1. Package download and setup

There is nothing wrong with the vendor-provided tools (Atmel, now owned by Microchip), but we want the bare minimum of layers of abstraction and “help” between the text file with code and the actual programs that convert that code into a .hex file to program to the MCU. Once you understand the process, then adding layers of tooling on top to automate it is just fine.

WinAVR uses GCC (as does the Arduino platform), but forces allows us to have more control over the compiling process compared to other tools. It is old (2010 version!) …​ but it works.

The portable version can run from anywhere and does not require installing, which is handy for students and lab computers.

Download the modified Valpo copy from the GDrive docs folder: [1]

Unzip this archive, then move the folder to a location of your choosing.

Double-click on the file CreateShortcuts.bat and a black cmd.exe window will briefly pop up.

You can move the newly-created shortcut files wherever you would like.

2. avr_sim and gavrasm

gavrasm, the assembler used by avr_sim is also installed. It is available from the command window started by the AVR-CommandShell shortcut.

2.1. Colors in avr_sim

This step is not able to be automated or pre-configured, unfortunately. But it only involves editing a text file.

You can find a copy of the avr_sim manual in GDrive docs / AVR / avr_sim-gavrsim: avr_sim_Handbook_v25.pdf. What follows was obtained from reading §4.3.7 Syntax highlighting and some experimentation.

  • Color configuration is stored in two places:

    • Default system settings
      c:\Users\YourUsername\AppData\Roaming\avr_sim\avr_sim.cfg

    • Per-project settings
      project-name.pro file next to your .asm file and the .lst and .hex output files.

System default colors:

After avr_sim has run at least once on the machine, open the following file in a text editor: (AppData is a hidden folder)
C:\Users\YourUsername\AppData\Roaming\avr_sim\avr_sim.cfg

Paste the following line into that file and save it:

syhili=i255,,b;d16711680,,;k8421504,12632256,bi;c8421504,,;f128,,;l65280,,;r8388608,,b;z32896,65535,;n0,,;

The configuration file (either the system avr_sim.cfg or the project .pro) MUST end in a blank line. Otherwise the program will silently ignore the changed settings.

Before testing whether the change works, use a text editor to open up the .pro file for the project you intend to open for checking the colors. Delete the line beginning with syhili=…​ in the project file. Those are the colors that apply to that particular project only and are probably not what you wanted anyway.

  • The color settings get saved to the project file when you answer Yes to the Question dialog box asking “Project changed, save changes?”

Now, open a project with avr_sim and see that the coloring is indeed updated.

avr sim custom colors

  • You are encouraged to come up with a better color scheme and share it!

2.2. Assembly with avr_sim / gavrasm

Start avr_sim from this new shortcut. Create a new project.

Paste in the following code:

; Blink pin PB3
; ATtiny85

; Symbols defined for the ATtiny85
.nolist
.include "tn85def.inc"
.list

; what follows is to be placed in program memory
.cseg

; starting at this address
.org 0x0000
Setup:
; set PB3 to output using DDRB
    sbi DDRB, 3     ; 2 cycles, same result

Main:
; blink PB3
    sbi PORTB, 3
    cbi PORTB, 3

    rjmp Main


Assemble the code to generate a .hex file.

Run the simulation to verify that the code operates as you expect.

3. Tour of WinAVR Portable

Inside the extracted folder WinAVR-20100110:

  • Folder bin/:

    • avrdude

    • avr_sim

    • All of the AVR-GCC and AVR-binutils programs:

      • `avr-g` C compiler

      • avr-gcc C compiler and main program

      • avr-ld Linker

      • avr-objcopy Generate .lst and .hex files

      • avr-as Assembler

      • avr-size

  • Folder pn/ — Programmer’s Notepad pn.exe

  • Folder utils/bin MINGW programs, to run from a command window.

    • make

    • Convert text files. make needs Linux-format Makefile files

      • fromdos — Convert text file to use \n (Linux) instead of \r\n (Windows) line endings

      • todos — Convert text file to use \r\n (Windows) instead of \n (Linux) line endings

4. Documentation

It is somewhat useful to read random documentation found randomly on the Internet. It us much more useful to read the documentation for the specific version of AVR-libc and friends that you are actually using. Versions add features over time, usually the web version is for the latest version unless otherwise specified.

Most of the specific documentation about the tools is under this folder:
WinAVR-20100110\doc (→ ${doc} below)

  • avrdude - programming tool.
    PDF manual: ${doc}\avrdude\avrdude.pdf

  • avr-gcc - C/C++ compiler. There are two major parts of GCC that you should have separate in your mind:

    • C preprocessor cpp, which handles #define, #ifdef, and similar. ${doc}\gcc\HTML\gcc-4.3.2\cpp\index.html

    • Compiler GCC ${doc}\gcc\HTML\gcc-4.3.2\gcc\index.html
      Search for “attributes” for the documentation for things like inline/noinline, interrupt, and others which give the compiler specific information to guide the compilation and optimization process.

  • avr-libc - C standard library and extras for AVR:

    • HTML version of the manual: ${doc}\avr-libc\avr-libc-user-manual\index.html

    • PDF of the manual: ${doc}\avr-libc\avr-libc-user-manual.pdf

  • avr-binutils - Many companion tools for manipulating compiler output.

    • avr-as - assembler. ${doc}\binutils\as.html\index.html
      Directives and features of GCC’s version of assembly language.

    • avr-ld - linker. ${doc}\binutils\ld.html\index.html
      The linker is usually called by avr-gcc and not directly. It handles combining all of the compiled object files (.o) into a single executable file (.elf).

    • avr-objdump - Generates the .lst listing by taking the binary .elf and disassembling, yielding assembly language. With extra options and with code compiled with the -g option, the output also gives the source code that roughly corresponds to the assembly.
      ${doc}\binutils\binutils.html\objdump.html

    • avr-abjcopy - Generates the .hex file for programming from a binary .elf, and other related outputs.
      ${doc}\binutils\binutils.html\objcopy.html

    • avr-size - summarizes code and RAM usage.

    • avr-nm - lists the symbols defined in an object .o file.

5. Program device with avrdude

Open a command window using the AVR-CommandShell shortcut. With your "Arduino as ISP" attached to COM6:

  • avrdude -c stk500v1 -p attiny85 -b 19200 -P COM6 -U flash:w:main.hex

You likely need to change the COMx port and the .hex file name.

Table 1. Arduino as ISP connections
Purpose Nano ATtiny85 Description

RESET

D10

pin 1

reset

MOSI

D11

pin 5

Serial data in

MISO

D12

pin6

Serial data out

SCK

D13

pin 7

Serial clock
Programming is independent of HOW the .hex file was created — text editor, assembler, C compiler, Arduino IDE (Sketch → Export compiled binary), back alley bartering, etc.
1. Thr original WinAVR portable is at https://sourceforge.net/projects/winavrportable/