You have selected the XT oscillator, 4 MHz is in the range where a HS
setting with it's higher gain might be needed for some crystals needing
a higher drive level. See what results you get with this.

Peter van Hoof

--- r-vallad@unete.cl wrote:

> Hi all,
> 
> i have an extraneous behiavor of a 16f48a, the same circuit, with the
> same
> program, sometimes start about 5 minutes after power on, sometimes
> don't
> start at all and another times it works fine. still is in protoboard,
> but
> it's a simple circuit.
> 
> in software, i have this configuration (BoostC)
> 
> #pragma DATA _CONFIG, _BOREN_OFF & _CP_OFF & _DATA_CP_OFF & _WDT_OFF
> &
> _LVP_OFF & _MCLRE_OFF & _XT_OSC & _PWRTE_ON
> 
> the circuis has a external 4MHz xtal oscillator, coupled with a pair
> of
> 22nF condenser to ground. all of this is near the pic, the pic itself
> is
> decoupled with a 0.01uF and the only other component in the
> protoboard is
> a 16x2 display.
> about 50cm apart, is the "1st floor" of the circuit, a 3-8 decoder,
> 6-not
> gate and a uln2003 (i think) driving 6 relays, transformer, lm7805,
> electrolytic & decoupling condenser, etc, the power supply.
> 
> - the power on can be done at the transformer o "switching on" only
> the
> protoboard (pic + display). same result
> - there is nothing connected to the relay, the relays don't turn on
> (or
> almost don't click) on power on
> - when the pic start, it switch on / off several times the relays, it
> works fine
> - i don't have a datasheet of the xtal, it's 4MHz generic.
> 
> anyone have some idea of what happen?
> 
> thanks.
> 
> RVP
> 
> 
> 
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