strange problem with 16f877a

[zero2004]

Hi every body

I had bult a pwm application with 16f877a, the circuit work normaly when i tuch the ground wire of dc power supply!!!! , except that it doesn't work, the circuit on a brid bord.

thanks alot for helping me

 

[liquias]

Hi,
You do know you should tie the MCLR pin (using say a 10k resistor) to the +5 rail ?

 

[zero2004]

Hi liquias

I connect it with 10k resister well

 

[Nikunj Tanna]

Hi,

The problem is surely of hardware. Recheck all the connections on bread board. Any of the loose connection can cause this.

NIKS

 

[zero2004]

Hi

I suspect that the problems is in power supply unit, there is a harmonics on dc that affect to the pic, any suggestion for good and reliable dc circuits

thanks

 

[s_cihan_tek]

Most probably a power supply problem. Try turning off the brown-out reset and see if there will be any change.

 

[Tahmid]

Hi,
Place decoupling caps (0.1uF) from the PIC supply pins to ground as well as an electrolytic 10uF as close to the PIC as possible and turn off the BOR.
Hope this helps.
Tahmid.

 

[zero2004]

Hi every body

thanks for your replays, but the problem still exists

thanks again