Realtime spectrum analyzer. Using FFT, linear prediction, or cepstrum smoothing. Version using MEMS microphone and CODEC, named "F746_RealtimeSpectrumAnalyzer_MEMS_Mic" is registered. リアルタイム スペクトル解析器.解析の手法:FFT,線形予測法,ケプストラムによる平滑化の3種類.このプログラムの説明は,CQ出版社のインターフェース誌,2016年4月号に掲載.外付けのマイクまたは他の信号源等を A0 に接続する.線形予測法,ケプストラムは,スペクトル解析の対象を音声信号に想定してパラメータを設定している.MEMS マイクと CODEC を使ったバージョンを "F746_RealtimeSpectrumAnalyzer_MEMS_Mic" として登録.
Dependencies: BSP_DISCO_F746NG BUTTON_GROUP LCD_DISCO_F746NG TS_DISCO_F746NG UIT_FFT_Real mbed
Diff: MyClasses/sampler.hpp
- Revision:
- 0:5c237fdcba23
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MyClasses/sampler.hpp Wed Dec 09 05:05:00 2015 +0000 @@ -0,0 +1,93 @@ +//----------------------------------------------------------- +// Class for sampling input signal +// +// 2015/12/08, Copyright (c) 2015 MIKAMI, Naoki +//----------------------------------------------------------- + +#ifndef F746_SAMPLER_HPP +#define F746_SAMPLER_HPP + +#include "mbed.h" + +namespace Mikami +{ + class Sampler + { + public: + Sampler(PinName pin, Ticker& timer, int nData) + : N_DATA_(nData), aIn_(pin), timer_(timer), + buffer_(new int16_t[nData]) + { + SetParams(false); + inv_ = false; + } + + ~Sampler() { delete[] buffer_; } + + void Execute() + { + int16_t xn = Read(); + if (!trigger_) + { + // Detect rising edge + if ((xn > (xnM1_+512)) && (xn > 2048)) + trigger_ = true; + else + xnM1_ = xn; + return; + } + + buffer_[count_] = Read(); // Read from A0 + + if (++count_ >= N_DATA_) + { + SetParams(true); // Permits spectrum analysis + timer_.detach(); // Disable timer interrupt + } + } + + void ClearCount() { count_ = 0; } + + bool Filled() { return filled_; } + + void Restart() { filled_ = false; } + + bool InvertEnable(bool onOff) + { + inv_ = onOff; + return onOff; + } + + // Get sampled data + int16_t* Get() { return buffer_; } + + private: + const int N_DATA_; // number of 1 frame data + + AnalogIn aIn_; // Object of ADC + Ticker& timer_; // Reference for object of Ticker + + bool trigger_; + bool filled_; + bool inv_; + int count_; + int16_t xnM1_; + + int16_t* buffer_; // for sampled data + + int16_t Read() + { + return inv_ ? 32767 - aIn_.read_u16() + : aIn_.read_u16() - 32767; + } + + void SetParams(bool tf) + { + trigger_ = false; + count_ = 0; + xnM1_ = 32767; + filled_ = tf; + } + }; +} +#endif // F746_SAMPLER_HPP