I am doing a simple analog read, the number is of type "long".
I convert it to a string, and pass it to a writetoFile function to write it to an SD card. Any typed string I send in quotes gets written to the SD card but I get this
cannot convert 'String' to 'char*' for argument '1' to 'int writeToFile(char*)'
when I try to pass the converted long variable. Here is the code......I tried everything, its probably something stupid.....Can anyone HELP???
#include <SD.h>
#include <SPI.h>
int CS_PIN = 10;
File file;
void setup()
{
Serial.begin(9600);
initializeSD();
createFile("test.txt");
// writeToFile("This is sample text!");
// closeFile();
// openFile("prefs.txt");
// Serial.println(readLine());
// Serial.println(readLine());
// closeFile();
}
//----------------------------------------------------
void loop()
{
openFile("test.txt");
analogRead(A0);
int FetchVoltage = analogRead(A0);
long Voltage = FetchVoltage * (5.0 / 1023.0);
String Volts;
Volts = String(Voltage, DEC);
writeToFile(Volts, DEC);
closeFile();
Serial.println(Volts);
delay(100);
}
//----------------------------------------------------
void initializeSD()
{
Serial.println("Initializing SD card...");
pinMode(CS_PIN, OUTPUT);
if (SD.begin())
{
Serial.println("SD card is ready to use.");
} else
{
Serial.println("SD card initialization failed");
return;
}
}
int createFile(char filename[])
{
file = SD.open(filename, FILE_WRITE);
if (file)
{
Serial.println("File created successfully.");
return 1;
} else
{
Serial.println("Error while creating file.");
return 0;
}
}
int writeToFile(char text[])
{
if (file)
{
file.println(text);
// Serial.println("Writing to file: ");
Serial.println(text);
return 1;
} else
{
Serial.println("Couldn't write to file");
return 0;
}
}
void closeFile()
{
if (file)
{
file.close();
Serial.println("File closed");
}
}
int openFile(char filename[])
{
file = SD.open(filename);
if (file)
{
Serial.println("File opened with success!");
return 1;
} else
{
Serial.println("Error opening file...");
return 0;
}
}
String readLine()
{
String received = "";
char ch;
while (file.available())
{
ch = file.read();
if (ch == '\n')
{
return String(received);
}
else
{
received += ch;
}
}
return "";
}