I'd like to log my data on my Arduino one file at a time. I'd like the filename to be a combination of the number of milliseconds that have passed + some ID. For example, GPS data would be millis()+"GPS".
I tried the following code, but it doesn't like the fact that I am using a String
. I could use a char array, but the length would always be dynamic. Is there a way to do this with at string somehow?
static void writeToSD()
{
String logEntry = " GPS: ";
logEntry += GPSString;
String filename = String(millis());
filename += "GPS";
Serial.println(logEntry);
Serial.println(filename);
File dataFile = SD.open(filename, FILE_WRITE);
// If the file is available, write to it:
if (dataFile) {
dataFile.println(logEntry);
dataFile.close();
Serial.println("Closed");
}
// If the file isn't open, pop up an error:
else {
Serial.println("error opening file");
}
}
You could try the following
char fileNameCharArray[filename.length()];
filename.toCharArray(fileNameCharArray, filename.length())
File dataFile = SD.open(fileNameCharArray, FILE_WRITE);
sprintf (filename, "%ld-GPS", millis());
请注意,不推荐在Arduino上使用String, 因为有充分记录的内存泄漏/碎片问题 。
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