I guess my PIC is either busted or there is a need of Vdd to Vss decoupling. As my circuit suddenly drops to voltage levels of zero as soon as i place PIC. though programmer does not show that there is any error with PIC. Program burns correctly. Last Test program that I did, ran correctly. Though I think the main reason for these voltage drops is PIC. Any reason why this happens?
my programmer is entirely different from circuit. i use it just to program the device. so i guess it works properly. error lies in the board that I'm using.
Where are you measuring the supply, at the PIC supply pins, or, at the supply input to the board?
If the supply is OK where it comes on to the board, look for bad joints on the board between the supply and the PIC.
though programmer does not show that there is any error with PIC. Program burns correctly. Last Test program that I did, ran correctly. Though I think the main reason for these voltage drops is PIC. Any reason why this happens?
Could it be that your program is driving outputs which are causing a power short?
For example, a pin is configured as an output and turned on, but the pin is connected to the 0v line.
supply is a battery. it is pretty fine. gives 7.5 volts. but sooner i place the pic, all the levels that are fed with the output of regulator(which gives 4.88V), start to get to 0v. not only that all levels turn to zero but the regulator input i.e. power from battery also gets altered & starts showing value 4V. also terminals of battery that are connected to board also get to voltage level of 4V.
Yes it was a 9V battery. though this circuit draws that much current that it got dropped down to 7.5 in total work of just half an hour. I'm sure there is a short. Cannot figure out where it is though.
Try with a fresh battery. Does the PIC get noticeably warm? If it does, that suggests either it's outputs are trying to draw too much current or it has an internal high-current fault path.
What loads is the PIC driving? Do you have current-limiting resistors for the loads?
digital multiplexer & LCD are the loads that i'm driving. I thought of putting 10K in series with the port pins. But is such a pull-up necessary; as for digital circuits, I guess Controller can source current that is enough. I haven't added certain high-power loads like motore to circuit yet. PIC doesn't get warm.