Gen7 1.2 Firmware lost?

Hi! thaks to all for the support.
I'm just finished my reprap prusa mendel and need to configure for my step configuration, Z-Axis-prusa and other stuff
I've Noticed sometimes when my Gen7 V1.2 firmware boots, no runs at all. Led for motors doesn't lit. , reprap program can't communicate... then need to reflash/refirmware for work again.
Sometimes doesn't wanna reflash and one time kill other 644p
This issue happend in twice 644 and one 644p chips.
Have a little ATX power supply from an old via epia pc 80w.
When boots, all looks runs fine (motors, heater, optos, temp) and can move, test.....
That happend with or without motors plugged, so i think isn't a supply fault problem.
This can be a fuse issue (raise vcc) like v1.3 to v1.3.1?
TIA

Quote

This can be a fuse issue (raise vcc) like v1.3 to v1.3.1?

Yes.

Simply follow the v1.3 to v1.3.1 upgrade instructions, these should also work on a v1.2.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks Traumflug.
If change the efuse to 0xFC my pcb is in a reset loop (motor leds on by 2 seconds... off by 2 seconds... on by 2 seconds... )
Tested with my little epia atx power supply and a 500w desktop power supply also with same result

There are no motor LEDs on a Gen7.

If you get constant resets, something is pulling down the voltage. Also commonly known as "a short".

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks. I'm really "conFUSEd" about this. I'm understand is for prevent raise voltage but i cant find where can be my short
My gen7 1.2 pcb looks runs fine: was able to print new vitamins and a lot hours working before for testing with efuse FF value.
Just now, make my second pcb. This time i made a 1.3.1 gen7 pcb with other fresh 644 and looks runs fine too but if i use 0xFC fuse instead 0xFF, loop reset in this pcb again.
When do a voltage tests, find 5.00v in ATX+5V (red wire) and 4.50v in ATX5vStandBy (purple wire) while pcb with firmware is running. Tested deatached connector and pin 5vSTB gives 4.50v (directly atx24 connector)
Tested 4.52v on atmega pins.
So, i cant understand why 5vSB pin give only 4.5 instead 5.0 need bigger capacitor? sorry i'm not proffesional

Looks like your power supply isn't in the best condition. As you obviously have a programmer and can re-upload the bootloader at any time, using the 0xFF extended fuse is fine. At worst, you corrupt firmware or bootloader when switching the voltage supply off. Re-uploading the bootloader heals this.

Also, you can try an intermediate step: extended fuse 0xFD.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks, yesterday was test 0xFD fuse and looks fine now.
Tested several times power off/on and no firmware or bootloader corrupted
I tested another working ATX PSU and gives 4.5V +5vSB pin !!! 3 of 3
Thanks again.

Edited 1 time(s). Last edit at 08/31/2011 05:45AM by danx3.

Glad to see it working. Picked up this on the wiki page: [reprap.org]

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Generation 7 Electronics	Teacup Firmware	RepRap DIY