Hi All, I am facing a problem in a project that i am building using PIC16F877A, the problem is that my PIC uC won't start its operation until I press the reset button twice or thrice...
My circuit simulates perfectly in proteus but it is not showing the desired output on the vero board.. I have double checked all the connections and they are all good....Need help!
Thanking you in anticipation.View attachment 82747
Change the MCLR pullup resistor to 10k.
Use 0.1uF capacitors across both VDD and VSS lines. Ensure you've connected both VDD and VSS lines properly.
You may also want to add a capacitor from MCLR pin to ground if the problem persists. Use a capacitor with capacitance between 0.01uF and 0.1uF.
Hope this helps.
Tahmid.
Hello Tahmid,
I don't think so that connecting a capacitor across Vcc a Vdd might have any effect on MCLR ['reset'] pin. Connecting a capacitor across Vss and Vdd only provide exact 5 volts to MCU (Microcontroller) without nay noise or spikes.
one of the short comings of faked chips lies in the operating speed claimed by the original vendor...so i advice u go down to a lower clock "crystal value". i hav had bad times in terms of crystal value with the PIC16F877A MCU from microchip runing at such crystal value and above and to be sure my code is ok i back tested with F84A and 873A pics and voila! it worked.... also try grounding the cystals body with a wire i beliv this shud help........sequel
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