how to save my locked AVR??

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#1
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i have several AVR(Atmega16 and Atmega64) locked. and i don't know why will lock them, maybe fuse or others.
every time AVR Studio 4 just shows me "The OCD JTAG adapter was detected, but the target device did not return a valid JTAG ID..."
now my AVR can just work with old program downloaded before, it can not be renewed by the JTAG adapter.
i have tried 4MHz crystal oscillator to save them , but it is useless.
can you help me with the simplest method?

Our Martians are beginning to learn AVR

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Are you trying to simply reprogram them with JTAG or are you trying to use JTAG as a debugger?

Which JTAG adaptor do you have , a MK1 or a MK2?

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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both. but now i can't visit my AVR with my JTAG ICE(it is the cheapest one in the market)

Our Martians are beginning to learn AVR

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I have always been able to restore fuse settings by hooking up an oscillator to the clock input of the target, using a separate power supply for the target, and erasing the target a couple of times, then re-program the clock fuses. Chances are your clock fuses are not programmed correctly.

I used 3.6864 oscillator Digi-key SE1723-ND

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If it is ONLY the lock bits and not FUSE bits, erasing should allow access to the processor for re-programming.

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Not sure if this helps, but if you're using the STK500 board, you should be able to erase the MCU using High Voltage programming...