoscroll(true);
usblcd.backlightRGB(0,255,0);
var now = new Date();
usblcd.show(now.toDateString() + ' ' + now.toTimeString().slice(0, 8));

And this script:

'use strict';

var SerialPort = require("serialport").SerialPort;
var serialPort = new SerialPort("/dev/ttyACM0", { baudrate: 57600 });
var Open = false;
var SaveBuffer = new Buffer(1024);
var SaveLen = 0;

function sp_write(data) {
    if (Open) {
        serialPort.write(data, function(err, results) {
            console.log('err ' + err + ' results ' + results);
        });
    }
    else {
        if (Buffer.isBuffer(data)) {
            data.copy(SaveBuffer, SaveLen);
            SaveLen += data.length;
        }
        else {
            new Buffer(data).copy(SaveBuffer, SaveLen);
            SaveLen += data.length;
        }
        //console.log('SaveLen ' + SaveLen);
    }
}

function show(data) {
    console.log('show ' + data);
    sp_write(data);
}

serialPort.on("open", function() {
    Open = true;
    serialPort.on("data", function (data) {
        console.log('serialPort data');
    });
    serialPort.on("close", function (data) {
        console.log('serialPort close');
    });
    //console.log('SaveBuffer ' + SaveBuffer.slice(0, SaveLen));
    console.log('open, sending buffered data ' + SaveLen);
    serialPort.write(SaveBuffer.slice(0, SaveLen), function(err, results) {
        console.log('err ' + err + ' results ' + results);
    });
    SaveLen = 0;
});

function backlight(data) {
    console.log('backlight ' + data);
    if (data === true || data === 1) {
        sp_write([0xFE, 0x42, 0x00]);
    }
    else {
        sp_write([0xFE, 0x46]);
    }
}

function brightness(bright) {
    console.log('brightness ' + bright);
    sp_write([0xFE, 0x99, bright]);
}

function contrast(contr) {
    console.log('contrast ' + contr);
    sp_write([0xFE, 0x50, contr]);
}

function clearscreen() {
    console.log('clearscreen');
    sp_write([0xFE, 0x58]);
}

function gotoxy(row,col) {
    console.log('gotoxy ' + row + ' ' + col);
    sp_write([0xFE, 0x47, row, col]);
}

function binarychoice(featurename, onCode, offCode, data) {
    console.log(featurename + ' ' + data);
    if (data === true || data === 1) {
        sp_write([0xFE, onCode]);
    }
    else {
        sp_write([0xFE, offCode]);
    }
}

function autoscroll(data) {
    binarychoice('autoscroll', 0x51, 0x52, data);
}

function underlinecursor(data) {
    binarychoice('underlinecursor', 0x4A, 0x4B, data);
}

function blockcursor(data) {
    binarychoice('blockcursor', 0x53, 0x54, data);
}

function backlightRGB(red, green, blue) {
    console.log('backlightRGB ' + red + ' ' + green + ' ' + blue);
    sp_write([0xFE, 0xD0, red, green, blue]);
}

exports.show = show;
exports.backlight = backlight;
exports.brightness = brightness;
exports.contrast = contrast;
exports.clearscreen = clearscreen;
exports.gotoxy = gotoxy;
exports.autoscroll = autoscroll;
exports.underlinecursor = underlinecursor;
exports.blockcursor = blockcursor;
exports.backlightRGB = backlightRGB;

The error is as follows

 Error: Cannot find module 'serialport'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object. (/var/lib/stickshift/52e570dee0b8cdcdb7000005/app-root/data/752908/testlcd/usblcdmo.js:3:18)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)

I am assuming I need a serial port code because it is called upon. I am unsure how to do this. The beaglebone black is a microprocessor that I am attempting to make output to an LCD display.

Answer 1

It seems the module serialport is missing. Try to install it running

npm install serialport

You can also run npm install in your app directory, it will automatically install all dependencies in a folder named node_modules