Q: Fixing ATTINYs with AVR ISP mkII

[JamesHowlett]

Hello,

I have been working on a controller board which drives some mosfets and LEDs. Along the way I fried some ATTINY 44 chips and some are not programmable with my arduion uno borard because either I set the pins 7 8 and 9 of ATTINY as outputs and arduino uno as ISP can no longer supply current to these pins or I set them low at the setup so that some pins are shorted, either way if I want to burn a new sketch to the chips, arduino shorts out and disconnects from the com port. But there is no problem with the functionality of the arduino itself.

I have found a project like this to repair broken ATTINY chips http://www.instructables.com/id/AVR-Attiny-fusebit-doctor-HVSP/
But I am not sure that whether I really want to build the circuit or not.

My question is: Is it possible to repair the chips with Atmel's AVRISP mkII and AVR studio as the circuit above does? I never worked with an AVRISP and AVR studio before and I need some advice.

Regards
Oz

[mikerj]

If you have cleared either the RSTDISBL or the DWEN bit in the configuration fuses, or you have somehow managed to set the SPIEN bit then you need a high voltage programmer to perform any further programming operations.  There is no way around this.  The AVRISP is not a high voltage programmer, so will not help in this case.

If the configuration fuses still permit low voltage programming, then it shouldn't matter what you do to the SPI programming pins within your ATTiny code, since all programming operations are performed under reset.  It's possible that the ISP code you are running on your Arduino is not written very well; the programmers data and clock lines should remain tri-stated until the programmer asserts the reset signal on the chip it's programming.

[dannyf]

Is it possible to repair the chips with Atmel's AVRISP mkII and AVR studio as the circuit above does?

If avrisp mkii / avr studio can generate a compliant high voltage.

I wrote a attiny fuse restorer using the serial protocol. It is very simple.