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Now we will create a publisher for the battery percentage.

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Look at the circuit and we are getting the input at the PIN 36.

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Here it is, the voltage divider that is created by two resistors.

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They are giving us the output which is received in the Esp32 at PIN 36.

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For that, we are going to create a publisher.

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So we will be opening a opening, an example of publisher.

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This is the Microsoft publisher.

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And this topic will also be dependent on.

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Instead we can just work with it.

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We do not need to use more memory, so this is why we are not going to use Int32.

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A large part of you will be using everything same just like that.

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We are going to create a timer and we are also going to create a timer call just like this.

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Let's do this.

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The better win is 36 so we can define it like this.

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We are going to create the object of the publisher that will be publishing the battery.

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And here it is, the object of battery message and the setup.

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We are going to create a timer.

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And the timer will be repeating itself after 100 milliseconds.

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And we also have to add an executor of the timer.

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And because this is the third thread, we are going to change this number to three.

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Here it is the function of timer callback.

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Save it, compile the sketch.

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So so far this is absolutely fine, but this will not give us the value of the battery, so we will

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just have to modify a little bit more.

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And the void setup we will declare the battery pin as an input pin.

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Unlike this, now we are going to create a function that will be iterating the pin and give us the value

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of the percentage of the battery.

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This is the function.

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It should be get battery percentage.

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Here it is the prototype of this.

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And down here we can define that function.

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Here is the function that will be reading the value from the battery pin.

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Here is the map to percentage function.

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We will also create a prototype for this.

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And here, come down here we can define this function.

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Okay, here it is.

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Map to the percentage function that will receive the raw value and set a minimum voltage value and then

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the maximum voltage value and linearize it from 0 to 100, which will give us the percentage.

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And how do we find this value?

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Well, there is a simple mathematical formula as we have potential divider of this value.

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Battery is rated at 3.7V, but actually it gives us four point.

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Voltage at which the esp32 gives us the maximum value for zero nine.

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Five is the maximum it will give us via analog read.

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So we will divide it by 3.30.8 almost and we will multiply it by 4095.

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The Esp32 will give us this value.

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Our battery will be 100% charged.

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Okay, so we have written it here as a rounded of figure and there is also added some safety check.

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This is why this value a little bit higher when the battery is low and it will drop its voltage when

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it reaches three, it will give us 1.9 divided by 313 multiply 4095.

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So this is the value that it will give out at 0% charging.

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Okay.

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Murphy have written a rounded off figure in here.

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Now we have to add the publisher in it.

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We haven't declared it yet.

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And here we will declare the publisher.

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So the publisher is created.

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Now we will just publish percentage value and this timer callback function.

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Now we will plug this in, upload code, upload it successfully.

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Now plug out.

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Open your Microsoft agent.

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Turn on.

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This is the better topic.

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That is good.

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We are seeing the battery percentage.