Troubles with ATtiny85 fuses = 0xFF

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Troubles with ATtiny85 fuses = 0xFF

Postby stephane » Tue Aug 30, 2011 8:37 am

Hi,

As said in the title, I'm unable to re-program my fuses.

Configuration :
- HV Rescue shield v2.1
- Sketch v212
- Arduino IDE v022
- Arduino UNO
- Win 7

I programmed the fuses on LF = 0xE2; HF = 0x5F, then I have to reprogram to 0xE2/0xDF if I want to be able to use the reset pin for ISP programming.

I tried once with the Rescue Shield, and now, it read my fuses on 0xFF/0xFF, and I can't do anything.
I've searched, and haven't found any solution on my configuration.

I paste you the serial communication :
Select mode:
1: ATmega (28-pin)
2: ATtiny2313
3: ATtiny (8-pin) / HVSP
Selected mode: ATtiny/HVSP
Insert target AVR and press button.

Existing fuse values:
LFUSE: FF
HFUSE: FF

Enter desired LFUSE hex value (ie. 0x62): E2
Enter desired HFUSE hex value (ie. 0xDF): DF
Burning fuses...

Read LFUSE: FF
Read HFUSE: FF
Burn complete.

It is now safe to remove the target AVR.

Insert target AVR and press button.


What informations can I give you to help find the problem ?
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Re: Troubles with ATtiny85 fuses = 0xFF

Postby mightyohm » Mon Sep 05, 2011 10:02 pm

Did you insert or remove the ATtiny85 while the red (BURN) light was on? I have seen this happen before when I accidentally removed the part during the rescue operation.

If I understand your post correctly, the initial read succeeded, with reads returning 0xFF only after you tried burning the fuses once. Is that correct?

Can you measure the voltage on the 12V_SW test pin with respect to ground, while the BURN LED is on? It should be about 12V.
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Re: Troubles with ATtiny85 fuses = 0xFF

Postby mightyohm » Thu Sep 08, 2011 10:55 am

Today I confirmed that my Rescue Shield and ATtiny85 do not exhibit this problem with the fuse values shown above.

Please respond with some more information about your problem so I can help you troubleshoot further.
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Re: Troubles with ATtiny85 fuses = 0xFF

Postby Marcrob » Sun Apr 06, 2014 11:59 am

Hi I'm new to AVR microchips I say new only did it theory at college for dinosaurs.

I managed to 'brick' 4 Attiny45's and one Atmega328-PU chips on the same day.. hehe..

Lucky I had another 2 Atmega328PU chips, So i programmed one with your software from the site recently set it to automatic as i do not have serial or an FTDI chip, and built it on a bread board, I do not own a DC-DC converter so i used an BF199 NPN grounded with 1kohm resistor after i exploded an 2N3904 placed the 12v on the wrong line after the resistor heh.

I managed to follow the schematics and pinned out on a bread board and successfully unlocked the Atmega328PU chip (thankyou very much for making the information available). Only I then decided to unlock the ATtinys I have 1 ISP disabled and 3 reset disabled.. I ran these on automatic settings setting the fuse appropiately, I set up the breadboard following your schematics, for the HVSP, I pressed the go button,nothing happened the chip stayed locked.. I checked again found pin mapped to wrong pin 2 not pin 3 sigh,,, fixed that and tried again with each chip.. I kepted pressing the button and eventually the LED blinked the correct way to say hey i've unlocked your chip.. then i tested it and it had reset the fuses as expected,, so i tried with the second one and no go.. tried again no go tried again and hey it unlocked.. the other 2 won't unlock tried lots and lots of times, I do not think they are beyond repair as only the reset disabled was set on the fuses. Any idea what could be the matter with these other 2 chips... could it be timing and if so how can i change the code to match the timing of the BF199, the 12v line controlled by the atmega328PU chip.

Any ideas? would be great if there was a simple fix to this.
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Re: Troubles with ATtiny85 fuses = 0xFF

Postby mightyohm » Thu Apr 10, 2014 2:18 pm

The timing is really tricky to get right. I spent quite a bit of time tweaking the delays and optimizing my power switching circuit to get HVSP to work consistently. The best way to get this working is probably to buy one or my Rescue Shield kits, then you have a known good HW config that is verified working with the latest software.
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