Question

/*
fft_adc_serial.pde
guest openmusiclabs.com 7.7.14
example sketch for testing the fft library.
it takes in data on ADC0 (Analog0) and processes them
with the fft. the data is sent out over the serial
port at 115.2kb.
*/

#define LOG_OUT 1 // use the log output function
#define FFT_N 256 // set to 256 point fft

#include <FFT.h> // include the library

unsigned long time;

void setup() {
  Serial.begin(115200); // use the serial port
  TIMSK0 = 0; // turn off timer0 for lower jitter
  ADCSRA = 0xe5; // set the adc to free running mode
  ADMUX = 0x40; // use adc0
  DIDR0 = 0x01; // turn off the digital input for adc0
}

void loop() {
  while(1) { // reduces jitter
    cli();  // UDRE interrupt slows this way down on arduino1.0
    for (int i = 0 ; i < 512 ; i += 2) { // save 256 samples
      while(!(ADCSRA & 0x10)); // wait for adc to be ready
      ADCSRA = 0xf5; // restart adc
      byte m = ADCL; // fetch adc data
      byte j = ADCH;
      int k = (j << 8) | m; // form into an int
      k -= 0x0200; // form into a signed int
      k <<= 6; // form into a 16b signed int
      fft_input[i] = k; // put real data into even bins
      Serial.print("input ");
      Serial.print(i);
      Seirla.print(" = ");
      Serial.println(k);
      fft_input[i+1] = 0; // set odd bins to 0
    }
    fft_window(); // window the data for better frequency response
    fft_reorder(); // reorder the data before doing the fft
    fft_run(); // process the data in the fft
    fft_mag_log(); // take the output of the fft
    sei();
    Serial.println("start");
    for (byte i = 0 ; i < FFT_N/2 ; i++) { 
      Serial.print("\t output");
      Serial.print(i);
      Serial.println(fft_log_out[i]); // send out the data
    }
  }
}

我使用这个FFT示例代码进行FFT

cli();  // UDRE interrupt slows this way down on arduino1.0
        for (int i = 0 ; i < 512 ; i += 2) { // save 256 samples
          while(!(ADCSRA & 0x10)); // wait for adc to be ready
          ADCSRA = 0xf5; // restart adc
          byte m = ADCL; // fetch adc data
          byte j = ADCH;
          int k = (j << 8) | m; // form into an int
          k -= 0x0200; // form into a signed int
          k <<= 6; // form into a 16b signed int
          fft_input[i] = k; // put real data into even bins
          Serial.print("input ");
          Serial.print(i);
          Seirla.print(" = ");
          Serial.println(k);
          fft_input[i+1] = 0; // set odd bins to 0
        }

在此输入部分输入时间段多少？

Theres没有延迟（）;此示例中的函数

 while(!(ADCSRA & 0x10)); // wait for adc to be ready

这行像delay（）函数一样工作吗？这个函数等待Analog0多长时间？

Answer 1

采样率在wiring.c中设置： https://code.google.com/p/arduino/source/browse/trunk/hardware/cores/arduino/wiring.c?r=565#210

因此，在16mHz的arduino上，最大采样率为9600hz，但实际采样率很大程度上取决于转换之间的延迟。由于您的波特率非常高，并且您没有进行大量计算，因此它应该在9600hz旁边。

更新：这里有一个更准确的答案：https://arduino.stackexchange.com/a/701

如何知道Arduino采样率

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