christian-nils

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• Puck.js IMU data logging

  @christian-nils started

  • 5 comments
  • 1,519 views

  @Gordon replied
• Puck.js IMU data logging

  in Puck.js, Pixl.js and MDBT42 • 3 years, 11 months

  

  Hi again,

  I was able to activate and configure the FIFO buffers directly with JS. Because I do not have much time at the moment, one of my colleagues (much more skilled as well) is currently doing the implementation.

  We are thinking about sharing the code with the community, do you have any requirements for its implementation to maximize its chances to be merged with the upstream repository?

  For now, Puck.accelOnFifo(samplerate) was created and is very similar to Puck.accelOn(samplerate) but uses the FIFO buffer and returns binary data (so it is not converted into a JS object). At the moment, the implementation was done in jswrap_puck.c but you may want it to be done in a separate module?

  EDIT: Sorry, I found the answer to my question https://github.com/espruino/Espruino/blob/master/CONTRIBUTING.md

  /CN

• Puck.js IMU data logging

  in Puck.js, Pixl.js and MDBT42 • 3 years, 11 months

  

  Hi @Gordon, thanks for your quick and comprehensive reply!

  I will give a try to the FIFO buffer!

• Puck.js IMU data logging

  in Puck.js, Pixl.js and MDBT42 • 3 years, 11 months

  

  Hello,

  I would like to log some IMU data using my Puck.js v.2.

  I have set up a SD card reader (w/ SPI HW set to 8Mbps) on it so I can log the data. I can log the data at maximum 160Hz in average which is quite low for what I would like to do. I guess there are a lot of "wasted" time when converting the JSON object to string, and then when writing the data to the file. Note, I am using "Stream File IO".

  I am far from being an expert, but maybe some on this forum could help me to know how much I can expect from the device. If I were to write my own C code to log the data from the IMU directly to the SD card, what would be the possible maximum sampling rate for instance?

  (My messy code below)

  function onInit(){
    // Wire up up MOSI, MISO, SCK and CS pins (along with 3.3v and GND)
  SPI1.setup({mosi:D30, miso:D28, sck:D29, baud: 8000000});
  // console.log(E);
  E.connectSDCard(SPI1, D31 /*CS*/);
  // see what's on the device
    try {
      console.log(require("fs").readdirSync());
    } catch(error){
      console.log(error);
    }
  }
  
  var data = [];
  var i = 0;
  // Store data into filesystem
  function storeMyData(fID, start, a) {  
    if (i>100) {
      i = 0;
      var t = new Date.now();
      fID.write(data);
      console.log((new Date.now()) - t);
      data = [];
    } else {
      data += (Date.now()-start) + "," + 
              a.acc.x + "," +
              a.acc.y + "," +
              a.acc.z + "," +
              a.gyro.x + "," +
              a.gyro.y + "," +
              a.gyro.z + "\n"; 
    } 
    i++;
  }
  
  function openFile(){
    var start = Date.now();
    var fID = E.openFile("data"+start+".csv", "w");
    fID.write("Time (ms), "+
              "acc X, "+
              "acc Y, "+
              "acc Z, "+
              "gyro X, "+
              "gyro Y, "+
              "gyro Z \n");
    return {fID: fID, start: start};
  }
  
  onInit();
  var res = openFile();
  var fID = res.fID;
  const start = res.start;
  
  function onButton(e){
    d = e.time - e.lastTime;
    if (d>0.5) {
      digitalPulse(LED2, 1, [100, 100, 100]);
      Puck.accelOn(208);
      Puck.on('accel', function(a) {
        storeMyData(fID, start, a);      
      });
    } else {    
      try {
        Puck.accelOff();
        fID.close();
        console.log("stopped!");
        digitalPulse(LED1, 1, [100, 100, 100]);
      } catch(error) {
        console.log(error);
      }    
    }
  }
  

  Thanks in advance,

  Greetings