How to determine whether PIC 16F872 is dead?

[scdoro]

Hi,

1)Would like to check with u guys how to determine if a chip is dead? Is there a way to check ? Cuz for my chip, It still can be programmed but can't run though my cct is simple n correct.

2) If the chip is dead, would i still get the crystal to oscillate ?
Thanks

 

[IanP]

pic 16f872

Write a simple code which will assert L and H on certain pins .. as simple as possible and program your chip. Try to run it and check if it executes the code ..

Crystal can still oscillate and other blocks of the chip can be faulty ..

 

[scdoro]

16f872 clock

Hi, if cystal can't oscillate, does that mean even if other block of the chip is all rite , it still can't excute ?

 

[rkodaira]

16f872-1

Hi !

If you do not know what component is not working (the PIC or the crystal), you have some options:

1) Try a new 16F872, burn the same hex and replace the old PIC (check and verify the hex codes programmed). If it works, your old PIC is bad. If it does not work, the problem should be in your oscillator section (xtal + capacitors).

2) If you don´t have another 16F872, try to use an external clock (a function generator for example or even a simple 555 astable oscillator). If the circuit works, the problem can be your crystal+load capacitors or the gate (inverter) inside the PIC. If it does not work, you are unluck, the PIC is damaged.

3) Replace crystal and capacitors. When soldering, due the overheat, capacitors and crystals can be damaged.

I had an experience with a 4MHz crystal. It oscillates for a while and after some period of time it stops working.

Unfortunatelly, the 16F872 has not an internal oscillator, so you are dependent of external or xtal oscillators.

 

[scdoro]

pic verifies but is not programmed

Hi,
thanks for the advise.
But I am using the ICD2 programmer, and is actually direct soldering through a connector that is connected to my PIC. But the thing is other than i can't get the crystal working, I can't even detect a Vpp of 12 V when programming .. So i suspect that my chip can't even be programmed.
Last time is it able to me programmed but now the programming voltage is 0V which i connect to the PIN 1 of MCLR_ / Vpp.
1)May I know what could cause the Vpp to be 0V.
2)If cystal is not working , can the pic still can be programmed ?
3)If my PIC chip is blank, ( not programmed ) , can the crystal still osciallate when connected to osc1 and osc2 of the PIC ?
Thanks

Added after 21 minutes:

oh yes, to add on the previous posting, when programming, my MPlab actually output a msg to verified that the program is success download to my PIC but i didn't get any Vpp ( programming voltage still 0V) , during the programmming ..
Did anyone know why ? thanks alot

 

[IanP]

circuito pic 16f872

Do you heve the PIC connected as shown on this page?
**broken link removed**
Can you check the on-board +5V supply ..
And have a look at the guidelines; maybe there you can find some hints that will allow you to check your programmer...

 

[Lepidoptera_ece]

pic how to check if the chip is dead

Hi, if cystal can't oscillate, does that mean even if other block of the chip is all rite , it still can't excute ?

if you consider that your connection are all right and still you can't make the crystal to oscillate. there is a big possibilty that your chip is damaged because there is no enough energy to passthrough your crystal and made it able to oscillate, But if in case your crystal is defective it is impossible for the microcontroller to execute, because the machine mainly depend on clock ticks to execute.