如何知道Arduino采样率

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
    }
  }
}

我将此 FFT 示例代码用于 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
        }

在这个输入部分输入多少时间段？

没有延迟();本例中的函数

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

这条线像 delay() 函数一样工作？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 上，arduino 的最大采样率为 9600hz，但实际采样率在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不需要进行大量计算，因此它应该接近 9600hz。

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

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