In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

Ray,

"hammering" an LED on and off w/o any delay from a 50 MHz-clocked SX really does nothing - the LED won't even "glow" because it is too slow to follow the state changes (due to its internal "parasitic capacity") (see the very first sample in my book).

Hard to believe that your board has a failure but you never know... After making sure that you really use a 50 MHz resonator, pull the resonator, and have an Ohm-Meter handy. The center pin of the resonator socket should be contacted to ground (the Ohm-Meter should read almost zero when you touch this center pin, and the center pin of the voltage regulator IC). The meter should also read almost zero when you touch the SX pin 27 (OSC1), and the corresponding pin of the resonator socket. The same should be true when you touch SX pin 26 (OSC2), and the other outer resonator socket pin. You may also verify that the two outer resonator socket pins don't have a short to ground (Vss), or a short between each other.

While you have the ohm-meter handy, it might be an idea to measure the resistance between SX pin 28 (/MCLR) and SX pin 2 (Vdd). You should measure some value between 0 and 10 kOhms - higher values indicate that the /MCLR pin is not properly pulled up to Vdd.

Yes, I know - this is all guesswork but - as we say in German "auch ein blindes Huhn findet manchmal ein Korn" - "even a blind chicken sometimes picks up a corn" - maybe, this helps... :-) .

Merry Christmas, Happy Hannukah, Great Holiday to you, and all the other forum members!

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