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 Post subject: Fuses and debugging
PostPosted: Wed Apr 18, 2012 11:03 am 
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Joined: Wed Jan 06, 2010 7:47 pm
Posts: 25
Hi,

I've noticed in several threads people being unsure about what fuse configuration to use for the PIC. The threads are too long to check if anyone's answered but all you need to set is:

HS oscillator
WDT off
PWRT disabled

Also, if you want to debug the PIC, you can solder a PICkit ICSP header by:
o Pulling pins 27 and 28 out of the socket
o Soldering pin 28 of the socket to pin 13.
o Soldering pin 17 of the socket to pin 12.
o Remapping DIN to LATC2 and _F_CS2 to RC1 in hardware.h and change the appropriate bits in the tristate in hardware.c. Make sure that RC1 is 1 on boot.
o Soldering wires to pins 1, 19, 20, 27 and 28 of the PIC and putting them on a PIN header as such:

Header PIC Function
1 1 MCLR
2 20 Vcc
3 19 GND
4 28 PCD
5 27 PGC

Make sure that you make the debugger *always* use target power, raising VCC to 5V would be bad. And make sure you actually have a pull-up on MCLR, not soldered it to VCC to save a resistor, 12V on 3.3V would be even worse. :-P


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 Post subject: Re: Fuses and debugging
PostPosted: Wed Apr 18, 2012 1:23 pm 
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Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
I don't understand what this will do.
What is a "fuse configuration" for the PIC?

I suggest to build a separate board instead of pulling and soldering pins at the Minimig board.

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 Post subject: Re: Fuses and debugging
PostPosted: Wed Apr 18, 2012 1:32 pm 
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Joined: Wed Jan 06, 2010 7:47 pm
Posts: 25
The fuse configuration is the low level system configuration of the PIC. It is set when the PIC is programmed and generally doesn't get reprogrammed by any bootloader. If you get it wrong, the PIC will generally either not work (ie. if the wrong oscillator is selected) or misbehave (ie. if the watchdog timer is enabled).

Also, I soldered the wires onto the pins of the PIC, not the Minimig. The only wires soldered on the Minimig are just the two unused PIC IO lines redirected to DIN and CS2. It could also be done with a little piece of veroboard with pins on the underneath instead, to leave the Minimig completely unmodified, but this is only ever useful for firmware development anyway, a user would never have to do it.


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 Post subject: Re: Fuses and debugging
PostPosted: Thu Apr 19, 2012 9:19 am 
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Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
Ah thanks for making it clear :)
I never progged a PIC due to missing programming device, so I aways used its pre-flashed static tiny-bootloader.

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JMP $00000BED ; will guru-meditation until next morning


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