Unable to erase ATTiny841

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I'm bringing up a new PCB using an ATTiny841.  Via Atmel-ICE, I can read the device signature and set fuses (I've set SUT_CKSEL to EXTCRES_8MHZ_XX_1KCK_16CK_16MS for a 16 MHz crystal), but when I try to program my ELF I get the error below.  I've dialed the interface speed down to 100 kHz, but still no dice.  Any suggestions?  Thanks.

 

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A ceramic resonator and a crystal are two different things.  If you really can still set the fuses, pick the >8MHz crystal CKSEL.

 

In consideration of others, please RTFM!

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The only crystal-only options are for low-frequency crystals (the frequency range isn't specified in the datasheet).  All the > 8 MHz options are "crystal oscillator/ceramic resonator," i.e. it's the same selection whether you're using a crystal or a resonator.

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All speculation...

 

That AVR8 family allows (requires?) clock source selection with CLKCR, right?

 

What if ... the AVR stays alive long enough for a short transaction such as signature read, but then starts up when /RESET is released after that transaction and CLKPR is set to a non-existent clock source?

 

Perhaps a way to test that would be to hold the AVR in reset at power-up and see if multiple transactions can be done.

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