From f873251887ee504561e80b33ef23f244d23cb6d4 Mon Sep 17 00:00:00 2001
From: DeflateAwning <11021263+DeflateAwning@users.noreply.github.com>
Date: Thu, 22 Sep 2022 13:25:35 -0600
Subject: [PATCH] Add WioLoRaWANFieldTester decoder

---
 WioLoRaWANFieldTester/decoder.js | 41 ++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 WioLoRaWANFieldTester/decoder.js

diff --git a/WioLoRaWANFieldTester/decoder.js b/WioLoRaWANFieldTester/decoder.js
new file mode 100644
index 0000000..3072361
--- /dev/null
+++ b/WioLoRaWANFieldTester/decoder.js
@@ -0,0 +1,41 @@
+function Decoder(bytes, port) { 
+  // source: https://github.com/disk91/WioLoRaWANFieldTester/blob/master/doc/ConfigureCargo.md#setup-a-decoding-function
+
+  var decoded = {};
+  
+  if ( port != 1 ) return decoded;
+  
+  var lonSign = (bytes[0]>>7) & 0x01 ? -1 : 1;
+  var latSign = (bytes[0]>>6) & 0x01 ? -1 : 1;
+  
+  var encLat = ((bytes[0] & 0x3f)<<17)+
+               (bytes[1]<<9)+
+               (bytes[2]<<1)+
+               (bytes[3]>>7);
+
+  var encLon = ((bytes[3] & 0x7f)<<16)+
+               (bytes[4]<<8)+
+               bytes[5];
+  
+  var hdop = bytes[8]/10;
+  var sats = bytes[9];
+  
+  const maxHdop = 2;
+  const minSats = 5;
+  
+  if ((hdop < maxHdop) && (sats >= minSats)) {
+    // Send only acceptable quality of position to mappers
+    decoded.latitude = latSign * (encLat * 108 + 53) / 10000000;
+    decoded.longitude = lonSign * (encLon * 215 + 107) / 10000000;  
+    decoded.altitude = ((bytes[6]<<8)+bytes[7])-1000;
+    decoded.accuracy = (hdop*5+5)/10
+    decoded.hdop = hdop;
+    decoded.sats = sats;
+  } else {
+    decoded.error = "Need more GPS precision (hdop must be <"+maxHdop+
+      " & sats must be >= "+minSats+") current hdop: "+hdop+" & sats:"+sats;
+  }
+
+  return decoded;
+}
+