This piece of code gets the value from the slider and stores it in a LOCAL variable called value.
Because it’s a local variable, you can’t use it anywhere else in your code. So, you need to change this to a GLOBAL variable by declaring it at the top of your code, where you declare your other variables such as ssid, pass etc.
I’d also recommend that you give it a more appropriate name, maybe humidty_setpoint.
Once you’ve done this your BLYNK_WRITE(V1) will look like this:
BLYNK_WRITE(V1)
{
humidty_setpoint = param.asInt();
}
Then, in your sendSensor() function (which also ought to have a more appropriate name), you then need to do a comparison between the humidity reading that you’ve just taken and the humidty_setpoint value using an 'if` statement.
Your logic may then be that if the humidity is higher than the humidty_setpoint then turn our LED on, else turn your LED off.
I’ll let you translate that into actual code, otherwise you wont learn anything.
Also, don’t use an analogWrite command to turn the LED on/off, use a digitalWrite command instead.
If your LED is active HIGH (on when a HIGH signal is applied) then digitalWrite(14, HIGH) will turn it on, and LOW will turn it off. But, the ,logic may be reversed, you’ll need to check.
The other thing you’ll need is a Blynk.syncVirtual(V1) command in a BLYNK_CONNECTED function, to get the value from the slider at start-up.
More info on that here:
In real-world control systems like this, you’d obviously normally monitor the temperature rather than the humidity, and put the heating on if the temperature is below the set point, and turn it off if it’s above the set point.
With real systems what you want to avoid is the heating constantly turning on an off as the temperature hovers around the set point. You achieve this by building-in some “insensitivity” to the system, by waiting until the temperature is slightly below the set point before turning the heating on, and not turning the heating off again until the temperature is slightly above the set point. This is known as Hysteresis.
More info here…
Pete.