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Hello; I have one problem in LPC2138 Proto-Type board . I am able to write a code in its flash memory using flash magic. Hex file is successfully loaded . but after Resetting or in power on mode code is not executed . I used 12 Mhz crystal . I tried LED blinking code.
The capacitive load from the multimeter might make the crystal oscillator fail to operate. But it might also get an oscillator that doesn't run correctly to start generate the expected 12MHz.
Best is to have access to an RF analyzer that can listen to the oscillator without electrical connection. Second best is probably a scope probe in 10:1 mode, after you have calibrated the capacitance using the test output of the oscilloscope.
But notice that it makes a lot of difference which of the two crystal pins you look at. One oscillator on the processor is input and one is output. It's way better to probe the output pin that drives the crystal.
I think NXP names the input pin XTAL1 and the output pin XTAL2 for your processor. That's at least the naming they have for a number of newer chips.
But did you test to modify the code to run the RC oscillator instead? Just to figure out if your troubles are related to the crystal frequency and stability?