HVSP with AVR Dragon

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Hello there,

I have a bricked Atmega644PA because of bad fuses setting. I am not sure how were the fuses exactly set, but I cannot connect using AVR Dragon (ISP) with any clock speed. I have read however, that it is possible to unbrick the device using High voltage programming. I have never used HVSP before. Because of that, I find it hard to even wire my MCU with the Dragon. On this page ( http://www.atmel.com/webdoc/avrd... ) there is a description of HVSP dragon pinout "for all parts except ATtiny24/44/84 ":

 

hvsp pinout

 

The problem is, I cannot figure out how those pins correspond to those in Atmega644PA. Googling around I have found some example images connection to an Attiny chip. From there I derived that the connections are the following:

 

SII - MISO
SDI - MOSI
SDO - SCK
SCI - XTAL1

 

Are those valid?

The second point it, how to connect power to the MCU? Should I use on board voltage (which is 3.3 V in my situation) or should I apply it from the Dragon?

 

I would really appreciate all help regarding this issue. How exacly should look the wiring diagram for this device (Atmega644PA) and AVR Dragon?

This topic has a solution.
Last Edited: Wed. Sep 27, 2017 - 10:07 AM
This reply has been marked as the solution. 
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The 644 does not support HVSP. If you want to high voltage program it then it is HVPP and to do that involves connecting 20 wires (including +12V) from the Dragon to the 644. Just hope the 644 is not in circuit and there's nothing connected to any of those 20 pins that will "get in the way".

 

HOWEVER there is no need to use HVPP on a 644. There is nothing you can have done to the fuses that can make a 644 uncontactable using "normal" ISP. The worst you have done is set the clock source to something that is not present. If that is the case you just need to arrange to deliver a clock source to the XTAL1 pin and you can recover it using ISP.

 

I wrote a long article about how to recover "locked" AVRs in the Tutorial Forum that will explain this in more detail.
 

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I understand. I tried connecting an 8 Mhz crystal to the MCU, which I believe is in the lower "window" but that did not help. Previously there was a 10 Mhz crystal and it did not work as well. I will look for your tutorial, thank you.

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Read my tutorial - it's very likely a "crystal" is not going to be enough. The chances are you set "external clock".

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very likely a "crystal" is not going to be enough

 

See: http://www.avrfreaks.net/comment...

 

 

EDIT 

 

context 

Last Edited: Wed. Sep 27, 2017 - 08:43 AM
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It was indeed external clock source. Thank you.
 

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@Bremen: Please mark the thread as solved. Go to the post you think contributed best to the solution and click the "Mark Solution" button. Thank you!

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JohanEkdahl wrote:
Please mark the thread as solved. 

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