I an new from few day in ttn, so be patient with me.
I have a device which send a 2 bytes counter value.
I have the following payload decoder which work when I am testing it :
function Decoder(bytes, port)
{
value = (bytes[0] << 8)|bytes[1];
return {
"value": String(value)
}
}example :
payload = 64 64
result :
{
“value”: “25700”
}
After I use paho.mqtt in ptyhon scipt located on a remote raspberry.
Each time the script receives a upling it crash and says “TypeError: the JSON object must be str, not 'bytes”
Could someone tell me what is happening ?
The problem is on the ttn side or the python side.
all suggestion are welcomed and many thank in advance !!!
#! /usr/bin/env Python3.4
# -*- coding: UTF-8 -*-
import paho.mqtt.client as mqtt
import json
import base64
APPEUI = "ABCDEFABCDEF0000"
APPID = "dynamitron_test"
PSW = 'ttn-account-v2.iNmvcWKseHAcqZ8z5BEBS8PpmZ86ePfBArQchAOppFc'
#Call back functions
# gives connection message
def on_connect(mqttc, mosq, obj,rc):
print("Connected with result code:"+str(rc))
# subscribe for all devices of user
mqttc.subscribe('+/devices/#')
# gives message from device
def on_message(mqttc,obj,msg):
x = json.loads(msg.payload)
device = x["dev_id"]
payload_raw = x["payload_raw"]
payload_plain = base64.b64decode(payload_raw)
datetime = x["metadata"]["time"]
#rssi = x["metadata"]["gateways"]["rssi"] # <== this raises an error (why?)
rssi = -1
print(device + ": " + payload_raw + " ==> " + payload_plain + ", RSSI ["+ str(rssi) + "] @" + datetime )
def on_publish(mosq, obj, mid):
print("mid: " + str(mid))
def on_subscribe(mosq, obj, mid, granted_qos):
print("Subscribed: " + str(mid) + " " + str(granted_qos))
def on_log(mqttc,obj,level,buf):
print("message:" + str(buf))
print("userdata:" + str(obj))
mqttc= mqtt.Client()
# Assign event callbacks
mqttc.on_connect=on_connect
mqttc.on_message=on_message
mqttc.username_pw_set(APPID, PSW)
mqttc.connect("eu.thethings.network",1883,60)
# and listen to server
run = True
while run:
mqttc.loop()