ATTiny85 port (work in progress)

I wanted a very small arduino type chip and foud out about a soic version of the attiny85v. My aim is a chip with a pull-up resistor to the reset pin. so a internal clock on 8Mhz. the fuse settings reflect this. here is my attempt at a altered hardware folder for the arduino ide. of course you cannot use the normal upload procedure and have to use icsp to program the chip because the attiny does not have a hardware UART.

unfortunately i have had no time yet to test the files, but here is wat i deduced by looking at the original atmega168 pdf and the pins_arduino.c and pins_arduino.h files and a very good explanation of the workings from here:

So this is the changed pins_arduino.c file:

  pins_arduino.c - pin definitions for the Arduino board
  Part of Arduino / Wiring Lite

  Copyright (c) 2005 David A. Mellis

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA

  $Id: pins_arduino.c 254 2007-04-20 23:17:38Z mellis $
  adapted to ATTiny85 2010-05-25 22:19:10 by swc

#include "wiring_private.h"
#include "pins_arduino.h"

// On the Sanguino board, digital pins are also used
// for the analog output (software PWM).  Analog input
// pins are a separate set.

//                  +-\/-+
//            PB5  1|    |8  VCC
//     (AI 3) PB3  2|    |7  PB2 (AI 1)
//     (AI 2) PB4  3|    |6  PB1 PWM
//            GND  4|    |5  PB0 PWM
//                  +----+

#define PB 1

// these arrays map port names (e.g. port B) to the
// appropriate addresses for various functions (e.g. reading
// and writing)
const uint8_t PROGMEM port_to_mode_PGM[] =

const uint8_t PROGMEM port_to_output_PGM[] =

const uint8_t PROGMEM port_to_input_PGM[] =

const uint8_t PROGMEM digital_pin_to_port_PGM[] =
      PB, /* 0 */

const uint8_t PROGMEM digital_pin_to_bit_mask_PGM[] =
      _BV(0), /* 0, port B */

const uint8_t PROGMEM digital_pin_to_timer_PGM[] =
      TIMER0A,       /* 0  - PB0 */
      TIMER1A,       /* 1  - PB1 */
      NOT_ON_TIMER,       /* 2  - PB2 */
      TIMER1B,           /* 3  - PB3 */
      TIMER1B,             /* 4  - PB4 */

and this the boards.txt file




of course i should make one for the attiny13 as well

I have not done the analog mapping in wiring_analog.c yet. first i have to find out how that works. same with pwm. maybe the attiny2313 port wil clarify it.

remember, this code is not tested yet, but pure to see if I missed something. i encourage everybody to post comments and improve on this.

*update addedattiny85.upload.using=avrispmk2 to the boards.txt file. and removed attiny85.upload.protocol=stk500

Are you able to upload using the IDE?

How did you find the , it is dead for me, and the Way-back machine says the last update on that site was in 2008 !?

Thanks, David


Did you click the link or copy-and-paste it? It looks like the forum software truncated the URL and placed an ellipses on the end.

@dpharris: sorry. url was not complete. now it is. please reload this page and click the link

@coding badly: no no upload due to missing uart(serial input) on the attiny

I believe we're talking past each other. Let me try again...

I think it's possible to get the IDE to upload using an ICSP. I tried with an ATtiny84 using IDE version 0017. It doesn't work. I think the problem has something to do with the processor name. I believe Rene Bohne got something similar to work but he had to modify and rebuild the IDE.

Have you tried uploading a Sketch to an ATtiny85 through an ICSP using the IDE? Or do you upload Sketches from the command-line?

I believe I've had the Arduino IDE working with direct upload for both AtTiny84 and AtTiny85 at some point.

If my memory serves me right, one issue was with Arduino constructing a mcu identifier not recognized by Avrdude. Knowing the identifier created by Arduino however, you can easily patch the avrdude.conf file to fix the "unknown part" issue.

no, i never tried. will keep you posted.

If my memory serves me right, one issue was with Arduino constructing a mcu identifier not recognized by Avrdude.

That's the problem!

Knowing the identifier created by Arduino however, you can easily patch the avrdude.conf file to fix the "unknown part" issue.

Add an entry for "m84" (or "m85")?

Add an entry for "m84" (or "m85")?

I don't have my notes to verify against, but I believe this is correct (avrdude expects "t84"). There was also some tossing of ideas to patch the IDE to help with this, but I don't remember seeing anything from that make it to 0018.

Anyhow it should be possible to upload from within the IDE and even with an all empty core you're quickly up and running without having to learn new tools.

Nice! Thank you!

I'll play around with it when I get back from vacation and report what I find (but I suspect macsimski will be reporting back much sooner).

I have the same issue in 17 with my 84, it always comes back invalid part m84, I was getting around to that question just have not yet

NOW that that is resolved, when doing the exact same thing in 18 it always comes back with a not in sync error, even though the 2 are setup identically

Well. I finally had some time to look into the stuff. it looks promising, but i was yelling to early. >:( A lot of files in the core directory need to be changed to get the things working. with the above files and a bare minimum sketch i get a compile error. after removing the v behind attiny85v that was changed into acompile error in WInterrupts.c complaining that EICRA was not defined. this is true because this is not a atmega8:

#if defined(__AVR_ATmega8__)
#define EIMSK GICR

[/code] so there is something wrong with:

if !defined(AVR_ATmega8)

but i have not found the place where that would be defined. a folder search in the core dir did not yield a file.

I got an error when I tried to compile, I forget what it was but I'll tell you later. Would this work on an attiny45 too?

so there is something wrong with:

if !defined(AVR_ATmega8)

but i have not found the place where that would be defined

AVR_ATmega8 is defined by the compiler from the mmcu option which the Arduino IDE gets from boards.txt (Whew! That sentence overran.) ...

For an ATtiny85 or ATtiny85V AVR_ATtiny85 is defined (but not AVR_ATmega8).

Ok. that makes sense. i think i can do without special cases and make the whole cores files attiny85 only. I get the feeling that the #if defined is only needed to make one cores dir for a few very similar AVR's. maybe later someone can add the special cases for a attiny84.

I was incorporating the latest developements into the first post but i'm a little ambivalent about it. of course it is nice to have the latest version available, but it could happen that someones comment becomes obsolete. that is confusing at the least...

i will not do that again.

This is fun! i now have the following files open on my mac:

attiny85.pdf atmega8a.pdf atmega168.pdf

arduino with a bare minimum sketch (so only setup() and loop() are there)

and bbedit for the editing of my source files.

I hit run in arduino and look at the lines of errors i get.

../Attiny85/cores/arduino/wiring_analog.c: In function 'analogWrite':

../Attiny85/cores/arduino/wiring_analog.c:86: error: 'TIMER1A' undeclared (first use in this function)

../Attiny85/cores/arduino/wiring_analog.c:86: error: (Each undeclared identifier is reported only once

../Attiny85/cores/arduino/wiring_analog.c:86: error: for each function it appears in.)

../Attiny85/cores/arduino/wiring_analog.c:88: error: 'TCCR1A' undeclared (first use in this function)

../Attiny85/cores/arduino/wiring_analog.c:91: error: 'TIMER1B' undeclared (first use in this function)

in this order i lookup all the acronyms like TIMER1Ain the atmega168 pdf and find out what they do. then i lookup the same function in the attiny85.pdf and change the according cores file.

a lot of work, but is not to difficult.

heh, god bless the search box

and the find of bbedit is fabulous! pfew. i'm half way through the files. have to call it a night now. maybe tomorrow more.

i had to guess with the timers because obviously the attiny has less of them. well we will find out later.

well I know I appreciate the work people put into porting the arduino functionality to these tiny chips

and even though I dont have a application where a 85 would fit in, I know it probably wont be long before I do

Thanks for your efforts, and keep up the good work