[avr-chat] Trouble with ATMEGA 1280 extended fuse byte

[Bernard Fouché]

Hi List.

I have the following problem:

- I use an "ATMEGA1280 V 8AU 0622".

- ATMEGA1280 data sheet (2549K-AVR-10/07) says (table 151, page 343) 
that only the lower 3 bits of the extended fuse byte can be programmed 
and all other bits should be '1'. IMHO it means that acceptable values 
are from 0xF8 to 0xFF.

- When I try to set my fuses to 0xFD (to have Brown-Out Detection (BOD) 
at 2.7volts, see table 27 page 60), avrude complains that while it wrote 
0xFD, it reads 0xF5.

- When using AVRSTUDIO4, I also read 0xF5 for this fuse byte.

- 0xF5 is 11110101 -> bit 3 is zero, not one.

Did I miss something obvious or is the datasheet wrong? If so, what bit 
3 means ?

Thanks!

 Bernard