next topic »

[on:]

Hello there,

Just wondering if it's feasible to "easily" make ATtiny85's into AVR programmers?
I'm making a little AVR programming box for our learning centre. I'd much rather use our centre's extreme excess of ATtiny85's for a buck each rather than use an actual Arduino. I saw that there is SPI on a diagram here http://arduinoelettronica.files.wordpress.com/2012/02/attiny85_pinout.png

I've also read that ATtiny's do not actually have native SPI, so I'm not sure if this is even possible. Or how much fuse-diving and code-diving would be involved. Or if SPI is even needed necessarily.

Any direction, suggestions, or comments are greatly appreciated. The idea is to be able to flash code for other ATtiny's, ATmega's, and maybe even other MCU's if possible.

-Nic

[Reply #1 on:]

the 85 doesnt have enough ram

maybe it could be done, I dunno, but out of the box your looking at ram and the lack of serial hardware.

[Reply #2 on:]

This one?

http://tequals0.wordpress.com/2011/09/26/attiny45-based-usbtinyisp-programmer/

[Reply #3 on:]

Hello there,

Just wondering if it's feasible to "easily" make ATtiny85's into AVR programmers?

"Easily?" No.

I'm making a little AVR programming box for our learning centre. I'd much rather use our centre's extreme excess of ATtiny85's for a buck each rather than use an actual Arduino.

Decent ISP programmers go for about $8 on eBay. There's some cheaper ones, too, but I never tried them.

With a few cheap programmers you could put your pile of Tiny85s to use as little programmable chips. Teach people to build stuff with them.

http://arduino.cc/forum/index.php/topic,148155.0.html

I've also read that ATtiny's do not actually have native SPI

The have "USI" which is hardware support for a number of serial interfaces like SPI, I2C, etc. You have to add a tiny bit of software to make it work as SPI.

[Reply #4 on:]

This one?

http://tequals0.wordpress.com/2011/09/26/attiny45-based-usbtinyisp-programmer/

OK, that surprised me...

Still, now I know how to use ATtinys as USB devices.

[Reply #5 on:]

OK, that surprised me...

Although it shouldn't. The Tiny2313 in my ISP programmer has less RAM/flash than a Tiny85.

And that begs the question: Why do they use Tiny2313s in ISP programmers? They cost more than Tiny85s and also make the PCB bigger (more expensive).

[Reply #6 on:]

not sure if im right or wrong but I have the arduino core files for the tiny85 so was under the impression it can be done




although I have never tried it yet

[Reply #7 on:]

not sure if im right or wrong but I have the arduino core files for the tiny85 so was under the impression it can be done

although I have never tried it yet

You can program them, sure. I do it every day. I was surprised to see one uses as the programmer.

Program a Tiny85 using a Tiny85 which has been soldered to the end of a USB cable.

[Reply #8 on:]

not sure if im right or wrong but I have the arduino core files for the tiny85 so was under the impression it can be done

although I have never tried it yet

You can program them, sure. I do it every day. I was surprised to see one uses as the programmer.

Program a Tiny85 using a Tiny85 which has been soldered to the end of a USB cable.

to me it would sound logical as the ATiny85 has the relevant Pins needed

MOSI, MISO, SCK, RST, +5v, GND, and not needed for ICSP but the RXD & TXD

[Reply #9 on:]

Actually you only need one Attiny85 to program an Attiny85 

For example Digispark use the Micronucleus bootloader to make a USB-enabled Attiny85

https://raw.github.com/Bluebie/micronucleus-t85/master/firmware/releases/micronucleus-1.04.hex

Schematic:

https://s3.amazonaws.com/digispark/DigisparkSchematicFinal.pdf

Digispark

http://digistump.com/product.php?id=1

There are other bootloaders, for example USBasploader:

https://github.com/embedded-creations/USBaspLoader-tiny85

And Tom Carpenter from this forum made a bootloader for the Tiny's

https://github.com/TCWORLD/ATTinyCore/tree/master/tiny/bootloaders/optiboot