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I am having a bit of trouble loading values stored on an SD card and assigning them to variables within my program. I can achieve this as one big block of data, but would much prefer them to be saved to variables whilst in a loop or some other process.

My txt file has the following 6 ints & floats values, which are displayed vertically in the file:

2 0.003200 312 1 0.720000 8

Each of these values I want assigned to variables data1,....2,3,4,5,6. Unfortunately, the code I use below will never achieve this, but I am clueless as to any theory to solve this problem. Thanks in advance.

myFile = SD.open("test.txt", FILE_READ);
    if (myFile) {
    while (myFile.available()) {
        data = myFile.read();
    }
myFile.close();
}
else {
    Serial.println("Read Error");
}
| improve this question | |
  • These are values that change if anyone's thinking why don't I just hard code it instead. – user4163554 May 5 '18 at 20:22
  • Putting all such variables in a struct could be a good choice, as you can then copy the contents of the struct as raw data to/from the card (though getting at it from another system like a PC would require knowledge of how the Arduino compiler packs structs). But you can also read the variables one by one; the big problem at present is that your code doesn't have any variables that it even attempts to load from the card. – Chris Stratton May 6 '18 at 21:22
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File implements Stream just like Serial. so you can use parseInt and parseFloat 

int n = File.parseInt();
float x = File.parseFloat();
Serial.println(n);
Serial.println(x, 6);
| improve this answer | |
  • Thanks for the response. I have just had a search for readByteUntil, it sounds like it could be what I'm looking for, but how would this be implemented into my code. How would I distinguish which goes where? – user4163554 May 5 '18 at 21:10
  • Would I list the parseInts and floats according to the order within my list? And would I put this within the 'available()' method? Thanks. – user4163554 May 5 '18 at 21:11
  • in your case you do not need readBytesUntil. only parse the numbers like in the code snippet in my answer. parseInt and parseFloat skips the spaces. – Juraj May 6 '18 at 5:17
  • myFile = SD.open("test.txt", FILE_READ); if (myFile) { while (myFile.available()) { km = myFile.parseInt(); kmTemp = myFile.parseFloat(); kmrevs = myFile.parseInt(); miles = myFile.parseInt(); milesTemp = myFile.parseFloat(); milesrevs = myFile.parseInt(); Serial.println(km); ........other printlns() } myFile.close(); } else { Serial.println("Read Error"); } – user4163554 May 6 '18 at 9:10
  • Is that what you mean. I could only squeeze in so many characters in this comment. – user4163554 May 6 '18 at 9:10

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