Programming with AVRdude

For more technical users, rather than using the Arduino IDE, they may want to program the Trinket directly with AVR-GCC as the compiler, vi/emacs as their editor and AVRdude as the uploader. That's easy to do!

Target the Attiny85 as the chip used in avr-gcc, with F_CPU at 8MHz using the internal oscillator.

To use avrdude a minor change must be made to to avrdude.conf. To figure out where the avrdude.conf is, open up a command window (windows: cmd, mac: Terminal, linux: rxvt etc) and type in avrdude -v
Look for the line System wide configuration file is ..... thats where avrdude.conf is.

Because the USB bootloader is a little different than an off-the-shelf programmer, we have to update the configuration file to have a longer erase delay. This does not affect programming bare Attiny85 chips, so you can use this configuration file with Trinkets or raw chips without any problems.

The Short Way


Download the new avrdude.conf by clicking on the button, rename the old avrdude.conf file to avrdudeconf.bak and copy this new one into the same directory

This may not work if you're not running the exact same version of avrdude that we are, in which case, just go down to "the long way" (its really not that long)

A slightly different configuration file is needed for Mac:

You can also find a Linux version of the avrdude.conf file here:

The Long Way

If you want to update your avrdude.conf by hand, its not too hard.

Open up that exact file in your favorite text editor
and find the following text

#------------------------------------------------------------
# ATtiny85
#------------------------------------------------------------
Delete the text after the Attiny85 header text starting with part and onto until the next header (in ours, that was ATmega640
Then paste in the following in the spot where you just deleted!
part
     id            = "t85";
     desc          = "ATtiny85";
     has_debugwire = yes;
     flash_instr   = 0xB4, 0x02, 0x12;
     eeprom_instr  = 0xBB, 0xFF, 0xBB, 0xEE, 0xBB, 0xCC, 0xB2, 0x0D,
	             0xBC, 0x02, 0xB4, 0x02, 0xBA, 0x0D, 0xBB, 0xBC,
	             0x99, 0xE1, 0xBB, 0xAC;
## no STK500 devcode in XML file, use the ATtiny45 one
     stk500_devcode   = 0x14;
##  avr910_devcode   = ?;
##  Try the AT90S2313 devcode:
     avr910_devcode   = 0x20;
     signature        = 0x1e 0x93 0x0b;
     reset            = io;
     chip_erase_delay = 900000;

     pgm_enable       = "1 0 1 0  1 1 0 0    0 1 0 1  0 0 1 1",
                        "x x x x  x x x x    x x x x  x x x x";

     chip_erase       = "1 0 1 0  1 1 0 0    1 0 0 x  x x x x",
                        "x x x x  x x x x    x x x x  x x x x";

    timeout		= 200;
    stabdelay		= 100;
    cmdexedelay		= 25;
    synchloops		= 32;
    bytedelay		= 0;
    pollindex		= 3;
    pollvalue		= 0x53;
    predelay		= 1;
    postdelay		= 1;
    pollmethod		= 1;

    hvsp_controlstack   =
        0x4C, 0x0C, 0x1C, 0x2C, 0x3C, 0x64, 0x74, 0x66,
        0x68, 0x78, 0x68, 0x68, 0x7A, 0x6A, 0x68, 0x78,
        0x78, 0x7D, 0x6D, 0x0C, 0x80, 0x40, 0x20, 0x10,
        0x11, 0x08, 0x04, 0x02, 0x03, 0x08, 0x04, 0x00;
    hventerstabdelay    = 100;
    hvspcmdexedelay     = 0;
    synchcycles         = 6;
    latchcycles         = 1;
    togglevtg           = 1;
    poweroffdelay       = 25;
    resetdelayms        = 1;
    resetdelayus        = 0;
    hvleavestabdelay    = 100;
    resetdelay          = 25;
    chiperasepolltimeout = 40;
    chiperasetime       = 900000;
    programfusepolltimeout = 25;
    programlockpolltimeout = 25;

     memory "eeprom"
         size            = 512;
        paged           = no;
        page_size       = 4;
         min_write_delay = 4000;
         max_write_delay = 4500;
         readback_p1     = 0xff;
         readback_p2     = 0xff;
         read            = "1  0  1  0   0  0  0  0    0 0 0 x  x x x a8",
                           "a7 a6 a5 a4  a3 a2 a1 a0   o o o o  o o o o";

         write           = "1  1  0  0   0  0  0  0    0 0 0 x  x x x a8",
                           "a7 a6 a5 a4  a3 a2 a1 a0   i i i i  i i i i";

	loadpage_lo	= "  1   1   0   0      0   0   0   1",
			  "  0   0   0   0      0   0   0   0",
			  "  0   0   0   0      0   0  a1  a0",
			  "  i   i   i   i      i   i   i   i";

	writepage	= "  1   1   0   0      0   0   1   0",
			  "  0   0   x   x      x   x   x  a8",
			  " a7  a6  a5  a4     a3  a2   0   0",
			  "  x   x   x   x      x   x   x   x";

	mode		= 0x41;
	delay		= 12;
	blocksize	= 4;
	readsize	= 256;
       ;
     memory "flash"
         paged           = yes;
         size            = 8192;
         page_size       = 64;
         num_pages       = 128;
         min_write_delay = 30000;
         max_write_delay = 30000;
         readback_p1     = 0xff;
         readback_p2     = 0xff;
         read_lo         = "  0   0   1   0    0   0   0   0",
                           "  0   0   0   0  a11 a10  a9  a8",
                           " a7  a6  a5  a4   a3  a2  a1  a0",
                           "  o   o   o   o    o   o   o   o";

         read_hi         = "  0   0   1   0    1   0   0   0",
                           "  0   0   0   0  a11 a10  a9  a8",
                           " a7  a6  a5  a4   a3  a2  a1  a0",
                           "  o   o   o   o    o   o   o   o";

         loadpage_lo     = "  0   1   0   0    0   0   0   0",
                           "  0   0   0   x    x   x   x   x",
                           "  x   x   x  a4   a3  a2  a1  a0",
                           "  i   i   i   i    i   i   i   i";

         loadpage_hi     = "  0   1   0   0    1   0   0   0",
                           "  0   0   0   x    x   x   x   x",
                           "  x   x   x  a4   a3  a2  a1  a0",
                           "  i   i   i   i    i   i   i   i";

         writepage       = "  0  1  0  0   1   1   0  0",
                           "  0  0  0  0  a11 a10 a9 a8",
                           " a7 a6 a5  x   x  x  x  x",
                           "  x  x  x  x   x  x  x  x";

	mode		= 0x41;
	delay		= 6;
	blocksize	= 32;
	readsize	= 256;
       ;
#   ATtiny85 has Signature Bytes: 0x1E 0x93 0x08.
     memory "signature"
         size            = 3;
         read            = "0  0  1  1   0  0  0  0   0  0  0  x   x  x  x  x",
                           "x  x  x  x   x  x a1 a0   o  o  o  o   o  o  o  o";
       ;
     memory "lock"
         size            = 1;
         write           = "1 0 1 0  1 1 0 0  1 1 1 x  x x x x",
                           "x x x x  x x x x  1 1 i i  i i i i";
        min_write_delay = 9000;
        max_write_delay = 9000;
       ;

     memory "lfuse"
         size            = 1;
         write           = "1 0 1 0  1 1 0 0  1 0 1 0  0 0 0 0",
                           "x x x x  x x x x  i i i i  i i i i";

         read            = "0 1 0 1  0 0 0 0  0 0 0 0  0 0 0 0",
                           "x x x x  x x x x  o o o o  o o o o";
        min_write_delay = 9000;
        max_write_delay = 9000;
       ;

     memory "hfuse"
         size            = 1;
         write           = "1 0 1 0  1 1 0 0  1 0 1 0  1 0 0 0",
                           "x x x x  x x x x  i i i i  i i i i";

         read            = "0 1 0 1  1 0 0 0  0 0 0 0  1 0 0 0",
                           "x x x x  x x x x  o o o o  o o o o";
        min_write_delay = 9000;
        max_write_delay = 9000;
       ;

     memory "efuse"
         size            = 1;
         write           = "1 0 1 0  1 1 0 0  1 0 1 0  0 1 0 0",
                           "x x x x  x x x x  x x x x  x x x i";

         read            = "0 1 0 1  0 0 0 0  0 0 0 0  1 0 0 0",
                           "x x x x  x x x x  o o o o  o o o o";
        min_write_delay = 9000;
        max_write_delay = 9000;
     ;

     memory "calibration"
         size            = 2;
         read            = "0  0  1  1   1  0  0  0    0 0 0 x  x x x x",
                           "0  0  0  0   0  0  0  a0   o o o o  o o o o";
     ;
  ;
If editing manually, Mac users should delete all references to parallel port programmers ("type = par;").

Uploading with AVRdude


Now you're ready to use avrdude. Open up your command line and enter in this line (but don't hit return)

avrdude -c usbtiny -p attiny85
Now plug in the Trinket into the computer's USB port and/or press the reset button to enter the bootloader. You should see the red LED pulsing. Now press return, you should get the same response as shown here:
If you get the response

avrdude: Error: Could not find USBtiny device (0x1781/0xc9f)

the bootloader is not active, make sure you see the red LED pulsing, press the reset button to start the bootloader again.

Programming in a Blink example


For more details on using avdude and avr-gcc, you'll need to read a detailed tutorial or book on those subjects. However, you can do a basic test by uploading the following HEX file, which will blink the #1 LED once a second on and off. (Its a bit chunky as blink.hex's go as it has all the Arduino IDE stuff in there too. If you wrote it in straight-C it would be like 100 bytes) - if you want to see the source code for this, it's basically the Arduino file->examples->basics->blink demo with 1 as the LED pin

Click the button to download it and place it in the same directory as your command prompt, in these screenshots that's C:\Users\ladyada

And uploading it with the command avrdude -c usbtiny -p attiny85 -U flash:w:trinketblink.hex
or, if that's giving errors, avrdude -c usbtiny -p attiny85 -D -U flash:w:trinketblink.hex (note the extra -D)

As before, type out the command, then press the reset button to start the bootloader and once the red LED is pulsing, hit return

When uploading, you will see a lot of avrdude: 8 retries during SPI command and similar warnings. THIS IS OK! Because of the way the ATtiny85 works, there's a small delay when writing the new program to flash, and during that delay, it cannot save the data and also send USB data at the same time. This causes the USB reply to avrdude to be delayed and avrdude to spit out the retry alert.
Last updated on 2016-06-03 at 04.00.31 PM Published on 2013-09-03 at 01.30.12 PM