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CMakeLists.txt
CMakeLists.txt
 
 
README.md
README.md
 
 
Scheme.png
Scheme.png
 
 
main.c
main.c
 
 
video.gif
video.gif
 
 

README.md

Timer based Uart Communication

Understanding of How uart, timers and interrupts are working and installing external crystal was the aim of this project.

Hardware Requirements:

  1. ATmega16A
  2. 16MHz Crystal
  3. 22pF Capacitor * 2
  4. USB to Serial Adapter. (I Used FT232 based board)
  5. Breadboard
  6. avrdude compatible AVR programmer (I used usbasp)

Software Requirements:

  1. VSCode + Extensions(C/C++, CMake, Commands)
  2. CMake
  3. avr-gcc
  4. avrdude
  5. Putty or any serial port communications program

Schematic:

Scheme.png

Notes:

For selecting proper uart speed use This website. I tried 153600 baud but I couldn't communicate through putty. any advice on why and how is appreciated.

Running steps:

Note that I used Ubuntu as my OS, so all commands here are Ubuntu commands.

  1. Project Creation:
    1. Create a directory for your project
    2. open VSCode and click **Open Folder..." on Get started page.
    3. Select created directory.
    4. Hit Ctrl+N to create a new file.
    5. type your C Code. (Use my code in main.c as a start)
  2. Config MCU to use External Crystal:
    1. I used This website to config MCU fuses. Do your config as you need. you can see the result bits under Manual Fuse Bit Manipulation section. any way my configs is: lfuse: 0xEF; hfuse: 0x99; lock: 0xFF.
    2. Open Terminal and type (Replace Lock bits with your config):
avrdude -c usbasp -p m16 -u -U hfuse:w:0x99:m
avrdude -c usbasp -p m16 -u -U lfuse:w:0xEF:m
avrdude -c usbasp -p m16 -u -U lock:w:0xFF:m
  1. Update Workspace Settings file: Open settings.json and update file content as below:
{
    "cmake.configureSettings": {
        "PROJECT": "timer",
        "MCU": "atmega16a",
        "F_CPU": "16000000",
        "BAUD": "115200",
        "AVR_PART": "m16"
    },
    "cmake.configureOnOpen": false,
    "files.associations": {
        "*.c": "c",
        "*.h": "c"
    }
}
  1. Create CMake file: Note that for portability of project configs, I separated CMake files in two part. The main CMake file which resides on root directory, is responsible for choosing project folder and set initial configs. the second CMake of is stored on each project directory and manages each project specific needs.
  2. RUN!:
    1. Connect your programmer to your system.
    2. Hit Ctrl+Shift+B or click Build & Flash in the status bar.
    3. Congratulations! you have made your fist embedded application!

Preview:

STM32 Port:

So the purpose was porting this project to stm32 board! struggling with timers and printf function was hard and challenging! But you can find some resources here:

  1. Using printf
  2. Using Timer Interrupts
  3. Using Timer Interupts, tut2

I strongly recommand using General Purpose timer for your first timer project, As I had some problem with starting Advanced timers.

NewLib problem:

Compiling and running first application in stm32 was a mind blowing problem for me! I fight so many times with cmake to accept the arm compiler and liker. Some strange errors that came across compiling process even I couldn't find a stright forward answer for them. most annoying problem was linking the project using arm library! After some reading I started using nano.specs as linker specs for compiling the project and tada!!!! the project compiled (albeit with some transparent code warnings!). I recommand reading these topics: