NANO100: MCU Sine wave generator - using MCU DAC(Look up table with adjustable amplitude)

1.Generate sample point use octave.

	x = 0 : pi/64 : 2*pi;
	y = 0.5*(sin(x)+1);
	plot(y);

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2.Create look up table.use const to store look up table in ROM for less latency.

	#define SINE_LUT_SIZE (127)
	const float sine_lut[SINE_LUT_SIZE] =
	{
	0.500, 0.524, 0.549, 0.573, 0.597, 0.621, 0.645 ,0.664 ,0.694 ,0.718 ,0.730 ,0.755 ,0.779 ,0.795 ,0.810,
	0.835, 0.853, 0.870 ,0.881 ,0.900, 0.915, 0.928, 0.940, 0.951, 0.961, 0.970, 0.978, 0.985, 0.990, 0.994,
	0.997, 0.999, 1.000, 0.999, 0.997, 0.994, 0.990, 0.985, 0.978, 0.970, 0.961, 0.951, 0.940, 0.928, 0.915,
	0.901, 0.886, 0.870, 0.853, 0.835, 0.817, 0.797, 0.777, 0.757, 0.735, 0.713, 0.691, 0.668, 0.645, 0.621,
	0.597, 0.573, 0.549, 0.524, 0.500, 0.475, 0.450, 0.426, 0.402, 0.378, 0.354, 0.331, 0.308, 0.286, 0.264,
	0.242, 0.222, 0.202, 0.182, 0.164, 0.146, 0.129, 0.113, 0.098, 0.084, 0.071, 0.059, 0.048, 0.038, 0.029,
	0.021, 0.014, 0.009, 0.005, 0.002, 0.000, 0.000, 0.000, 0.002, 0.005, 0.009, 0.014, 0.021, 0.029, 0.038,
	0.048, 0.059, 0.071, 0.084, 0.098, 0.113, 0.129, 0.146, 0.164, 0.182, 0.202, 0.222, 0.242, 0.264, 0.286,
	0.308, 0.331, 0.354, 0.378, 0.402, 0.426, 0.450
	};

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3.Scale to real data function (for 12 bits DAC the max value is 4096)

	#define AMPLITUDE (4000.0)
	#define SINE_SCALE(x) (AMPLITUDE*(x))
	uint32_t index0 = 0;
	DAC_WRITE_DATA(DAC, 0, SINE_SCALE(sine_lut[index0]));

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