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31 lines
939 B
C++
31 lines
939 B
C++
/**
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* 5_fir_differentiator.cpp
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* Written by Clyne Sullivan.
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*
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* Does an FIR differentiation on the incoming signal, so that the output is representative of the
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* rate of change of the input.
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* A scaling factor is applied so that the output's form is more clearly visible.
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*/
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adcsample_t *process_data(adcsample_t *samples, unsigned int size)
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{
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constexpr int scaling_factor = 4;
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static adcsample_t output[SIZE];
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static adcsample_t prev = 2048;
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// Compute the first output value using the saved sample.
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output[0] = 2048 + ((samples[0] - prev) * scaling_factor);
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for (unsigned int i = 1; i < size; i++) {
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// Take the rate of change and scale it.
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// 2048 is added as the output should be centered in the voltage range.
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output[i] = 2048 + ((samples[i] - samples[i - 1]) * scaling_factor);
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}
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// Save the last sample for the next iteration.
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prev = samples[size - 1];
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return output;
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}
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