ATMega_2560_Embedded_THT/AVR.txt

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AVR: Alf and Regards's RISC Processor
Installing AVR toolchain:
Basic requirements:
gcc-avr : a GNU C cross-compiler for specifically for AVR
avr-libc: it is a package for AVR C library
more info: https://www.nongnu.org/avr-libc/user-manual/index.html
https://exploreembedded.com/wiki/AVR_C_Library
avrdude: it is a utility that transfers codes from the UBUNTU to the microcontroller. AVR downloader uploader: software(utility program) for downloading and uploading on-chip memories of Microchip's AVR microcontrollers
arduino CLI: Arduino Command LIne Interface- Arduino CLI is a command line tool that contains all you need to easily build applications around the Arduino ecosystem.
Basic installation commands:
sudo apt-get install gcc-avr binutils-avr avr-libc
sudo apt-get install avrdude
sudo apt-get install arduino-cli or snap install arduino-cli
More info about installation: https://www.nongnu.org/avr-libc/user-manual/install_tools.html
Basic processes involved:
1)Compilation which creates object files
2)Linking the object files to create ELF files(Executable and Linkable Format)
3)Object-copy(assembly) to create hex files
4)Flashing(dumping) the hex file on the board using avrdude
more info: https://www.avrfreaks.net/forum/avr-gcc-compiling-linking-and-assembly --(pic in this website)--
Instructions to compile the code:
Compile and linking Instruction(generating object files and linking them):
avr-gcc -Os -mmcu=atmega2560 -c -o <destination_file-blinking_led> <source.c> //avoid using '-c' to avoid improper linking
Object Copy Instruction:
avr-objcopy -O ihex -R .eeprom <destination_file-blinking_led> <file_name.hex>
Programming(flashing the hex file on board):
avrdude -C /usr/share/arduino/hardware/tools/avrdude.conf -patmega2560 -cwiring -P /dev/ttyACM0 -b 115200 -D -U flash:w:<file_name.hex>:i
Execution using make:
GNU make:
The "make" utility automates the mundane aspects of building executable from source code. "make" uses a so-called makefile, which contains rules on how to build the executables. Make is different from a script as a script shows no intelligence. All instructions run blindly, without dpending on the consequences of the previous instructions.
more info: https://www3.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html#zz-1.6
makefile youtube tutorial: https://www.youtube.com/playlist?list=PLNmACol6lYY7Dzvg7jKgvMdDaDEDFnNqD
based on the makefile created..
//change parameters accordingly in makefile to make sure the correct files get executed
Instructions:
make all
make flash
Makefile:
# simple AVR Makefile
#
# written by michael cousins (http://github.com/mcous)
# released to the public domain
# Makefile
#
# targets:
# all: compiles the source code
# test: tests the isp connection to the mcu
# flash: writes compiled hex file to the mcu's flash memory
# fuse: writes the fuse bytes to the MCU
# disasm: disassembles the code for debugging
# clean: removes all .hex, .elf, and .o files in the source code and library directories
# parameters (change this stuff accordingly)
# project name
PRJ = main
# avr mcu
MCU = atmega2560
# mcu clock frequency
CLK = 16000000
# avr programmer (and port if necessary)
# e.g. PRG = usbtiny -or- PRG = arduino -P /dev/tty.usbmodem411
PRG = wiring -P /dev/ttyACM0
# fuse values for avr: low, high, and extended
# these values are from an Arduino Uno (ATMega328P)
# see http://www.engbedded.com/fusecalc/ for other MCUs and options
LFU = 0xFF
HFU = 0xD0
EFU = 0xFD
# program source files (not including external libraries)
SRC = $(PRJ).c
# where to look for external libraries (consisting of .c/.cpp files and .h files)
# e.g. EXT = ../../EyeToSee ../../YouSART
EXT =
#################################################################################################
# \/ stuff nobody needs to worry about until such time that worrying about it is appropriate \/ #
#################################################################################################
# include path
INCLUDE := $(foreach dir, $(EXT), -I$(dir))
# c flags
CFLAGS = -Wall -Os -DF_CPU=$(CLK) -mmcu=$(MCU) $(INCLUDE)
# any aditional flags for c++
CPPFLAGS =
# executables
AVRDUDE = avrdude -C /usr/share/arduino/hardware/tools/avrdude.conf -c $(PRG) -p $(MCU) -b 115200 -D
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
SIZE = avr-size --format=avr --mcu=$(MCU)
CC = avr-gcc
# generate list of objects
CFILES = $(filter %.c, $(SRC))
EXTC := $(foreach dir, $(EXT), $(wildcard $(dir)/*.c))
CPPFILES = $(filter %.cpp, $(SRC))
EXTCPP := $(foreach dir, $(EXT), $(wildcard $(dir)/*.cpp))
OBJ = $(CFILES:.c=.o) $(EXTC:.c=.o) $(CPPFILES:.cpp=.o) $(EXTCPP:.cpp=.o)
# user targets
# compile all files
all: $(PRJ).hex
# test programmer connectivity
test:
$(AVRDUDE) -v
# flash program to mcu
flash: all
$(AVRDUDE) -U flash:w:$(PRJ).hex:i
# write fuses to mcu
fuse:
$(AVRDUDE) -U lfuse:w:$(LFU):m -U hfuse:w:$(HFU):m -U efuse:w:$(EFU):m
# generate disassembly files for debugging
disasm: $(PRJ).elf
$(OBJDUMP) -d $(PRJ).elf
# remove compiled files
clean:
rm -f *.hex *.elf *.o
$(foreach dir, $(EXT), rm -f $(dir)/*.o;)
# other targets
# objects from c files
.c.o:
$(CC) $(CFLAGS) -c $< -o $@
# objects from c++ files
.cpp.o:
$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
# elf file
$(PRJ).elf: $(OBJ)
$(CC) $(CFLAGS) -o $(PRJ).elf $(OBJ)
# hex file
$(PRJ).hex: $(PRJ).elf
rm -f $(PRJ).hex
$(OBJCOPY) -j .text -j .data -O ihex $(PRJ).elf $(PRJ).hex
$(SIZE) $(PRJ).elf
main.c file for blinking of led code:
#include <avr/io.h>
#define F_CPU 16000000//16MHz
#define MS_DELAY 1000//1 second=1000 ms
#include <util/delay.h>
int main(void)
{
//pin 37-port C0
DDRC = 0xff;
PORTC = 0xff;
while(1)
{
PORTC = 0x01;
_delay_ms(1000);//1 second delay
PORTC = 0x00;
_delay_ms(1000);//1 second delay
}
return 0;
}