coconutjj / arduino

Arduino

Arduino Resources

This repository is dedicated to learning about Arduino and the ATmega328p microcontroller.

I have a Arduino UNO R3.

Important: This respository does not use the Arduino abstraction layer built on top the AVR libc. So there are no methods like digitalWrite(), setup() or loop(). If you wish to work on top of the Arduino abstraction layer, this tutorial is not neccessary, just download the Arduino IDE and hit upload.

Getting Started: Installing the development toolchain

There are several ways to obtain the Arduino developement toolchain. The easiest way is to piggyback on the avr-gcc toolchain installed with the Arduino IDE. On MacOS, you can find the toolchain at ~/Library/Arduino15/packages/arduino/tools.

However, downloading and installing the avr-gcc toolchain in a seperate directory allows for better organization and removes the Arduino IDE dependency.

The following toolchain components need to be installed

1. avr-binutils
2. avr-gcc
3. avr-libc
4. avrdude (for uploading code to the arduino)

A tutorial for installing all these components can be found at https://www.nongnu.org/avr-libc/user-manual/install_tools.html#path

There are two files, config.sub and config.guess that seem to be out of date for the latest release of avr-libc. Before the configure step, it is advisable to replace these two files with the latest version found at https://github.com/gcc-mirror/gcc/tree/master

Compile, Link and Upload

Once you have installed the toolchain, the compile, link and uplaod process to the Arduino is also not trivial. The following is the Makefile used for compiling the code in the hello-world directory. This Makefile assumes the toolchain was installed in the repository root under a directory named avr-gcc/.

CC=avr-gcc/avr/bin/avr-gcc
MMCU=atmega328p
CPU_CLK_SPEED=16000000UL
PROGRAMMER=arduino
AVRDUDE=avr-gcc/avr/bin/avrdude
OBJCOPY=avr-gcc/avr/bin/avr-objcopy

hello: hello.c
	$(CC) -Os -mmcu=$(MMCU) -DF_CPU=$(CPU_CLK_SPEED) hello.c -o hello.elf
	$(OBJCOPY) -j .text -j .data -O ihex hello.elf hello.hex

upload: hello.hex
	$(AVRDUDE) -c $(PROGRAMMER) -p $(MMCU) -P /dev/cu.usbmodem1101 -U flash:w:hello.hex:i
	

Programs

Many of the are Proof of Concepts, don't expect anything too advanced. I have a plan to make a automatic plant watering circuit. Still need to buy a soil moisture detector and pump.

SOS Program

The SOS program blinks an LED attached to PIN 7 on the arduino in a SOS pattern

Traffic Light Simulator

Simulates a Traffic light cycle

Serial UART Communication

Work in progress: A CLI and arduino program that allows for communication between the device and the computer through USB.

ATmega328p DIP edition Pin Diagram

The datasheet for the ATmega328p microcontroller can be downloaded at https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf