Robô controlado por bluetooth

App for cell phone control, via bluetooth, a 4wd robot. It can be any microcontroller. Just have a bluetooth module.
In my example, I used an HC05 module, however any module paired with the cell phone will be accepted.
The application brings a speed slider and also the option to change the direction keys, according to your project.
A pedagogical resource was inserted to choose a letter of the alphabet. Choosing a letter, the robot goes to the position of the letter, picks it up (via an electromagnet), and places the letter in a certain position, and at the end, returns to the initial position.