C - Sparkle Feedback

Let's add some more modules to allow our robot to give feedback about the line it is following.

Add the Line sensor underneath as before then add Sparkle and buzzer modules to your robot like in the picture.

It can be quite hard to see the wiring with so many things plugged in! The motors and line sensor should be the same as before (M1, M2 and P0, P1)

Plug the buzzer into P2, and the Sparkles into P8

Load up your two sensor line follower program from the last lesson.

It should look something like our example in the picture.

Let's use the outer two Sparkles (0 and 2) to show the state of the two infrared sensors.

If the left sensor is on the line (0), turn the left Sparkle green.

If the left sensor is off the line (1), turn the left sparkle red.

Let's change the program so the line follower code isn't used for the moment - we can do this by making it into a function.

Move the line follower code out of the while True: loop and into a function called line_follower that takes no inputs.

Write the code in the picture to test the left sparkle - test it by moving it across the line!

Let's use the right Sparkle (Sparkle 2) to do the same thing for the right hand sensor.

Add some more code to set the right Sparkle in the same way as the left one, but using the right sensor.

There is a hint layout if you need it!

Don't forget to test it properly.

Let's add some more blocks so the middle Sparkle (Sparkle 1) is green when both sensors are on the line.

This is when both left and right are 0!

Add a third IF/ELSE block that checks if both left and right are 0, and sets the middle Sparkle green if they are.

There is a hint layout if you need it.

Don't forget to use and.

You may have thought the last program didn't look quite right - as the robot moved over the line, two Sparkles changed at once!

It would be more sensible for the program to set just the middle Sparkle green when both sensors are on the line, instead of all three.

We need to change the code to do this, to set the colours of all three Sparkles for each combination of sensor states.

In the picture is the structure you will need - a 3 part if, else if, else statement for checking if the robot is to the left, right or on the centre of the line.

Add lines of code to set the sparkles properly!

You may have noticed that our Sparkle code and line following code have some very similar IF blocks.

Move the Sparkle lines into the matching IF statements in the line follower function, to merge your line follower and Sparkle programs together.

Test it properly on the track!

What about when the robot comes off the line completely?

Add some more Sparkle lines to the correct IF statement to turn all the Sparkles red if the robot is off the line.

Our robot should probably make more of a fuss if it gets lost completely and doesn't know where the line is.

Add some code to make the buzzer beep SOS if the robot goes off the line.

You can look back at the Morse Code lesson if you can't remember how to do this!