PLEASE NOTE: I no longer actively maintain this project. Pull requests are welcome, but development has halted and issues are unlikely to gain a response.

avr

avr is an implementation of Atmel's AVR microprocessor specification in the Go programming language.

Note: this package is a work-in-progress. More to come shortly.

Features

Implements entire AVR instruction set, with the exception of BREAK, DES, SLEEP, SPM and WDR.
Emulates various hardware modules:
- digital GPIO pins
- timer/counter
Accurately supports individual MCUs:
- ATtiny4/5/9/10
- ATmega48/88/168
- more to come soon!

Installation

avr is go-gettable:

# go get github.com/kierdavis/avr/cmd/avrem

Usage

The avrem command (in the "cmd" subdirectory) is a command-line interface to the emulator. To try it out, run it with an Intel HEX file like so:

# avrem program.hex

Flags include -mcu to specify the name of the MCU spec to use, -mcus to list the names of all available MCU specs, and -freq to specify the execution frequency.

The "programs" subdirectory contains example programs. Many of these are Arduino programs, and have precompiled IHEX program files for a number of MCUs present in the same directory.

Running the "blink" example for a 16 MHz ATmega168:

# avrem -mcu mega168 -freq 16 programs/blink/blink-atmega168.hex

Note: currently, running the blink program (and probably other programs, when they are added) will produce about 20 "access of unmapped I/O port" warnings. This is simply due to the program initialising hardware subsystems that are not yet implemented in the emulator.

Performance

The maximum unthrottled clock rate approaches 35 MHz on my 2.3 GHz Intel i7 processor. Real AVR microprocessors range from 1 to 20 MHz, so this software can in theory simulate an mid-range AVR processor almost twice as quickly as the physical implementation.

Packages

github.com/kierdavis/avr - miscellaneous shared code
github.com/kierdavis/avr/clock - manages synchronisation between concurrent processes of emulator
github.com/kierdavis/avr/emulator - implementation of CPU emulator
github.com/kierdavis/avr/hardware/gpio - implementation of digital GPIO pins
github.com/kierdavis/avr/hardware/timer - implementation of timer/counter module
github.com/kierdavis/avr/loader/ihexloader - links Intel HEX file parser with loading programs into emulators
github.com/kierdavis/avr/spec - specifications of the many different models of AVR processor (MCUs)

License

This source code is distributed under the MIT license.