Arduino和MP3 Shield不能与从Pieszo传感器接收的信息同时工作

Question

我正在编写的程序基本上可以让一个人用一个Pieszo传感器连接到他们的鞋子底部来运行/步进，并且相同的bpm相应的轨道将通过连接到Arduino上的MP3shield的小型扬声器播放。这是一个更大概念的原型。

以下是我到目前为止：

// libraries
#include <SPI.h>
#include <SdFat.h>
#include <SdFatUtil.h>
#include <SFEMP3Shield.h>
#include <SimpleTimer.h>

int knockSensor = 0;
int MINIMUM = 520;
int MAXIMUM = 530;
int counter = 0;
int comparativeBPM;

SdFat sd;

SFEMP3Shield MP3player;

SimpleTimer timer;

String trackLibrary[30] = {track001.mp3, track002.mp3, track003.mp3, track004.mp3, track005.mp3, track006.mp3, track007.mp3, track008.mp3, track009.mp3, track010.mp3, track011.mp3, track012.mp3, track013.mp3, track014.mp3, track015.mp3, track016.mp3, track017.mp3, track018.mp3, track019.mp3, track020.mp3, track021.mp3, track022.mp3, track023.mp3, track024.mp3, track25.mp3, track026.mp3, track027.mp3, track028.mp3, track029.mp3, track030.mp3};
//bpms increases by 1 starting with 151 in the track library above so 151-180

void setup() {
  Serial.begin(9600);
  timer.setInterval(1000, ticker);

  if(!sd.begin(9, SPI_HALF_SPEED)) sd.initErrorHalt();
  if (!sd.chdir("/")) sd.errorHalt("sd.chdir");

  MP3player.begin();
  MP3player.setVolume(10,10);
}

void loop() {
  timer.run();
  if (analogRead(knockSensor) >= MINIMUM && analogRead(knockSensor) <= MAXIMUM) { //if knock is between maximum and minimum threshold
    Serial.println("Step detected"); //print when step detected
    counter = knockSensor++; //increment counter every time step detected
    Serial.println(counter); //print counter value to test
  }
  if (timer == 60000) {
    comparativeBPM = (counter/60)*3; // divide counter by 60s to get BPM and multply by 3 to get average bpm
      if (comparativeBPM >= 151) {
        MP3player.playTrack(track001.mp3);
      }
      if (comparativeBPM == 152) {
        MP3player.playTrack(track002.mp3);
      }
      if (comparativeBPM == 153) {
        MP3player.playTrack(track003.mp3);
      }
      if (comparativeBPM == 154) {
        MP3player.playTrack(track004.mp3);
      }
      if (comparativeBPM == 155) {
        MP3player.playTrack(track005.mp3);
      }
      if (comparativeBPM == 156) {
        MP3player.playTrack(track006.mp3);
      }
      if (comparativeBPM == 157) {
        MP3player.playTrack(track007.mp3);
      }
      if (comparativeBPM == 158) {
        MP3player.playTrack(track008.mp3);
      }
      if (comparativeBPM == 159) {
        MP3player.playTrack(track009.mp3);
      }
      if (comparativeBPM == 160) {
        MP3player.playTrack(track010.mp3);
      }
      if (comparativeBPM == 161) {
        MP3player.playTrack(track011.mp3);
      }
      if (comparativeBPM == 162) {
        MP3player.playTrack(track012.mp3);
      }
      if (comparativeBPM == 163) {
        MP3player.playTrack(track013.mp3);
      }
      if (comparativeBPM == 164) {
        MP3player.playTrack(track014.mp3);
      }
      if (comparativeBPM == 165) {
        MP3player.playTrack(track015.mp3);
      }
      if (comparativeBPM == 166) {
        MP3player.playTrack(track016.mp3);
      }
      if (comparativeBPM == 167) {
        MP3player.playTrack(track017.mp3);
      }
      if (comparativeBPM == 168) {
        MP3player.playTrack(track018.mp3);
      }
      if (comparativeBPM == 169) {
        MP3player.playTrack(track019.mp3);
      }
      if (comparativeBPM == 170) {
        MP3player.playTrack(track020.mp3);
      }
      if (comparativeBPM == 171) {
        MP3player.playTrack(track021.mp3);
      }
      if (comparativeBPM == 172) {
        MP3player.playTrack(track022.mp3);
      }
      if (comparativeBPM == 173) {
        MP3player.playTrack(track023.mp3);
      }
      if (comparativeBPM == 174) {
        MP3player.playTrack(track024.mp3);
      }
      if (comparativeBPM == 175) {
        MP3player.playTrack(track025.mp3);
      }
      if (comparativeBPM == 176) {
        MP3player.playTrack(track026.mp3);
      }
      if (comparativeBPM == 177) {
        MP3player.playTrack(track027.mp3);
      }
      if (comparativeBPM == 178) {
        MP3player.playTrack(track028.mp3);
      }
      if (comparativeBPM == 179) {
        MP3player.playTrack(track029.mp3);
      }
      if (comparativeBPM == 180) {
        MP3player.playTrack(track030.mp3);
      }
    }
    timer.restartTimer(timer);
  } 
}

void ticker() {
  Serial.print("Time (s): ");
  Serial.println(millis()/1000);
}

如果有人知道这是如何运作的，那么任何帮助都会非常感激。我正在使用的MP3屏蔽是一个SparkfunMP3屏蔽，并在这里附带它自己的参考库https://learn.sparkfun.com/tutorials/mp3-player-shield-hookup

这应该有用，但我对文档知之甚少，无法弄清楚为什么这不起作用！请帮忙