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  • Here's my test bed code (based on your test code). I just load it into the IDE and test via the command line. Hoping some of the PM2 functions does the trick, though I can see lots of questions on the web on how to get this to work. I am switching evenings between writing bits of code and reading the datasheet and doing a test session on another day.

    test bed for working out lowest power consumption, with workable GPS
    Load into IDE and upload code to RAM when connected to watch
    Bangle.on('GPS-raw',function (d) {
      if (d[0]=="$") return;
      if (d.startsWith("\xB5\x62\x05\x01")) print("GPS ACK");
      else if (d.startsWith("\xB5\x62\x05\x00")) print("GPS NACK");
      // 181,98 sync chars  
      else print("GPS",E.toUint8Array(d).join(","))­;
    function writeGPScmd(cmd) {
      var d = [0xB5,0x62]; // sync chars
      d = d.concat(cmd);
      var a=0,b=0;
      for (var i=2;i<d.length;i++) {
        a += d[i];
        b += a;
    // quick hack
    function wait(ms){
      var start = new Date().getTime();
      var end = start;
      while(end < start + ms) {
        end = new Date().getTime();
    function UBX_CFG_PMS() {
      // UBX-CFG-PMS - enable power management - Super-E
      writeGPScmd([0x06,0x86, // msg class + type
             0x00,0x03, 0,0, 0,0, 0,0]);  
    function UBX_CFG_INTERVAL(period, ontime) {
      writeGPScmd([0x06,0x86, // msg class + type
             8,0, //length
             //v0,  interval     period             ontime           reserved
             0x00,  0x02,        period,        0,  ontime,     0,    0,      0  ]);
             // the values are little endian, least significant byte first
     * set update baud rate
     * the setting is in milliseconds in 2 bytes, max 65 seconds
     * we are passing in a value in seconds
     * we set the most significant byte only
     * 8 seconds ~ 8192ms 0x2000, 0x20 = 32 = 4*8
    function UBX_CFG_RATE(rate) {
      rate = (rate * 4) % 256;
      console.log("rate=" + rate);
      writeGPScmd([0x06,0x08,  // class, id 
    	       0x06, 0,          // length
    	       0x00, rate,       // b0: 8192ms 0x2000,  0x00FF (~65sec)
    	       0x01, 0x00,       // b2: 
    	       0x01, 0x00]);     // b4: timeref GPS
     * Save configuration otherwise it will reset when the GPS wakes up
    function UBX_CFG_SAVE() {
      writeGPScmd([0x06, 0x09,   // class id
    	       0x0D, 0x00,   // length
    	       0x00, 0x00, 0x00, 0x00,  // clear mask
    	       0xFF, 0xFF, 0x00, 0x00,  // save mask
    	       0x00, 0x00, 0x00, 0x00,  // load mask
    	       0x01]);                  // b2=eeprom b1=flash b0=bat backed ram
                                            // code on github had 7 - all 3 set ?
    function onGPS(fix) {

    I am hoping if you can test connected to a milliamp meter on the bench you might be able to find the right sequence to get to the magic 2mA current usage. I am looking for a usable fix update between 30-60 seconds. This is why I have set UBX_CFG_PM2 to 30 and 20 seconds for the update and search times (though as I say, yet to try these new functions, I have just drafted them out tonight).


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