Serial Read string output

[evski]

Firstly, thanks so much for everyone's hard work on cordovarduino! After wasting a lot of time on chrome packaged apps, I found myself here. I now have a working app reading serial data on my android device! However:

I'm using serial read in cordovarduino to write the value of a potentiometer onto a html page. Currently I get 1 character of the string from the Arduino at a time, I'm told this is by design, however I cannot seem to get the output to concat and split in order to give me a complete string.

I've set the arduino to output a '/n' with each value, I'm then concatenating the string using += and looking for /n and splitting into an array and outputting the first item in it. The values from the potentiometer are in the range 0 to 680. So what I see on android is, 6, then 68, then 680 and then it clears and repeats (this is the same with and without the 'split' part of the code). Here's a screen grab showing my tracing of the variables to screen (as in the code below).

I'm running Android 4.4.2 and an Arduino Uno. Apologies in advance if I'm doing something stupid, I'm new to android and javascript and have been trying to get this going for a few days now. Once I get this working I'm planning to pass more data from arduino for buttons, additional pots etc, so being able to simply split the data using a unique identifier, or as parts of an array will be crucial.

Any help very much appreciated! Thanks in advance.

Here is the js code:

//define variables
var serialString = "0";
var view;
var s;
var s2;
var s3;
var i;

//UTF8 to string conversion
function ua2text(ua) {
    s = "";
    for (i = 0; i < ua.length; i++) {

        //convert to string and concat items in array with +=
        s += String.fromCharCode(ua[i]);

        //trace to app for debug
   document.getElementById("logging").innerHTML = "s: " +s;

     //split into array at \n character
s2 = s.split("\n")

 //trace to app for debug
    document.getElementById("logging2").innerHTML = "s2: " +s2;


    //select first item from new array
s3 = s2[0];

 //trace to app for debug
    document.getElementById("logging3").innerHTML = "s3: " +s3;

     }
     //return final output
    return s3;  
}

//device ready event listener
document.addEventListener("deviceready", onDeviceReady, false);
function onDeviceReady() {

    //error callback for serial comms
    var errorCallback = function(message) {
    alert('Error: ' + message);
     document.getElementById('logging').innerHTML = 'Error: ' + message;
};

//serial initialise/open
        serial.requestPermission(
            function(successMessage) {
                serial.open(
                    //set baud rate to match code from Arduino
                    //set dtr to true, as it seems to be mentioned in the FAQ for the driver
                    {baudRate: 9600, dtr: true},
                    function(successMessage) {

                       //Read serial data
                       serial.registerReadCallback(
                           function success(data){

                                //convert array buffer to string
                               view = new Uint8Array(data);

                               //call UTF 8 conversion function and pass it data
                              serialString = ua2text(view)

                            //set graphics variable
                            msg = serialString;

                             //trace to app for debug
    document.getElementById("buffer").innerHTML = "serialString: " +serialString;

                           },
                           function error(){
                               new Error("Failed to register read callback");
                           });
                    },
                    errorCallback
                );
            },
            errorCallback
        );
}

and here is the arduino code feeding it:

int pot1pin = A0;  //pot input 1

void setup() {
  Serial.begin(9600);
}


void loop() {
  delay(100);
    printPotValue();

}


// Output pot value to serial
void printPotValue () {
    int potStatus = analogRead(pot1pin);
    int potStatusVar = potStatus;

    // Print via serial
    Serial.print(potStatusVar);
    Serial.print("\n");

}```

[xseignard]

//device ready event listener
document.addEventListener('deviceready', onDeviceReady, false);
function onDeviceReady() {
    //error callback for serial comms
    var errorCallback = function(message) {
        alert('Error: ' + message);
        document.getElementById('logging').innerHTML = 'Error: ' + message;
    };

    //serial initialise/open
    serial.requestPermission(
        function(successMessage) {
            serial.open(
                //set baud rate to match code from Arduino
                //set dtr to true, as it seems to be mentioned in the FAQ for the driver
                {baudRate: 9600, dtr: true},
                function(successMessage) {
                    //Read serial data
                    serial.registerReadCallback(
                        function success(data){
                            //convert array buffer to string
                            var view = new Uint8Array(data);
                            // get char from the current incoming message
                            var currentChar = String.fromCharCode(view[0]);
                            if (currentChar === '\n') {
                                //trace to app for debug
                                document.getElementById('buffer').innerHTML = 'serialString: ' + serialString;
                                // reset serial string for the next message
                                serialString = '';
                            }
                            else {
                                serialString += currentChar;
                            }
                        },
                        function error(){
                            new Error("Failed to register read callback");
                        }
                    );
                },
                errorCallback
            );
        },
        errorCallback
    );
}

Try something like this (not tested, but the idea is here).

The thing is that registerReadCallback is called each time you receive data (i.e. when you receive the 6 of 680, then when you receive the 8 of 680, and so on).

You need to concatenate the stuff and wait for the \n to come.

Regards,

Xavier

[evski]

Thanks, big improvement. Numbers still jumping though and I can't figure out why. Look at video of app running, show 'serialString' trace here Almost like the code can't keep up or something?

Sent from my iphone using thumbs, please excuse my brevity!

On 13 Aug 2015, at 23:47, Xavier Seignard notifications@github.com wrote:

//device ready event listener
document.addEventListener('deviceready', onDeviceReady, false);
function onDeviceReady() {
//error callback for serial comms
var errorCallback = function(message) {
alert('Error: ' + message);
document.getElementById('logging').innerHTML = 'Error: ' + message;
};

//serial initialise/open
serial.requestPermission(
    function(successMessage) {
        serial.open(
            //set baud rate to match code from Arduino
            //set dtr to true, as it seems to be mentioned in the FAQ for the driver
            {baudRate: 9600, dtr: true},
            function(successMessage) {
                //Read serial data
                serial.registerReadCallback(
                    function success(data){
                        //convert array buffer to string
                        var view = new Uint8Array(data);
                        // get char from the current incoming message
                        var currentChar = String.fromCharCode(ua[0]);
                        if (currentChar === '\n') {
                            //trace to app for debug
                            document.getElementById('buffer').innerHTML = 'serialString: ' + serialString;
                            // reset serial string for the next message
                            serialString = '';
                        }
                        else {
                            serialString += currentChar;
                        }
                    },
                    function error(){
                        new Error("Failed to register read callback");
                    }
                );
            },
            errorCallback
        );
    },
    errorCallback
);

}
Try something like this (not tested, but the idea is here).

The thing is that registerReadCallback is called each time you receive data (i.e. when you receive the 6 of 680, then when you receive the 8 of 680, and so on).

You need to concatenate the stuff and wait for the \n to come.

Regards,

Xavier

—
Reply to this email directly or view it on GitHub.

[evski]

In case you’re interested, changing the delay time in Arduino directly effects the number of characters getting output to serial string. So I’m guessing there’s a bottleneck somewhere. Any ideas welcomed… thanks

On 13 Aug 2015, at 23:47, Xavier Seignard notifications@github.com wrote:

//device ready event listener
document.addEventListener('deviceready', onDeviceReady, false);
function onDeviceReady() {
//error callback for serial comms
var errorCallback = function(message) {
alert('Error: ' + message);
document.getElementById('logging').innerHTML = 'Error: ' + message;
};

//serial initialise/open
serial.requestPermission(
    function(successMessage) {
        serial.open(
            //set baud rate to match code from Arduino
            //set dtr to true, as it seems to be mentioned in the FAQ for the driver
            {baudRate: 9600, dtr: true},
            function(successMessage) {
                //Read serial data
                serial.registerReadCallback(
                    function success(data){
                        //convert array buffer to string
                        var view = new Uint8Array(data);
                        // get char from the current incoming message
                        var currentChar = String.fromCharCode(ua[0]);
                        if (currentChar === '\n') {
                            //trace to app for debug
                            document.getElementById('buffer').innerHTML = 'serialString: ' + serialString;
                            // reset serial string for the next message
                            serialString = '';
                        }
                        else {
                            serialString += currentChar;
                        }
                    },
                    function error(){
                        new Error("Failed to register read callback");
                    }
                );
            },
            errorCallback
        );
    },
    errorCallback
);

}
Try something like this (not tested, but the idea is here).

The thing is that registerReadCallback is called each time you receive data (i.e. when you receive the 6 of 680, then when you receive the 8 of 680, and so on).

You need to concatenate the stuff and wait for the \n to come.

Regards,

Xavier

—
Reply to this email directly or view it on GitHub #35 (comment).

[evski]

Anybody have any suggestions? I'm a bit stuck, sure its simple for a better mind than mine! ;)

[evski]

I've been watching and debugging this further. By slowing down all the comms from the arduino I can see that not all the characters are getting passed consistently from cordovarduino. It seems to miss characters quite randomly. I'm watching the output from 'currentChar'. Any ideas of what might cause this from the plugin side?

[xseignard]

Hello @evski , I finally found time to check all of this, on my side I don't see any problem. Decoding is OK, and it seems there is no missing characters. Here is my code:

Use this as your index.js

var app = {
    initialize: function() {
        document.addEventListener('deviceready', this.onDeviceReady, false);
    },
    onDeviceReady: function() {
        var potText = document.getElementById('pot');
        var delta = document.getElementById('delta');
        var on = document.getElementById('on');
        var off = document.getElementById('off');
        var open = false;
        var str = '';
        var lastRead = new Date();

        var errorCallback = function(message) {
            alert('Error: ' + message);
        };
        // request permission first
        serial.requestPermission(
            // if user grants permission
            function(successMessage) {
                // open serial port
                serial.open(
                    {baudRate: 9600},
                    // if port is succesfuly opened
                    function(successMessage) {
                        open = true;
                        // register the read callback
                        serial.registerReadCallback(
                            function success(data){
                                // decode the received message
                                var view = new Uint8Array(data);
                                if(view.length >= 1) {
                                    for(var i=0; i < view.length; i++) {
                                        // if we received a \n, the message is complete, display it
                                        if(view[i] == 13) {
                                            // check if the read rate correspond to the arduino serial print rate
                                            var now = new Date();
                                            delta.innerText = now - lastRead;
                                            lastRead = now;
                                            // display the message
                                            var value = parseInt(str);
                                            pot.innerText = value;
                                            str = '';
                                        }
                                        // if not, concatenate with the begening of the message
                                        else {
                                            var temp_str = String.fromCharCode(view[i]);
                                            var str_esc = escape(temp_str);
                                            str += unescape(str_esc);
                                        }
                                    }
                                }
                            },
                            // error attaching the callback
                            errorCallback
                        );
                    },
                    // error opening the port
                    errorCallback
                );
            },
            // user does not grant permission
            errorCallback
        );

        on.onclick = function() {
            if (open) serial.write('1');
        };
        off.onclick = function() {
            if (open) serial.write('0');
        }
    }
};

app.initialize();

then this as your index.html

<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *">
        <meta name="format-detection" content="telephone=no">
        <meta name="msapplication-tap-highlight" content="no">
        <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
        <link rel="stylesheet" type="text/css" href="css/index.css">
        <title>Hello World</title>
    </head>
    <body>
        <div class="app">
            <h1>Potentiometer value</h1>
            <p>Value <span id="pot">...</span></p>
            <p id="delta">...</p>
            <button id="on">On</button>
            <button id="off">Off</button>
        </div>
        <script type="text/javascript" src="cordova.js"></script>
        <script type="text/javascript" src="js/index.js"></script>
    </body>
</html>

and this as your arduino code, with a potentiometer on A0 and a led on 13

#define POT A0
#define LED 13

unsigned long previousMillis;
int interval = 50;

void setup() {
    Serial.begin(9600);
    pinMode(POT, INPUT);
    pinMode(LED, OUTPUT);
}

void loop() {
    if (Serial.available() > 0) {
        char i = Serial.read();
        switch (i) {
            case '0':
                digitalWrite(LED, LOW);
                break;
            case '1':
                digitalWrite(LED, HIGH);
                break;
        }
    }
    if (millis() - previousMillis >= interval) {
        previousMillis = millis();
        int value = analogRead(POT);
        Serial.println(value);
    }
}

Please let me know if it works for you.

Regards

[xseignard]

Should be OK with the code above,
I close the issue, feel free to reopen it if you're still stuck