/Magma_Mini_Bot

Mini bot arduino example code

Primary LanguageC++

Magma_Mini_Bot

This document: https://github.com/dkaulukukui/Magma_Mini_Bot/blob/master/README.md

INTROUDUCTION:

This code is to support the Kalani Highschools MAGMA Robotics pre-FIRST season's Mini-bot project. The goal of this project is to familiarize students with the skills and thought processes needed to succeed during this years FIRST robotics season. Kalani HS will be building 6 "Mini-bots" which will compete in a number of mini-competitions.

In order to keep costs per bot down it was decided to go with an Arduino based robot using Mobile phone based Bluetooth controllers.

Bill of Materials:

Step by Step Instructions:

Arduino Setup Instructions:

  1. Download Arduino IDE https://www.arduino.cc/en/Main/Software
  2. Install
  3. Test Arduino Installation and board by loading the test sketch “Blink”
  4. Open Arduino.exe
  5. Open example sketch Blink Go to File>Examples>01.Basics> “Blink”
  6. Set your board type to UNO
    • Tools>Board>”Arduino/Genuino UNO”
  7. Set your COMM port
    • Tools>Port> “This value will vary depending on what USB port you are plugged into. It should be something like “COM4 (Arduino/Genuino)”.
  8. Upload sketch to arduino
    • Click upload button at top or Sketch>Upload
  9. Sketch should upload successfully to arduino and onboard led should start blinking.
  10. Bonus: Try modifying the delay values on lines 34 and 36 then re-uploading the sketch.
  11. Side note: I prefer the IDE to show line numbers to make debugging easier. To enable this go to File>preferences and check the box that says “Display Line Numbers”

Testing the Bluefruit BLE shield

  1. The bluetooth shield will need to have some headers soldered on to put onto the arduino. Follow the soldering assembly instructions here: https://learn.adafruit.com/adafruit-bluefruit-le-shield/assembly
  2. Once complete then install the shield onto the arduino board. Be careful to not bend the pins as you do so.
  3. Download and install the Adafruit IOS/Android app onto your the mobile device of your preference. Search for “Adafruit Bluefruit LE Connect” in the app store of your choice, install.
  4. We will need to install some additional libraries before we are ready to test.
    • Sketch>Include Library>Manage Libraries
    • Search for “Adafruit BluefruitLE nRF51”
    • Click on install in the bottom right corner of the result.
  5. Load the controller test sketch to the Arduino
    • File>examples>Adafruit BluefruitLE nRF51>controller (this will be all the way at the bottom, you may need to hover over the arrow at the bottom of the menu to see)
    • Upload Sketch to arduino
  6. Once the sketch is successfully uploaded then open the serial monitor feature of the arduino IDE.
    • Tools>Serial Monitor
    • Change the baud rate from 9600 to 115200. There is a drop down box in the lower right corner of the screen to do so. You should see some text appearing which starts with ” Adafruit Bluefruit App Controller Example”
  7. Open up the Adafruit BluefruitLE app on your mobile device and connect to the arduino
    • Note: Ensure that bluetooth is enable on your device *You should see a device listed at the bottom that says “Adafruit Bluefruit LE”, click on the connect button to connect.
    • The device should now be connected and be showing you signal strength in dBM and a list of modules. We are going to select the controller module. Click on the controller module.
    • On the next screen will display a number of data streams to turn on, these would allow you to control the device using motion data from your mobile device, we are not going to use those for now. Click on the control pad option at the bottom. You should now see an array of direction arrows and 4 buttons.
    • Start mashing buttons and take a look at the serial monitor on your computer. You should see some text indicators showing each time a button is pressed and release.
    • Note the button numbers associated with the direction buttons, we will need these later.
  8. Play around with some of the other features available.
    • Turn on Gyro then look at the serial display as you move your phone around.
    • Do the same for the accelerometer

Testing Code from this Git Repo

  1. Download this repo as a ZIP file
    • Green button at the top right of this page "Clone or Download"
  2. Extract the entire folder to your desktop or location of your choice
  3. Open up folder
  4. Double click on "Magma_Mini_Bot-master.ino"
  5. Arduino IDE should open up Sketch with all required files present
  6. Compile program to make sure there are no issues.
  7. Load program onto your Arduino/BLE shield board
  8. Open the serial monitor as you did before to 115200 baud
  9. Open up Adafruit Mobile App and connect via the controller module
  10. Button presses should be indicated via the serial monitor

Code Organization:

Summary

This code was built using the Adafruit Bluefruit example code as a base. In an attempt to provide a safe simple path to a drivable robot the code that students need to modify was extracted into two files (MiniBot.cpp and MiniBot.h). In order to get a drivable robot students should only have to modify sections of the code associated with each button press or release in Minibot.cpp.

Safety Features

  1. Bluetooth connection dependent: Commands can only be executed when the BLE shield is connected to the controller. If the connection fails during operation a "stop_all_motors" function is called to immediately stop the robot's movement.

    • *The stop_all_motors functioni will have to be modified to include any motors added by each team. Recommend testing this feature immediately after each movement is added.
    • *Since this safety feature is dependent on the program executing special care will need to be taken to ensure students do not add any infinite loops. Potential inclusion of a watchdog timer or similar feature that will reset arduino in this event may need to be added.

  2. Arduino Watchdog Timer: The onboard watch dog timer feature of the arudino has been enabled to 2 seconds. If the wdt_reset(); function is not called within 2 seconds the arduino will reset itself and boot into the diabled state. The intent is to prevent any inadvertent infinite loop conditions where students lose positive control of the robot. Any programmed in routines with built in delays will have to take this into account.

Autonomous Mode

A safe approach to autonomous mode still needs to be determined. Proposal will be to tie the autonomous operation to one of the four available buttons. The robot will begin autonomous mode when the button is pressed and end autonomous mode when the button is released.

Motor Control Notes:

Motor control will utilize two Cytron MD30C's which are designed to drive a medium to high power DC Brushed motor with current capacity up to 80A peak and 30A continuously. The MD30C is capable of operating in two modes 1) Sign-magnitude mode or 2)Locked anti-phase mode. In order to simplify wiring and coding we will be using the second option for control.

In order to use the MD30C in Locked anti-phase mode we will need to do a few things:

  1. Move Jumper "JP6" from INT PWM to EXT PWM. See page 6 of the user manual for a picture.
  2. Connect the PWM input pin of the MD30C to +5VDC
  3. Connect PWM pin of the Arduino to the DIR pin of the MD30C
  4. Connect a Digital Output pin of the Arduino to the PWM pin of the MD30C, HIGH will enable the motors, LOW will disable them.

In this configuration the motor will operate as follows:

  1. Motor will stop if the Duty Cylce = 50% (PWM value = 127)
  2. Motor will run forward if the duty cycle is > 50% (PWM value > 127)
  3. Motor will run backward if the duty cycle is < 50% (PWM value < 127)

Resources:

  1. BLE Shield: https://learn.adafruit.com/adafruit-bluefruit-le-shield?view=all
  2. Arduino IDE https://www.arduino.cc/en/Main/Software
  3. Motor Driver Manual https://docs.google.com/document/d/178uDa3dmoG0ZX859rWUOS2Xyafkd8hSsSET5-ZLXMYQ/edit
  4. Motor Driver Tutorial https://tutorial.cytron.io/2013/07/29/controlling-md10c-with-arduino/
  5. Arduino Tutorial Lab software http://fritzing.org/home/
  6. Arduino 101 Presentation https://docs.google.com/presentation/d/1fccgT9k_PEGMhfhKkyhitRH8724WnI6jg2k4WSA4pfA/edit?usp=sharing