void FREQOUT (int  pin, int milliseconds, int  freq1, int freq2 );

Generate a sine-wave signal on pin for milliseconds.
A single frequency or mixed dual frequncy tone may be generated.
The IO direction of the pin will be set to output.
The output pin might be connected to a speaker or audio amplifier.

    printStr("2 Hz on LED for 2 seconds\n");
    FREQOUT (15,2000,2,0);