 
 #include "LCD4884.h"
 
+#include <SD.h>
+
 #define GPRMC "$GPRMC" // 推荐最小定位信息
 #define GPVTG "$GPVTG" // 地面速度信息
 #define GPGGA "$GPGGA" // 获取海拔高度

boolean readGPS() {
    String sub = readLine();
    if(sub.length()) {
      Serial.println(sub);
      Serial.println("-------------------------------------------");
      int split = sub.indexOf(',');    
      String field = sub.substring(0,split);
      if(field.equals(GPRMC)) {


  lcd.init();
  lcd.clear();
  
  if (!SD.begin(SD_CS)) {
//    Serial.println("initialization failed!");
    return;
  }
//  Serial.println("initialization done.");
  
  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  
}

void loop(){ 
