Differential signals

[bryan78]

It would be nice to have a feature to output a differential signal to replicate rs485.  I find myself often having to generate a pattern on one pin and then the inverse on another to drive a differential signal.   It would also be nice if this was available under protocols.

[attila]

Hi @bryan78

It can be done using DIOs 0/3.3V, just select for both Idle 0. Here I used idle 1 for A to be able to decode it as nondifferential.
Also see the 2nd method using Wavegen up to +/-5V

const tx = "hello";
const hz = 9600;
var rga = [], rgb = [];
for(var i = 0; i < tx.length; i++){
    rga.push(0); rgb.push(1); // start
    for(var j = 0; j < 8; j++){
        var c = 1&(tx.charCodeAt(i)>>j);
        rga.push(c); rgb.push(1-c);
    }
    rga.push(1); rgb.push(0); // stop
}
Patterns.Channels.DIO0.custom = rga;
Patterns.Channels.DIO1.custom = rgb;
Patterns.Channels.DIO0.Frequency.value = hz;
Patterns.Channels.DIO1.Frequency.value = hz;
Patterns.States.Run.value = 10.0*i/hz;
Patterns.States.Repeat.value = 1;
Patterns.run();

const tx = "hello";
const hz = 9600;
var rga = [], rgb = [];
for(var i = 0; i < tx.length; i++){
    rga.push(-1); rgb.push(1); // start
    for(var j = 0; j < 8; j++){
        var c = 1&(tx.charCodeAt(i)>>j);
        rga.push(c?1:-1); rgb.push(c?-1:1);
    }
    rga.push(1); rgb.push(-1); // stop
}
Wavegen.Custom.set("A", rga);
Wavegen.Custom.set("B", rgb);
Wavegen.Channel1.Custom.SampleRate.value = hz;
Wavegen.Channel2.Custom.SampleRate.value = hz;
Wavegen.States.Run.value = 10.0*i/hz;
Wavegen.States.Repeat.value = 1;
Wavegen.run();

 

[nurber3]

Hi All.  I wonder if relevant Workspace can be included in posts like this.  I get the sense of what is happening here and can certainly copy and paste the script given the posted script text, but I'm having difficulty duplicating the Wavegen configuration and as a beginner feel like I can save a bunch of time and learn more if there was a workspace ?

Thank you,  Sven  

[nurber3]

Didn't realize that scripts will populate much of the Wavegen config.  Initially I tried creating the Wavegen configuration details before executing the script and did something that prevented it from working, but just tried again doing much less and it worked.  Sorry for noise.