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[moved] pickit 2 and 16f877a not working after burn

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Junior Member level 3
Oct 20, 2010
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Mandaluyong, Philippines
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i burned blinking hex file to my pic16f877a successfully using pickit2. using different breadboard with 20mhz xtal, 10k pull up resistor and two 33uf capacitor (typical setup).. it does not blink.. im lost i dont know why its not working.. i downloaded different hex file compatible but still not working.. did i missed something?

did i missed something?

Most likely, however it is difficult to render any meaningful advice, without first examining your source code and a schematic of the design.

If all you have is a HEX file, with no accompanying source code, the reasons for the issues you face are numerous, as you've relied on the judgement and skills of the person whom originally compiled the code.

Some possible sources of the issue are improperly set configuration bits for your particular implementation or perhaps the HEX file does not include any configuration bit settings.

The original source code may have been written for a particular system clock frequency or a particular source of the system clock.

Also, you should be aware the actual process of programming a PIC microcontroller does not require a oscillator/system clock to be implemented, as the clock source originates from the programmer device. Even though you may have verified that the contents of the HEX have been successfully downloaded into the microcontroller, it does not guarantee it will function as expected.

Therefore to assist you further, you will need to elaborate on the specifics of your design, its purpose, which PIC microcontroller you are utilizing, posting or uploading a detailed schematic of the design and the source code. Barring that and the source code is not available, then uploading the HEX may provide some insight in the source of the issues.


After seeing that:
i...breadboard with 20mhz xtal...and two 33uf capacitor (typical setup).....
Just a quick question:
What is the value of the capacitors you are using?
The 33pF may be out of spec for your crystal, or requiring a series Resistor.
Try 22pF in stead.

WDT resetting PIC ? MCLR if enabled pulled high to 5V using a 10k resistor ?

attached is my circuit

i burned the typical blink hex from different ide ...mplab, proton basic with the appropriate settings for crystal 20mhz and pic model... so my hex is good..

i think there is something to do with configuration word/bit... i dont know whats the setup for it.. right now my setup is "2F02"

both PIC16F84A and PIC16F877A successfully burnt but not blinking
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Your oscillator circuit is far from the PIC and maybe this is causing the problem. Also there is no 100 nF and 10UF capacitors across VDD and VSS pins of PIC and close to PIC.

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