MQTT Client.Publish

Projects Programming
1

Hello,

My C++ coding skills leave a lot to be desired so I apologize in advance.

I am having problems publishing values from my BME280 to my MQTT Mosquitto server.

I can get the print the values to the serial monitor like this:

Serial.print(bme.readTemperature());

But, when I try and do this:

client.publish("WeatherStation1\BME280\Temperature", bme.readTemperature());

I get the error:

no matching function for call to 'PubSubClient::publish(const char [9], float)'

I am pretty sure it's because the "payload" is a "const char[]"

Ideally I have been trying to find a function that I can call that will return the const char without any spaces. So it has calculated the length needed?

Can anyone help me with this conversion please?

2

Can anyone help me with this conversion please?

dtostrf()

3

MQTT commonly uses forward slashes (/) as path delimiters. If you want to use backslashes (), you have to escape them in C++ code:

char buffer[15];
client.publish("WeatherStation1\\BME280\\Temperature", dtostrf(bme.readTemperature(),8,2));