atmega8a fuses help

Development Boards MicroMod
1

Hello everyone

I´am working in a project with the atmel atmega8a MCU. I´ve designed a code that works with an external 16MHz crystal. For that reason i burn the atmega8a´s fuses with the AVRISPmkII programer (HIGH FUSE:C9 LOW FUSE:FF) for a external 16MHz crystal. I test the functionality of the system with a atmega8a PU and this works perfectly. Now i´m trying to do the same in a PCB with the atmega8a AU but the burn fuses process don´t work in the same way. After this process the atmega8a AU MCU doesn´t work again and the programer can´t recognize it.

It´s something different in the burn fuses process between the atmega8a PU and the atmega8a AU?

anybody knows why happens this???

I hope you can help me with this trouble.

I´ll been waiting your answer.

Thanks a lot.

2

This question is both late and silly but are you sure you are supplying 5v to the MCU? The datasheet says you need to supply a min. of 4.4v to run at 16mhz. I’ve swapped MCU’s to a lower voltage supply (when I wasn’t paying attention) and had similar issues in the past.

3

Verify that the crystal and two capacitors are correctly connected on the PCB.

/mike