Chirpstack v3 decoder for MKR1310 + DHT22

Devices
1

Hello,
I am having problems configuring my codec decoder for an AM2302 (DHT22) connected to an MKR1310. Much appreciated so far for the help I have received getting the MKR1310 to join the chirpstack gateway (RAK7244).

My IDE monitor shows that the device is correctly sending out the temp and hum.

I have setup the following codec for my device profile but have a problem as I’m not familiar with the format or syntax needed to decode the payload:

Blockquote

function Decode(fPort, bytes) {
var decoded = {};
decoded.temperature = (bytes[0] << 8) | bytes[1] / 100;
decoded.humidity = (bytes[2] << 8) | bytes[3] / 100;
return decoded;
}

Blockquote

I get the following confirmed data on the gateway:

applicationID:“49”
applicationName:“mkr1310”
deviceName:“mkr1310”
devEUI:“3930313052317908”
rxInfo:
frequency:904300000
modulation:“LORA”

bandwidth:125
spreadingFactor:10
codeRate:"4/5"
polarizationInversion:false

adr:true
dr:0
fCnt:665
fPort:0
data:null
humidity:0
temperature:0
tags:

    confirmedUplink:true
    devAddr:"00b6dc9d"
    publishedAt:"2024-10-27T15:55:24.571191170Z"
    deviceProfileID:"4f2437ec-ed99-43e5-8931-614b53d6eb56"
    deviceProfileName:"mkr1310-device"

Blockquote

It gives both temp and hum as “0”
Thanks for any help here. I am not a programmer.
Cheers,
Bob

2

Are you sure your sensor sends data?

What if you manually put some numbers on bytes[] on the sensor?

3

Thanks, clavisound. Not sure where the “bytes” would go which you refer to.
However, the program is running on the IDE serial monitor every couple of minutes and give the following output:

15:33:02.413 -> Temperature:
15:33:02.413 -> 22.90
15:33:02.413 -> Humidity:
15:33:02.413 -> 43.70

My program is this:

//DHT22_MKR_oct26.ino
//=============================
#include <MKRWAN_v2.h>
#include <DHT.h>

LoRaModem modem(Serial1);

String appEui = "0000000000000000"; // Add your own AppEUI here
String appKey = "01020304050607080910111213141516"; // Add your own AppKey here

DHT dht(2, DHT22);

void setup() {
  Serial.begin(115200);
  while (!Serial);
  // change this to your regional band (eg. US915, AS923, ...)
  if (!modem.begin(US915)) {
    Serial.println("Failed to start module");
    while (1) {}
  };
  
  dht.begin();

  int connected = modem.joinOTAA(appEui, appKey);
  if (!connected) {
    Serial.println("Something went wrong; are you indoor? Move near a window and retry");
    while (1) {}
  }
}

void loop() {
  int t = dht.readTemperature() * 100;
  int h = dht.readHumidity() * 100;

  byte payload[4];
  payload[0] = highByte(t);
  payload[1] = lowByte(t);
  payload[2] = highByte(h);
  payload[3] = lowByte(h);

  Serial.println("Temperature: ");
  Serial.println(dht.readTemperature());
  Serial.println("Humidity: ");
  Serial.println(dht.readHumidity());

  modem.beginPacket();
  modem.write(payload, sizeof(payload));
  modem.endPacket(true);
  delay(100000);
}

Does this show that it’s sending data? Maybe it’s just going to the serial monitor but not out to the LoRa payload?
Bob

4

Why fport=0?

The fport for uplink MUST > 0.
You may look at the wrong packet.
Or you send the wrong fport=0.

2 Likes
5

Thanks, but how do I change fport from 0 to a greater value?

6

Before modem.beginPacket add a line

modem.setPort(1);
1 Like
7

That did it! Thank you all and especially clavisound!

1 Like
8

No, @IoTThinks made the nice catch :wink:

Have a nice day.

9

And @clavisound has nice solution.
Glad it works for you.