AVR Development

Atmel AVR is a range of 8-bit RISC microcontrollers with several sub-families such as tinyAVR (also known as ATtiny) and megaAVR (also known as ATmega), amongst others. The Atmel AVR micros are well supported in the FOSS world with complete development tool chains such as a C compiler, simulator, debugger, downloader etc.

We prefer to develop in C and use standard Unix command-line tools.

An alternative is to use the Arduino Integrated Development Environment (IDE), which runs on a Java Virtual Machine (JVM) and the coding style is C++ based.

Support in Debian GNU/Linux and variants

The Atmel AVR "toolchains" have been available for Debian/Ubuntu Linux for some years. Specifically:

• binutils-avr - Binary utilities supporting Atmel's AVR targets
• gcc-avr - The GNU C compiler (cross compiler for avr)
• gdb-avr - The GNU Debugger for avr
• simulavr - Atmel AVR simulator
• avrdude - software for programming Atmel AVR microcontrollers

All the other usual tools such as make, editors, version control etc. can be used as per any other development project.

Makefile template

A template Makefile:

PROJNAME = ...
DEVICE = atmega328p
CC = avr-gcc
INCS = -Iusbdrv -I.
CFLAGS = -Wall -Os $(INCS) -mmcu=$(DEVICE) -DDEBUG_LEVEL=0
AVRDUDE = avrdude -p $(DEVICE) -c arduino -P /dev/ftdi_cable1 -b 57600 -v
USBDRV_OBJS = usbdrv/usbdrv.o usbdrv/usbdrvasm.o usbdrv/oddebug.o

# symbolic targets:
all:    $(PROJNAME).hex

.c.o:
        $(CC) -c $(CFLAGS) $< -o $@

.S.o:
        $(CC) -x assembler-with-cpp -c $(CFLAGS) $< -o $@

.c.s:
        $(CC) -S $(CFLAGS) $< -o $@

%.bin: %.o $(USBDRV_OBJS)
        $(CC) $(CFLAGS) -o $@ $< $(USBDRV_OBJS)

%.hex: %.bin
        rm -f $@
        avr-objcopy -j .text -j .data -O ihex $< $@

flash:  all
        $(AVRDUDE) -U flash:w:$(PROJNAME).hex

Downloading to target

We use avrdude with either the Arduino-compatible serial loader already in FLASH and some form of serial interface, such as the FT232R based USB-serial cables, or a Bus Pirate connected to the Atmel AVR 6-pin programming header.

In the case of the AVR-Stick, we use an 8-pin Small Outline Integrated Circuit (SOIC) testclip connected to the Bus Pirate.

External links

• Atmel AVR on Wikipedia