I'm having an issue with PIC16F877A where it starts up;
after significant amount of time, maybe 15 seconds, when it has been powered down for few minutes.
after about 0.5 seconds when powered off while it's running, then powering it on again quickly.
I tried with both PICkit 2 and regulated 5V and tried removing the load capacitors which are 33pF with 20MHz crystal.
What could be causing inconsistent start up time?
Here is my circuit diagram, all I do is connect the PICkit 2 header directly to the corresponding pins on 16F877A.
I've read that capacitors connected to the crystal oscillator determines the start up time but I don't think that is causing this.
Regardless I attached the screenshot.
Yes, I'm using Proteus. It works when simulating as expected but on hardware, as stated in the original post,
there's an unknown delay and inconsistent start up time before PIC starts executing the instructions.
I will follow your advice and make changes to the circuit.
Just out of curiosity, if MCLR is not connected to anything wouldn't it mean it's LOW or 0V?
Any particular reason for additional resistor for MCLR?
Thanks, I didn't know specifically about that part number.
A useful tip for any PIC is to look for the 'minimum connections' diagram for the device (if there is one), usually in an early section of the datasheet. That will show which capacitors and resistors are required.