Dear All,
           I developed a basic board to help people learn PIC microcontroller programming. The board is based on the PIC 16F877A microcontroller and I have enclosed a picture of the board at the following page: http://mechatronicscraze.wordpress.com/2010/02/08/the-board-has-been-populated-and-it-is-ready/
      The board was tested and the results were successful. I ordered for another set of 10 boards and populated four of them. I faced a weird problem with three boards. I identified that in one of the boards, the board didn't work because of a low quality tact switch that kept my MCLR pin low. I avoided soldering the tact switches in the other two boards. In both these boards, I see that the MCLR pin is high and the voltage is 5V between pin 11 and 12 of 16F877A. However, both the boards were not functional. On replacement of the crystals and capacitors, one of the board has started functioning. The other board is not functional even after replacing three sets of capacitors and crystals of both XT and HS frequencies. I have taken care that I have set the correct fuse bit before I build my program. (XT or HS at address 2007 and low voltage programming was disabled)
           The problem is that I don't have an access to oscilloscope and I am not able to identify the problem behind the board. I am very sure that someone might have faced this problem. I would be glad if anyone could offer me assistance for the same.

Sairam


      
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