Add GPS code

testing/GPS-comms.js

@@ -0,0 +1,67 @@
+/* This code allows you to communicate with the GPS
+receiver in Bangle.js in order to set it up.
+
+Protocol spec:
+
+https://cdn.sparkfun.com/assets/0/b/0/f/7/u-blox8-M8_ReceiverDescrProtSpec__UBX-13003221__Public.pdf
+
+*/
+
+Bangle.setGPSPower(1)
+//Bangle.on('GPS',print);
+
+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;
+  }
+  d.push(a,b);
+  Serial1.write(d);
+}
+function UBX_CFG_PMS() {
+  // UBX-CFG-PMS - enable power management - Super-E
+  writeGPScmd([0x06,0x86, // msg class + type
+         8,0,//length
+         0x00,0x03/*1hz*/, 0,0, 0,0, 0,0]);  
+}
+function UBX_CFG_MSG(msg,enable) {
+  //  UBX-CFG-MSG,
+  var types = {
+  DTM:0x0A, // Datum Reference
+  GBQ:0x44, // Poll a standard message (if the current Talker ID is GB)
+  GBS:0x09, // GNSS Satellite Fault Detection
+  GGA:0x00, // Global positioning system fix data
+  GLL:0x01, // Latitude and longitude, with time of position fix and status
+  GLQ:0x43, // Poll a standard message (if the current Talker ID is GL)
+  GNQ:0x42, // Poll a standard message (if the current Talker ID is GN)
+  GNS:0x0D, // GNSS fix data
+  GPQ:0x40, // Poll a standard message (if the current Talker ID is GP)
+  GRS:0x06, // GNSS Range Residuals
+  GSA:0x02, // GNSS DOP and Active Satellites
+  GST:0x07, // GNSS Pseudo Range Error Statistics
+  GSV:0x03, // GNSS Satellites in View
+  RMC:0x04, // Recommended Minimum data
+  TXT:0x41, // Text Transmission
+  VLW:0x0F, // Dual ground/water distance
+  VTG:0x05, // Course over ground and Ground speed
+  ZDA:0x08, // Time and Date 
+  };
+  writeGPScmd([0x06,0x01, // msg class + type
+         3,0,//length
+         0xF0,types[msg],enable?1:0]);  
+}
+
+// Enter super-e low power
+// UBX_CFG_PMS()
+// Disable DTM messages (see UBX_CFG_MSG comments):
+UBX_CFG_MSG("DTM",false);