[avr-chat] Failure programming efuse on AT90PWM3B

[Matthew Stephenson]

When trying to program the efuse byte on an AT90PWM3B, I get the following error:

avrdude: reading input file "0x49"

avrdude: writing efuse (1 bytes):

Writing |                                                    | 0% 0.00s ***failed;

Writing | ################################################## | 100% 0.06s

avrdude: 1 bytes of efuse written

avrdude: verifying efuse memory against 0x49:

avrdude: load data efuse data from input file 0x49:

avrdude: input file 0x49 contains 1 bytes

avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.00s

avrdude: verifying ...

avrdude: verification error, first mismatch at byte 0x0000

         0x49 != 0x01

avrdude: verification error; content mismatch

I've checked the lock bits, which are unlocked, and confirmed that I can successfully write lfuse. The efuse always reads back as 0x01, which doesn't seem right, as I've never modified it and the datasheet default is 0xF9. I'm using a USBTinyISP programmer.

Am I doing something stupid or is there something wrong with avrdude here?

- Matthew