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Hey, now we're going to add the last topic in the code and our report will be ready.

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And this topic is on which we will be publishing velocity and report will be we are going to utilize

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this code and make some changes in our code.

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It is important to twist message.

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So we will be copying this and paste it here.

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This is the first step and then then it is adding the objects of subscriber and the messages.

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And in here there is a callback function that it is calling and here it is, the Micro-roasters subscriber.

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Here are the objects of the subscriber and the message.

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And now we are going to add the subscriber.

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Here it is, the subscriber with the topic.

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And under here we are going to add a new thread and here we will just write it for because this is a

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new thread and here it is, the callback function that we are going to define up here.

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And this is the callback function in which we are just getting the value of the linear x and, and the

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we are getting the value of angular C and we are assigning it to the angular and then we are calculating

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the motor speed and the motor speed is the linear minus angular over two multiply by 2000.

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This is not the actual formula to calculate the speed of the motor, but for the sake of simplicity,

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we are using this formula so that we can move our robot at the basic level.

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Now we have to move our fields as well.

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We have connected our fields on PIN 25, 26 and 27 and 14, and here are the pins.

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If we give some value to the PIN 14, then the left motor will be moving forward.

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And if we give some value to the 27 pin, it will be moving backward, the left motor and for the right

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motor these two pins are choosing.

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Now we have to set the mode of these pins to the output mode and the void setup.

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Now we will again go to the callback function and we also have to initialize these motor speed variables

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and we will be initializing it here and come back to the callback function callback.

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And in here we are going to use some flex and heresy logic for motor speed.

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Left is greater than zero.

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Then the left motor is going to move and here we are playing with the number 4010.

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What does it do?

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The value on which the words is from 0 to 255.

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But if we give a value of ten, the motor does not move because the motor has the internal resistance.

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There is also some weight of the robot.

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So this is why the motor does not move.

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So if we give 40 value to the pen, then it starts to move very slowly.

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Then we can increase and the speed will be gradually increased with this, with the higher value of

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petroleum.

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Now we have to assign these speed value to the particular fields of the robot.

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For that, we are going to create a function.

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And in here, here it is the function set motor and it takes the left speed and speed, right.

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If the speed left is greater than zero, then it is going to set the end to pin to low.

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Because if the this pin is high, then the left motor will be moving backward.

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So if this is low, then it's fine.

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It is not going to move anywhere and then it assigns the value to the end pin.

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Fun in pin one will be driving left wheel.

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There is also a limit to the pin it the maximum it can go as to 50 because if we give the higher speed

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of the value to the motor driver, the motor cross a lot of current and in some cases it it turns off

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the esp32.

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So this is like a precaution.

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You can play with your robot and you can also find out what value suits your robot.

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If the left speed is less than zero, then it is setting the in one pin low and then giving the value

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to the into.

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The same is the case with the speed.

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Right.

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Okay.

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And this condition checks.

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If the boats speeds are zero, then it's going to set all the pins to low.

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Okay.

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So this is the function that we are going to call in here.

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And we will also have to define the prototype.

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So these are the function prototypes.

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And now we are going to upload the code.

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So now plug the esp32 in upload so the upload is successful.

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Now plug out the esp32 and turn on the robot connected via microprocessor.

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So go to your robot workspace and solve it first.

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And there you are connecting.

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So we will give it a restart.

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This is connected now.

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So there we go.

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There is the topic.

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Now we are going to publish our.

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And now press I and support is moving.

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The value is a little bit higher, so I will decrease it via pressing the Z.

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There you go.

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It is working now.