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Arduino with C / make on ubuntu

07 Sep 2016

As I am not really a C / make person, let’s document rather trivial findings on how to compile and deploy arduino based project without using Arduino IDE. It’s a well known fact that most arduinos out there are exclusively utilized for LEDs blink, so who I am to argue? This is how you do it in C:

#include <avr/io.h>
#include <util/delay.h>

#define BLINK_DELAY_MS 2000

int main (void) {
    /* set pin 5 of PORTB for output*/
    DDRB |= _BV(DDB5);

    while(1) {
        /* set pin 5 high to turn led on */
        PORTB |= _BV(PORTB5);
        _delay_ms(BLINK_DELAY_MS);

        /* set pin 5 low to turn led off */
        PORTB &= ~_BV(PORTB5);
        _delay_ms(BLINK_DELAY_MS);
    }
}

To compile and deploy let’s use the following Makefile

name = led

eeprom = target/$(name)
hex = $(eeprom).hex
source_files = $(wildcard src/*.c)
object_files = $(patsubst src/%.c, target/%.o, $(source_files))

.PHONY: clean

all: clean build

clean:
        @rm -rf target

build: $(hex)

run: $(hex)
        @avrdude -F -V -c arduino -p ATMEGA328P -P /dev/ttyUSB0 -b 115200 -U flash:w:$(hex)

$(hex): $(object_files)
        @avr-gcc -mmcu=atmega328p $< -o $(eeprom)
        @avr-objcopy -O ihex -R .eeprom $(eeprom) $(hex)

target/%.o: src/%.c
        @mkdir -p $(shell dirname $@)
        @avr-gcc -Os -DF_CPU=16000000UL -mmcu=atmega328p -c -o $@ $<

Which contains quite a few magical constants, but it’s ok for now. Now we only need to install few command line tools

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

That’s it, connect your Arduino to USB0 (if not, fix the Makefile), and run make run. Et voilà, another blinking LED. Before we proceed with drawing of the rest of the owl, let’s see how we could use CLion, to make our work a bit more comfortable.

First, let’s add the following CMakeLists.txt to our project (stolen mostly from this guy):

cmake_minimum_required(VERSION 3.0)
project(led)

set(DEVICE "atmega328p")
set(FREQ "16000000")

set(CMAKE_C_COMPILER avr-gcc)
set(CMAKE_CXX_COMPILER avr-g++)

include_directories(/usr/lib/avr/include)

set(CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "")

set(CMAKE_C_FLAGS  "-Os -mmcu=${DEVICE} -DF_CPU=${FREQ}UL -std=gnu99 -Wl,--gc-sections")
set(CMAKE_CXX_FLAGS "-Os -mmcu=${DEVICE} -DF_CPU=${FREQ}UL -Wl,--gc-sections")

set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/target")

set(SOURCE_FILES src/led.c)

add_executable(${PROJECT_NAME} ${SOURCE_FILES})

add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD COMMAND avr-objcopy -O ihex -R .eeprom ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME} ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME}.hex)
add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD COMMAND avr-objcopy -O ihex -j .eeprom --set-section-flags=.eeprom="alloc,load" --change-section-lma .eeprom=0 ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME} ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME}.eep)
add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD COMMAND avr-size ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/${PROJECT_NAME} --mcu=${DEVICE} --format=avr)

Run build, and it compiles from the IDE. For deployment create a simple run configuration in CLion IDE (not sure if there’s a way to do that with CMake). Anyhow, now you have a proper IDE to support you in LED blinking endeavour.

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