sending temperature via LoRaWAN

sketch/production.cpp

@@ -60,18 +60,19 @@ static void prepareTxFrame( uint8_t port )
   DS18B20.begin();
   uint8_t cnt = DS18B20.getDS18Count();
   Serial.printf("cnt: %d\n\r", cnt);
-  uint8_t addr[8];
+  const uint8_t SLOT_WIDTH = 8 + 4; // 8 bytes address, 4 bytes value
-  DS18B20.getAddress(addr, 0);
+  appDataSize = cnt * SLOT_WIDTH;
-  Serial.printf("%02x %02x %02x %02x %02x %02x %02x %02x\n\r", addr[0], addr[1], addr[2], addr[3], addr[4], addr[5], addr[6], addr[7]);
+  uint8_t *buf = appData;
-  DS18B20.requestTemperatures();       // send the command to get temperatures
+  for (uint8_t i = 0; i < cnt; i++) {
-  uint32_t tempC = DS18B20.getTemp(addr);
+    uint8_t *addr = (buf + (i * SLOT_WIDTH));
-  Serial.printf("tempC: %08x\n\r", tempC);
+    uint32_t *value = (uint32_t*) (buf + (i * SLOT_WIDTH) + 8);
 
-  appDataSize = 4;
+    DS18B20.getAddress(addr, 0);
-  appData[0] = 0x01;
+    Serial.printf("%02x %02x %02x %02x %02x %02x %02x %02x\n\r", addr[0], addr[1], addr[2], addr[3], addr[4], addr[5], addr[6], addr[7]);
-  appData[1] = 0x02;
+    DS18B20.requestTemperatures();       // send the command to get temperatures
-  appData[2] = 0x03;
+    *value = DS18B20.getTemp(addr);
-  appData[3] = 0x04;
+    Serial.printf("tempC: %08x\n\r", *value);
+  }
 }
 
 RTC_DATA_ATTR bool firstrun = true;

snippets/decoding.txt

@@ -0,0 +1,31 @@
+28EE74AD2E1602F8180A0000
+
+
+>>> from binascii import unhexlify
+>>> unhexlify('0001')
+b'\x00\x01'
+>>> from struct import unpack
+>>> unpack('<I', unhexlify('0001'))
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+struct.error: unpack requires a buffer of 4 bytes
+>>> unpack('<I', unhexlify('00000001'))
+(16777216,)
+>>> unpack('<I', unhexlify('180A0000'))
+(2584,)
+>>> unpack('I', unhexlify('180A0000'))
+(2584,)
+>>> unpack('>I', unhexlify('180A0000'))
+(403308544,)
+>>> 0xa28
+2600
+>>> 0xa18
+2584
+>>> unpack('<I', unhexlify('180A0000'))
+(2584,)
+>>> a='28EE74AD2E1602F8180A0000'
+>>> a[0:15]
+'28EE74AD2E1602F'
+>>> a[16:]
+'180A0000'
+>>>