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µVISION DEBUGGER: SINE WAVE SIGNAL FUNCTIONInformation in this article applies to:
QUESTIONIs it possible to create a sine wave input on the analog inputs using the signal functions in the µVision Debugger? ANSWERYes. The following signal function does just that. signal void analog0_sine (float limit) { float i; float i2; float sine; printf ("Analog0_sine (%f) entered.\n", limit); while (1) { /* forever */ /* SIN swings from 1 to 1 so... adjust it to swing from 0 to 1 */ /* This is a Taylor series that calculates SIN */ /* i is the angle where 1.0 = pi/2 and 1.0 = +pi/2 */ for (i = 1.0; i < 1.0; i += 0.01) { i2 = i * i; sine = i * (1.5707963  i2*(0.6459640  i2*(0.0796926  i2*(0.0046817  i2*(0.0001604))))); /* printf ("SIN(%4f) = %6f\n", i * 90.0, sine); */ ain0 = ((sine + 1.0) / 2.0) * limit; twatch (2000000); } for (i = 1.0; i > 1.0; i = 0.01) { i2 = i * i; sine = i * (1.5707963  i2*(0.6459640  i2*(0.0796926  i2*(0.0046817  i2*(0.0001604))))); /* printf ("SIN(%4f) = %6f\n", i * 90.0, sine); */ ain0 = ((sine + 1.0) / 2.0) * limit; twatch (2000000); } } } This signal function uses a Taylor series to calculate the sin for pi/2 to pi/2. The sin (which normally ranges from 1.0 to 1.0) is normalized to a range of 0.0 to 1.0 and this is used to calculate the input voltage (by multiplying by a maximum limit). To start this signal function, you must invoke it from the command line in the debugger. For example: analog0_sine (2.500) starts the sine wave function which will generate a sine wave on analog input 0 ranging from 0.0 volts to 2.5 volts. You will need to change the increment and decrement in the for i loops to change the number of steps. You must change the number of clock cycles to delay for each step in the twatch calls. SEE ALSOLast Reviewed: Monday, June 28, 2004  

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