DC Motor Speed Controller

Table of contents

• Project description
• Hardware
• Technologies
• How to run
• Development

Project description

The main purpose of this project is to control DC motors in open loop, in order to set speed and direction in real time. One MCU and one H-bridge are used to achieve this. PC and MCU communicates writing each other custom packets. Basically, the idea is this:

• PC to MCU serial communication to set the motor parameters.
• MCU to PC serial communication to check the motor status.

MCU side

• PWM generation
• Periodically send status-packets with a timer based ISR
• Receive setting-packets with UART based ISR

PC side

• Open, set and close serial communication using unix API
• Multithreading (1 sender thread, 1 listener thread)
• Graphic Unit Interface with ncurses
• Option flags handling

Hardware

• AVR atmega2560
• DC motor
• Battery pack (6V, 2850mAh)
• L298N H-bridge

Technologies

• OS: Ubuntu 16.04
• Language: C
• PC compiler: gcc (version 5.4.0)
• MCU compiler: avr-gcc (version 4.9.2)
• GUI lib: ncurses.h

How to run

Installation

Firts of all, make sure you have installed ncurses library. If not, type:

sudo apt-get install libncurses5-dev libncursesw5-dev

To upload AVR code in your microcontroller you need avr-gcc:

sudo apt-get install gcc-avr binutils-avr gdb-avr avr-libc avrdude

AVR code can be compiled and uploaded typing :

cd avr
make
make dc_control.hex
sudo addgroup <your username> dialout
cd ..

Pc-side code can be found in "serial" directory. Run Makefile in order to compile and create the executable:

cd serial
make

After that, you are ready to run the program.

Usage

Pc-side code can be found in "serial" directory. Run Makefile in order to compile and create the executable:

./main

Main can be launched with different optional flags:

./main -l

Enable linear interpolation on avr. With this flag enabled motor direction change smoothly.

./main -f

Force avr re-upload/restart.

./main -d

Debuf mode (deprecated). Used for communication testing, GUI disabled.

Development

10.05.19

- design overall software workflow
- packet data structure
- PWM generation: motor now work properly

11.05.19

- UART basic functions

12.05.19

- timer based ISR (send status every 1 second)
- UART ISR (reading incoming packet)
- handshaking routine
- test new features: works as expected (with cutecom)

14.05.19

- start working on pc side
- set termios struct parameters
- read() and write() syscall
- makefile

18.05.19

- transmission fixes (avr side)
- handshake protocol
- serial packet_t structure
- serial functions (readPacket() and writePacket())
- packet_t data manipulation functions

19.05.19

- fixes on avr side
- fixes on readPacket() and writePacket()
- listener thread for blocking read
- mutex synch
- main testing: some bugs, but works

23.05.19

- fix bug #2
- linear interpolation for smooth speed changes

01-02.06.19

- testing different handshake protocols
- choose the definitive handshake
- add option flag -s to enable linear interpolation on avr
- add option flag -f to force avr re-upload

03.06.19

- cleaning: remove useless stuff
- fixing linear interpolation