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nisse
Joined: 14 Dec 2006 Posts: 50
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Posted: Wed Apr 09, 2014 9:53 pm Post subject: No response from meg640 |
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Hi
I have a meg640 that has been working fine untill just now.
I was programming it from Bascom with a USB-ISP programmer when downloading suddenly slowed down. It finished, but in more than double the normal time.
After this the chip doesn't work, I don't even get any response when trying to reprogram it, no chip ID, nothing but unknown chip FFFFF.
The programmer works, tried it with other chips. The meg640 is run from an external clock.
I suspect a fuse bit or two got messed up...
Any ideas on how i can solve this? |
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albertsm
Joined: 09 Apr 2004 Posts: 5913 Location: Holland
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Posted: Thu Apr 10, 2014 10:03 pm Post subject: |
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it is simple to solve : connect a clock signal (for example oscillator output from a working avr circuit) to the xtal input. Look in the pdf to see which pins server as input and output.
then change the fuse bytes to the proper value.
some times pulling the usb cable and plug it again can help too. when you use the jumper to power the circuit you need to take care not to draw too much current from the usb port. _________________ Mark |
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nisse
Joined: 14 Dec 2006 Posts: 50
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Posted: Fri Apr 11, 2014 6:32 am Post subject: |
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Thanks Mark, but its already running from an external oscillator |
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albertsm
Joined: 09 Apr 2004 Posts: 5913 Location: Holland
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Posted: Fri Apr 11, 2014 8:58 am Post subject: |
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but is that external osc still working ?
and does the programmer still work ? _________________ Mark |
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nisse
Joined: 14 Dec 2006 Posts: 50
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Posted: Fri Apr 11, 2014 10:26 am Post subject: |
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yes
yes
Guess I have to get the 0.4mm solder iron out and replace that AVR |
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Paulvk
Joined: 28 Jul 2006 Posts: 1257 Location: SYDNEY
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Posted: Sun Apr 13, 2014 11:42 pm Post subject: |
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Hello nisse
Have you tried a 1Mhz clock to the AVR others have noted that this has worked
Regards Paul |
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