LingDong-/avrlass

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AVRLASS - an AVR Lightweight ASSembler (and disassembler)

AVRLASS is a minimalistic assembler and dissasembler for AVR microcontrollers. It is written in plain JavaScript, and runs on Windows, Mac, Linux and the browser. It is both a command-line utility and a JavaScript library.

Here you can try AVRLASS in the browser. This online IDE also features SerialUPDI functionality, so you can write a program and upload it to your board all on a webpage, client-side.

AVRLASS does not have hardcoded device information (e.g. flash/RAM size) for all the AVR's out there, but it will try to read the information from the .inc file you include. You can specify the instruction set (AVRe+/AVRrc/AVRxt...) of your device, so it will warn you if an instruction is not available. Individual devices sometimes have additional missing instructions in addition to those of its family's, and for these, you'll need to read your datasheet.

AVRLASS is most tested on old and new ATtiny microcontrollers, especially on the new tinyAVR 0- and 1- families, but should work for all AVR's as long as the appropriate include files are provided.

Usage

Command-line

The command-line executable is avrlass.cli.js, you can run it with node avrlass.cli.js, or, make a bash alias for it, or, download a pre-compiled binary if you don't even have node.js.

$ avrlass --help
avrlass - AVR Lightweight ASSembler
usage:
  avrlass [options] src.asm 
options:
  -D <macro>=<value> Define macro
  -I <dir>           Add directory to search path
  -o <file>          Write output to file, extensions: .hex/.bin/.json
  -t <arg>           Instruction Set: AVR/AVRe/AVRe+/AVRrc/AVRxm/AVRxt
  -d                 Disassemble instead of assemble
  -h                 Print this message

If assembly is successful, you'll see a summary of memory usage for your chip, e.g.:

__SEGM_|__CODE_|__DATA_|__USED_|__SIZE_|__USE%_
 .CSEG |    34 |     0 |    34 |  4096 |  0.8% 
 .DSEG |     0 |     0 |     0 |   256 |    0% 
 .ESEG |     0 |     0 |     0 |   128 |    0%

Library

Simple usage:

// assembly
const {asm_to_hex} = require('./avrlass.js');
// disassembly
const {hex_to_asm} = require("./avrdass.js");

let hex = asm_to_hex(`
ser r16
sts 0x401,r16
sts 0x404,r16
`);

console.log(hex);

console.log(hex_to_asm(hex));

Advanced usage:

const {
  device,new_context,parse,compile,assemble,to_ihex,print_summary
} = require('./avrlass.js');

device.instr_set='AVRxt';

let context = new_context({});

let lst = parse(`
ser r16
sts 0x401,r16
sts 0x404,r16
`,pth=>fs.readFileSync(pth).toString(),context);

let ins = compile(lst,context);
console.log(print_summary());
let code = assemble(ins);
let hex = to_ihex(code);
console.log(hex);


//disassembly
const {disass, from_ihex} = require("./avrdass.js")
let bytes = from_ihex(hex);
let out = disass(bytes);
console.log(out);

Downloading include files

Include files are not included in this repository. You can download them from Microchip's website: https://packs.download.microchip.com

These so-called "DFP packs" are in fact zip archives. Once extracted, the .inc files can usually be found in avrasm/inc folder.

The Makefile includes some scripts to automatically download and snatch the .inc files for some common AVR families. e.g.:

make download_attiny
make download_atmega
make download_avrdx

Notes

Most assembly directives are supported, .if, .else etc.
Most C preprocessor directives are not supported, #if, #else etc, except for those appearing in official .inc files. Use assembly counterparts instead, or, perhaps, run it through a C preprocessor first.

References & Links

Instruction set manual https://ww1.microchip.com/downloads/en/devicedoc/atmel-0856-avr-instruction-set-manual.pdf
AVRASM2 manual https://ww1.microchip.com/downloads/en/DeviceDoc/40001917A.pdf

Some other AVR assemblers include:

AVRASM2 -- Atmel/Microchip's official assembler that comes with their IDE https://microchipdeveloper.com/swtools:avr-asm
avr-as -- Assembler that comes with AVR-GCC https://gcc.gnu.org/wiki/avr-gcc
AVRA https://github.com/Ro5bert/avra
GAVRASM http://www.avr-asm-tutorial.net/gavrasm/index_en.html

LingDong- / avrlass