AVR Port G

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Hi folks,

    i am working with an ATMEGA12816AI. I have some problems using the pins
of PORT G  as normal I/O. It seems that the Mega128 doesn't want to turn the
ALE,WR,RD,TOSC1 and TOSC2 pins as normal I/O. I am sure that the processor
isn't i M103 compatibility mode because the code perform a MUL instruction
(and i test the result with a JTAG debugger). On the datasheet Atmel writes
that the processor will use the pins of PORT G for special function ONLY if
activated, alias the AS0 bit in ASSR for PG4/PG3 and the SRE bit in MCUCR
for PG0/PG1/PG2. After a reset those peripherals are disabled.

      Any suggestion ?






Re: AVR Port G
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Where you found information that mul instruction doesn't work on the
mega128 in the mega103 comaptibility mode?

Did you read the extended fuse byte and look at M103C value?

Regards,
--
Artur Lipowski

Re: AVR Port G

When i read  "JTAG ICE->Fuses" in AVR studio 4.08, it show the following
fuses programmed:

ATmega103 Compatibility Mode (M103C=0)
On-Chip Debug Enabled (OCDEN=0)
JTAG Interface Enabled (JTAGEN=0)
Serial program downloading (SPI) enabled (SPIEN=0)
... and other fuses about the boot flash size, brown out detection and clock
option.

so i thought that it means "if M103C is equal to 0 then ATmega103
Compatibility mode is active".

I WAS WRONG. (and the datasheet show it in table 118 on page 289)

Moreover, i thought that Atmel ship their Mega128 ready to go for what they
are. I was wrong again. You have to unprogram M103C fuse to enable the new
pins features.

Finally, the "Mega103 compatibility mode" doesn't regard the instruction
set.


Many thanks Artur.



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processor
instruction



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