Resonator location with BS2-OEM on a breadboard

[Lev]

Hi:

I have been testing a project using a BS2-OEM module on a breadboard, and it has worked perfectly.· I then replaced the OEM module on the breadboard with·discrete OEM components (interpreter, EEPROM, and 20 MHz resonator), closely following the Parallax schematic.· I have been unable to get·the·LCD output (19,200 baud) and·74HC595 shift register to function.· I have checked the wiring several times, and cannot find any mistakes.· Is it possible that the breadboard is causing problems with the·resonator signal?··The resonator is·located close to the interpreter, and connected with 0.5 inch long jumpers laid flat to the breadboard.

Thanks,
Rich

[Chris Savage]

Rich,

The capacitance in breadboards has been known to cause problems with higher speed signals, however in this case I’m not sure that is your issue. You refer to specific problems, but does anything else work? Does the display wok at lower baud rates?

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Chris Savage
Parallax Tech Support

[Lev]

Hi Chris:

Sound output to the LM386 worked, and the inputs all worked. I just stuck the BS2-OEM module back in, rearranged the wiring, and it works fine like it did before. Hmmm. I'll go back to the discrete components and rewire again, then test the LCD at a lower baud as you suggested.

Thanks,
Rich