Author Topic: Are AVR fuses resetable???  (Read 1809 times)

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Offline tristantechTopic starter

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Are AVR fuses resetable???
« on: March 11, 2009, 07:54:33 PM »
Can AVR Fuses be reset and reprogrammed? I know that RSTDISBL will brick the microcontroller, but what about the other fuses like CLKDIV8, EESAVE, etc???
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Offline Webbot

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Re: Are AVR fuses resetable???
« Reply #1 on: March 11, 2009, 11:10:30 PM »
CLKDIV8 - can certainly be reset as can 'most' of them.

Obviously you've found the 'reset disable' problem. Programmers like AVRISP mkII (and probably all of them?) connect with the reset pin. So disabling the reset will effectively mean 'disable talking to me anymore'.

You may wonder why such a fuse exists? Well its probably to stop a competitor taking your chip and reading the program out of it. So the chip becomes a read-only brick. Which for a developer is bad!

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Offline pomprocker

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Re: Are AVR fuses resetable???
« Reply #2 on: March 12, 2009, 10:03:45 AM »
Yes in the data sheet in all atmegas there is a section on high voltage programming algorithms. With this you can program, high low and extended fuses. HV programming does not depend on reset pin or isp pins
« Last Edit: March 12, 2009, 10:05:01 AM by pomprocker »

Offline want2learn

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Re: Are AVR fuses resetable???
« Reply #3 on: March 14, 2009, 01:41:08 PM »
The question that drives me hazy:

Am I, or the others crazy?


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