On 5/2/07, Crist=F3v=E3o Dalla Costa <cdallacosta@gmail.com> wrote:
> Hello
>
> I'm encountering weird problems with a PIC18F4525. I'm working over a des=
ign
> I have working perfectly for over a year. The problem happens when I use =
the
> SPI module.
>
> The circuit uses 10 AD channels, PWM, capture, USART and now the SPI in
> master mode . I did have a version that also used SPI without any problems
> but that one used TMR2 for a 2 kHz clock. Now I'm using TMR2 for a 100 kHz
> clock and so I'm driving SPI from clock/64. So here's the weird stuff that
> happens when I enable SPI communication on the main loop:
>
> - I can't touch the CCP1 pin, RC2. If grounded or simply touched upon wit=
h a
> wire the processor will latch or reset. Configuring it as output doesn't
> help.
> - When communicating to the PC via USART the processor will reset or latch
> in a minute or two.
> - 20% of the times the processor is started from reset, it'll latch.
> - the scope shows a 0,5 Vpp, 100 kHz square wave out of the CCP1 pin
> regardless of being set as input or output. This mirrors the PWM pin next=
 to
> it.
> - disabling pwm makes everything stop working.
>


Have you made sure you have decoupling capacitors and a decent power
supply for the PIC and the MAX232 and the other chips? That's often
the problem I encounter when breadboarding circuits - not enough caps.


-Scott

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