I’m using the code mentioned in the above link for temperature and humidity sensing using the Adafruit feather m0 Lora node with the DHT22 sensor. When I check the payload on TTN it shows inconsistent values for Temperature and Humidity.
Here is the code and payload decoder attached below:
void do_send(osjob_t* j){
// Check if there is not a current TX/RX job running
if (LMIC.opmode & OP_TXRXPEND) {
Serial.println(F(“OP_TXRXPEND, not sending”));
} else {
// read the temperature from the DHT22
float temperature = dht.readTemperature();
Serial.print(“Temperature: “); Serial.print(temperature);
Serial.println(” *C”);
// adjust for the f2sflt16 range (-1 to 1)
temperature = temperature / 100;
// read the humidity from the DHT22
float rHumidity = dht.readHumidity();
Serial.print("%RH ");
Serial.println(rHumidity);
// adjust for the f2sflt16 range (-1 to 1)
rHumidity = rHumidity / 100;
// float -> int
// note: this uses the sflt16 datum (https://github.com/mcci-catena/arduino-lmic#sflt16)
uint16_t payloadTemp = LMIC_f2sflt16(temperature);
// int -> bytes
byte tempLow = lowByte(payloadTemp);
byte tempHigh = highByte(payloadTemp);
// place the bytes into the payload
payload[0] = tempLow;
payload[1] = tempHigh;
// float -> int
uint16_t payloadHumid = LMIC_f2sflt16(rHumidity);
// int -> bytes
byte humidLow = lowByte(payloadHumid);
byte humidHigh = highByte(payloadHumid);
payload[2] = humidLow;
payload[3] = humidHigh;
// prepare upstream data transmission at the next possible time.
// transmit on port 1 (the first parameter); you can use any value from 1 to 223 (others are reserved).
// don't request an ack (the last parameter, if not zero, requests an ack from the network).
// Remember, acks consume a lot of network resources; don't ask for an ack unless you really need it.
LMIC_setTxData2(1, payload, sizeof(payload)-1, 0);
}
// Next TX is scheduled after TX_COMPLETE event.
}
Decoder
function Decoder(bytes, port) {
var temperature = (bytes[0] << 8) | bytes[1];
var humidity = (bytes[2] << 8) | bytes[3];
return {
temperature: temperature / 100,
humidity: humidity / 100
}
}
Dear Sir, Thanks for your kind response. I tried the following decoder copied from your repo. However, it shows the following error attached below in a snapshot.
function sflt162f(rawSflt16)
{
// rawSflt16 is the 2-byte number decoded from wherever;
// it's in range 0..0xFFFF
// bit 15 is the sign bit
// bits 14..11 are the exponent
// bits 10..0 are the the mantissa. Unlike IEEE format,
// the msb is explicit; this means that numbers
// might not be normalized, but makes coding for
// underflow easier.
// As with IEEE format, negative zero is possible, so
// we special-case that in hopes that JavaScript will
// also cooperate.
//
// The result is a number in the open interval (-1.0, 1.0);
//
// throw away high bits for repeatability.
rawSflt16 &= 0xFFFF;
// special case minus zero:
if (rawSflt16 == 0x8000)
return -0.0;
// extract the sign.
var sSign = ((rawSflt16 & 0x8000) != 0) ? -1 : 1;
// extract the exponent
var exp1 = (rawSflt16 >> 11) & 0xF;
// extract the "mantissa" (the fractional part)
var mant1 = (rawSflt16 & 0x7FF) / 2048.0;
// convert back to a floating point number. We hope
// that Math.pow(2, k) is handled efficiently by
// the JS interpreter! If this is time critical code,
// you can replace by a suitable shift and divide.
var f_unscaled = sSign * mant1 * Math.pow(2, exp1 - 15);
return f_unscaled;
}
Hi, no I tried a lot; however, I couldn’t succeed. I am still waiting for @tmm and maybe he could spare a few seconds for our problem. I studied the decoder part mentioned in his GitHub repo, but it was too complex, and I didn’t get it.
Please count me on if you find any solution to this problem.
