如何在arduino中从SD卡创建变量

Question

I have saved a number onto a sd card in a file called CONFIG.BAT, it is a telephone number and is in the format of "+441234567890", in the serial monitor I can print it out using

  myFile = SD.open("CONFIG.DAT");

  if (myFile) {

Serial.println("CONFIG.DAT:");

// read from the file until there's nothing else in it:
while (myFile.available()) {

      Serial.write(myFile.read());

}

And I get this responce

Initializing SD card...initialization done.
CONFIG.DAT:
+441234567890

What I want to do is put this number into a variable "telNo", I have tried to use

telNo = (myFile.read());

The response I get is

Initializing SD card...initialization done.
CONFIG.DAT: 
10

I'm not sure what this "10" signifies.

I have also tried "concat"

while (myFile.available()) {

        number.concat(myFile.read());      

}

The response I get is the Decimal code for the number with some numbers on the end I don't understand

Initializing SD card...initialization done.
CONFIG.DAT: 
48555653515353555354561310

The last four numbers (1310) I don't understand

What I'm looking to achieve is "telNo = the telephone number in the CONFIG.DAT file, so if any one could help I would appreciate it

Here is my full Sketch

#include <SoftwareSerial.h>
//#include <SD.h>
#define SD_CS_PIN SS
#include <SPI.h>
#include "SdFat.h"

SdFat SD;

File myFile;

//SIM800 TX is connected to Arduino D8
#define SIM800_TX_PIN 8

//SIM800 RX is connected to Arduino D7
#define SIM800_RX_PIN 7

//Create software serial object to communicate with SIM800
SoftwareSerial serialSIM800(SIM800_TX_PIN,SIM800_RX_PIN);


//const int ledPin3 = 11;//Define the Bluetooth led pin
const int ledPin2 = 2;//Define the interupt pin to signify bluetooth connect or disconnect

String readString = "";
String telNoString = "";
String number = "";

volatile int ledonState = 0;
int lastLedonState = 0;


const int thresholdvalue=680;//The threshold to turn the led on


void setup() {
  pinMode (ledPin2, INPUT);//set input for interupt pin
  //pinMode (ledPin3, OUTPUT);//set output for bluetooth pin

  attachInterrupt(0, pin_ISR, CHANGE);

  Serial.begin(9600);

  while(!Serial);

  //Being serial communication witj Arduino and SIM800
  serialSIM800.begin(9600);
  delay(1000);

  SysCall::yield();

  Serial.println("Setup Complete!");

}


void pin_ISR() {
  ledonState = digitalRead(ledPin2);

if (ledonState != lastLedonState) {

  if (ledonState == HIGH) {
        //digitalWrite(ledPin3, HIGH);//turn led on
            Serial.println("HC-05 is now connected");
            //Serial.println();
      }else{
         //digitalWrite(ledPin3, LOW);//turn led off
             Serial.println("HC-05 is now Disconnected");
             //Serial.println();
  }
lastLedonState = ledonState;
}
}


void sound_detect(){

  int sensorValue = analogRead(A0);//use A0 to read the electrical signal

  if(sensorValue > thresholdvalue) {

//  digitalWrite(ledPin1,HIGH);//if the value read from A0 is larger than 400,then light the LED
//  delay(10);
//  digitalWrite(ledPin1,LOW);

 Serial.print("Initializing SD card...");

  pinMode(10, OUTPUT);

  if (!SD.begin(SD_CS_PIN)) {
    Serial.println("initialization failed!");
    return;
  }

  Serial.println("initialization done.");  

  if (!SD.exists("CONFIG.DAT")) {

    Serial.println("No Number Exists! Please go to Setup Device to add Number for Alert");

  }else{

  // open the file for reading:
  myFile = SD.open("CONFIG.DAT");

  if (myFile) {

    Serial.println("CONFIG.DAT:");

    // read from the file until there's nothing else in it:
    while (myFile.available()) {

            number.concat(myFile.read());      
          //number = (myFile.read());
          //Serial.write(myFile.read());

    }

      //Serial.println(myFile);    

    // close the file:
    myFile.close();

  } else {

    // if the file didn't open, print an error:
    Serial.println("error opening CONFIG.DAT");

  }

  }


//    //Set SMS format to ASCII
//  serialSIM800.write("AT+CMGF=1\r\n");
//  delay(1000);
// 
//  //Send new SMS command and message number
//  serialSIM800.write("AT+CMGS=\"+44"+number+"\"\r\n");
//  delay(1000);
//   
//  //Send SMS content
//  serialSIM800.write("TEST SMS NOISE DETECT");
//  delay(1000);
//   
//  //Send Ctrl+Z / ESC to denote SMS message is complete
//  serialSIM800.write((char)26);
//  delay(1000);
//     
//  Serial.println("SMS Sent!");
Serial.println("this is the phone number: ");
Serial.print(number);

}

}



void insertNo(){

        while(Serial.available()==0) { // Wait for User to Input Data  
  }

telNoString = Serial.readString();


  Serial.print("Initializing SD card...");

  pinMode(10, OUTPUT);

  if (!SD.begin(SD_CS_PIN)) {
    Serial.println("initialization failed!");
    return;
  }

  Serial.println("initialization done.");

  if (SD.exists("CONFIG.DAT")) {

  SD.remove("CONFIG.DAT");
  }

  if (!SD.exists("CONFIG.DAT")) {

  myFile = SD.open("CONFIG.DAT", FILE_WRITE);

  // if the file opened okay, write to it:
  if (myFile) {
    Serial.print("Writing to CONFIG.DAT...");

    myFile.println(telNoString);

    // close the file:
    myFile.close();

    Serial.println("done.");

  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening CONFIG.DAT");
  } 

  // re-open the file for reading:
  myFile = SD.open("CONFIG.DAT");

  if (myFile) {

    Serial.println("CONFIG.DAT:");

    // read from the file until there's nothing else in it:
    while (myFile.available()) {

      Serial.write(myFile.read());

    }

    // close the file:
    myFile.close();

  } else {

    // if the file didn't open, print an error:
    Serial.println("error opening CONFIG.DAT");

  }     

  }
   return;    
}


void loop() {

 while (Serial.available()) {
          delay(10);       
          char c = Serial.read();
          readString  += c;
 }

    if(readString == "setup device") {

      Serial.println(readString);
      readString = "";



insertNo();

    }else{
      if(readString == "start device") {

      Serial.println(readString);
      readString = "";


    }
 sound_detect();   
    }       
}

The section of commented out code are the AT commands to send the sms message.

Answer 1

telNo = (myFile.read()); does that compile? What is the type of telNo ? If it's an int or some other numerical, you won't get that result you want because read() reads characters and not numbers.. The 10 that you see is the ascii code for the newline character ('\\n') which is the first character in the file (that's why you get your number below the CONFIG.DAT: ).

read() reads a byte at a time and returns -1 if none is available. To get the whole content, you should use a loop to read one character at a time and append those characters to a char[] :

unsigned int MAX_SIZE = 100; 
char string[MAX_SIZE];
unsigned int index = 0;
char next_char;
while (next_char = myfile.read()) string[index++] = next_char;
string[index] = '/0'; // terminate with the null character

Now, if you really want an int , you need to filter out the newline , the + and any other non-valid digit and then cast your number to int :

char new_string[MAX_SIZE];
unsigned int i = 0, unsigned int j = 0;
while (i < MAX_SIZE) {  
    if ((string[i] >= 48) && (string[i] <= 57)) 
        new_string[j++] = string[i++];  
    else i++;  
}  
int number = atoi(new_string);

Answer 2

I think I found an answer as follows

// read from the file until there's nothing else in it:
while (myFile.available()) {

            char ltr = myFile.read();
            number += ltr;      

} 

This was found at Text file on SD to String