cn0540_adi_fft.h

00001 /******************************************************************************
00002  *Copyright (c)2020 Analog Devices, Inc.  
00003  *
00004  * Licensed under the 2020-04-27-CN0540EC License(the "License");
00005  * you may not use this file except in compliance with the License.
00006  *
00007  ****************************************************************************/
00008 
00009 #ifndef CN0540_ADI_FFT_H_
00010 #define CN0540_ADI_FFT_H_
00011 
00012 #include "stdint.h"
00013 #include "arm_math.h"
00014 #include "stdbool.h"
00015 
00016 /**
00017  ******************************************************************************************************************************************************************
00018  ******************************************************************************************************************************************************************
00019  * 
00020  *          MACROS AND CONSTANT DEFINITIONS
00021  */
00022 
00023 #define N_BITS                  24                              // Define resolution of the ADC
00024 
00025 
00026 #define SQRT_2                  sqrt(2)
00027 #define ADC_FULL_SCALE          (1 << N_BITS)                   // Full scale of the ADC depends on the N_BITS macro, for 24-bit ADC, ADC_FULL_SCALE = 16777216
00028 #define ADC_ZERO_SCALE          (1 << (N_BITS - 1))             // Zero scale of the ADC depends on the N_BITS macro, for 24-bit ADC, ADC_ZERO_SCALE = 8388608
00029 
00030 #define DC_BINS                 10                              // Ignoring certain amount of DC bins for for noise and other calculations
00031 #define FUND_BINS               10                              // Power spread of the fundamental, 10 bins from either side of the fundamental
00032 #define HARM_BINS               3                               // Power spread of the harmonic, 10 bins from either side of the harmonic
00033 
00034 
00035 /**
00036  ******************************************************************************************************************************************************************
00037  ******************************************************************************************************************************************************************
00038  * 
00039  *          TYPES DECLARATIONS
00040  */
00041 
00042 enum fft_windowing_type
00043 {
00044     BLACKMAN_HARRIS_7TERM,
00045     RECTANGULAR
00046 };
00047 
00048 struct fft_entry                                    // Structure carying all the necessary data, the FFT work with
00049 {
00050     float   vref;
00051     uint16_t    mclk;
00052     float   bin_width;
00053     uint32_t    sample_rate;                        // Sample rate based on MCLK, MCLK_DIV and Digital filter settings
00054     uint16_t    fft_length;                         // Length of fft = sample_count / 2
00055     int32_t     codes[4096];                        // Codes in range 0 +/- ZERO SCALE
00056     int32_t     zero_scale_codes[4096];             // Codes shifted up by ZERO SCALE - range ZERO SCALE +/- ZERO SCALE
00057     float   voltage[4096];                      // Voltage before windowing
00058     float   fft_magnitude[2048];                // Maximum length of FFT magnitude supported by the on-chip DSP = 4096 samples
00059     float   fft_magnitude_corrected[2048];      // Maginute with windowing correction
00060     float   fft_dB[2048];                       // dB fro plot
00061     float   fft_input[8192];                    // Maximum length of FFT input array supporred by the on-chip DSP = 4096 Real + 4096 Imaginary samples
00062     float   noise_bins[2048];                   // FFT bins excluding DC, fundamental and Harmonics
00063     enum fft_windowing_type window;                 // WIndow type
00064     bool        fft_done;
00065 };
00066 
00067 struct fft_measurements                             // Structure carying all the FFT measurements
00068 {
00069     float   harmonics_power[6];                 // Harmonics, including their power leakage
00070     float   harmonics_mag_dbfs[6];              // Harmonic magnitudes for THD
00071     uint16_t    harmonics_freq[6];                  // Harmonic frequencies for THD
00072     float   fundamental;                        // Fundamental in volts
00073     float   pk_spurious_noise;                  // Peak spurious noise (amplitude)
00074     uint16_t    pk_spurious_freq;                   // Peak Spurious Frequency
00075     float   THD;                                // Total Harmonic Distortion
00076     float   SNR;                                // Signal to Noise Ratio
00077     float   DR;                                 // Dynamic Range
00078     float   SINAD;                              // Signal to Noise And Distortion ratio
00079     float   SFDR_dbc;                           // Spurious Free Dynamic Range, dBc
00080     float   SFDR_dbfs;                          // Spurious Free Dynamic Range, dbFS
00081     float   ENOB;                               // ENOB - Effective Number Of Bits
00082     float   RMS_noise;                          // same as transition noise
00083     float   average_bin_noise;
00084     float   max_amplitude;
00085     float   min_amplitude;
00086     float   pk_pk_amplitude;
00087     float   DC;
00088     float   transition_noise;
00089     uint32_t    max_amplitude_LSB;
00090     uint32_t    min_amplitude_LSB;
00091     uint32_t    pk_pk_amplitude_LSB;
00092     int32_t     DC_LSB;
00093     float   transition_noise_LSB;
00094 };
00095 
00096 /**
00097  ******************************************************************************************************************************************************************
00098  ******************************************************************************************************************************************************************
00099  * 
00100  *          FUNCTION DECLARATIONS
00101  */
00102 
00103 int32_t FFT_init_params(struct fft_entry **fft_entry_init, struct fft_measurements **fft_meas);
00104 void perform_FFT(uint32_t *data, struct fft_entry *fft_data, struct fft_measurements *fft_meas, uint32_t sample_rate);
00105 void FFT_init(uint16_t sample_count, struct fft_entry *fft_data);
00106 void update_FFT_enviroment(uint16_t reference, uint16_t master_clock, uint16_t sampling_rate, struct fft_entry *fft_data);
00107 void static FFT_maginutde_do_dB(struct fft_entry *fft_data, double sum);
00108 void static FFT_calculate_THD(struct fft_entry *fft_data, struct fft_measurements *fft_meas);
00109 void static FFT_calculate_noise(struct fft_entry *fft_data, struct fft_measurements *fft_meas);
00110 float static dbfs_to_volts(float vref, float value);
00111 void static FFT_windowing(struct fft_entry *fft_data, double *sum);
00112 void static FFT_waveform_stat(struct fft_entry *fft_data, struct fft_measurements *fft_meas);
00113 #endif // !ADI_FFT_H_
00114