Raspberry Pi Robot

This repository is dedicated to documenting the robot I made using microPython and Raspberry Pi.

You can see it in action here.

Here I will go over:

• the components I use
• some values I set in the code
• the code's general structure
• how I communicate with it

The Components

The noteworthy components I use are:

• a Raspberry Pi Pico H
• HC-05 Bluetooth module
• a simple piezo-buzzer
• 2 SG 90 servos (microservos, as not to bother with powering them up)

Set Values in the Code

They are as follows

• The PWM frequency for the microservos is 50 Hz.
• The Baud Rate for the Bluetooth chip is set to 9600, as per standard..Despite the commands being really basic, I didn't bother setting it any lower. 9600 is on the lower end of UART transmission anyway.
• The Buzzer frequency for when it's active is set to 1000 Hz.
• The 2 positions that the servos move between in the old.py script (1000 and 6000 respectively) are chosen at random. I could potentially set a wider angle so the arm has a larger range of mobility.
• The STEP variable is to determine how fast the servo schanges position. The higher it is the faster the servo will move. I set it to 50 for smooth movement. It also runs a lower risk of the robot losing balance, with the base being 0.5 kg.

The structure of the code

main.py

After initializing the starting position for each servo I snap both servos to it. After this, based on the command read, I either decrement or increment one of the positions.I attached a piezo buzzer so I have an indicator for when the command has been received succesfully.The bluetooth module may lose connection at random.

old.py

The first itteration of the script but instead of allowing for "precise" movement between 2 points for each servo, it moves the arm to one of four positions.The commands are simple so I ended up mapping them to a dictionary.

Communication

I send the robot commands via the Bluetooth module, thus I need a bluetooth-compadible device. For this project I used a phone with the "Serial Bluetooth Terminal" app. It also allowed me to set the commands for the servos as macros. Highly recommend it.

Implementaton in C

I adeed the implementation in C of this script along with a makefile to install the dependencies needed. Simply run make install-deps and make in the src directory. The program is to be compiled with gcc main.c -lwiringPi -o main.