Arduino wont open SD card file

this first time using sd card reader. need log distance measurements hc-sr04 wont open file on sd card. suggestions? ill upload code.

code: [select]


#include <newping.h>
#include <sd.h>
#include <spi.h>

#define trigger_pin 6
#define echo_pin 7
#define max_distance 200
#define pingspeed 1000
newping sonar(6,7,65);

#define chipselect 4
file myfile;

void setup() {
  serial.begin(115200);
  serial.println("initializing sd card");
 
  if (!sd.begin(4)) {
    serial.println("it aint working");
    return;
  }
  serial.println("initialization works");
  pinmode(10,output);
 

}

void loop() {
  ping();
  delay(5000);
  sdcard();
 
 

}

void ping(){
 delay(50);
 int us=sonar.ping();
 serial.print("ping: ");
 serial.print(us/us_roundtrip_cm);
 serial.println("cm");


 }

 void sdcard() {
  myfile = sd.open("ultra.txt", file_write);

  if (myfile){
    int us=sonar.ping();
    myfile.println(us/us_roundtrip_cm);
    myfile.close();
  }
  else {
    serial.println("error in opening file");
  }
 
 }


i found problem: using 32gb sd card , arduino can't write big of card apparently.

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