teensy-sdfat/SdFat/examples/readCSV/readCSV.ino

// Functions to read a CSV text file one field at a time.
//
#include <limits.h>
#include <SPI.h>

// next line for SD.h
//#include <SD.h>

// next two lines for SdFat
#include <SdFat.h>
SdFat SD;

#define CS_PIN SS

// example can use comma or semicolon
#define CSV_DELIM ','

File file;

/*
 * Read a file one field at a time.
 *
 * file - File to read.
 *
 * str - Character array for the field.
 *
 * size - Size of str array.
 *
 * delim - csv delimiter.
 *
 * return - negative value for failure.
 *          delimiter, '\n' or zero(EOF) for success.           
 */
int csvReadText(File* file, char* str, size_t size, char delim) {
  char ch;
  int rtn;
  size_t n = 0;
  while (true) {
    // check for EOF
    if (!file->available()) {
      rtn = 0;
      break;
    }
    if (file->read(&ch, 1) != 1) {
      // read error
      rtn = -1;
      break;
    }
    // Delete CR.
    if (ch == '\r') {
      continue;
    }
    if (ch == delim || ch == '\n') {
      rtn = ch;
      break;
    }
    if ((n+1) >= size) {
      // string too long
      rtn = -2;
      n--;
      break;
    }
    str[n++] = ch;
  }
  str[n] = '\0';
  return rtn;
}
//------------------------------------------------------------------------------
int csvReadInt32(File* file, int32_t* num, char delim) {
  char buf[20];
  char* ptr;
  int rtn = csvReadText(file, buf, sizeof(buf), delim);
  if (rtn < 0) return rtn;
  *num = strtol(buf, &ptr, 10);
  if (buf == ptr) return -3;
  while(isspace(*ptr)) ptr++;
  return *ptr == 0 ? rtn : -4;
}
//------------------------------------------------------------------------------
int csvReadInt16(File* file, int16_t* num, char delim) {
  int32_t tmp;
  int rtn = csvReadInt32(file, &tmp, delim);
  if (rtn < 0) return rtn;
  if (tmp < INT_MIN || tmp > INT_MAX) return -5;
  *num = tmp;
  return rtn;
}
//------------------------------------------------------------------------------
int csvReadUint32(File* file, uint32_t* num, char delim) {
  char buf[20];
  char* ptr;
  int rtn = csvReadText(file, buf, sizeof(buf), delim);
  if (rtn < 0) return rtn;
  *num = strtoul(buf, &ptr, 10);
  if (buf == ptr) return -3;
  while(isspace(*ptr)) ptr++;
  return *ptr == 0 ? rtn : -4;
}
//------------------------------------------------------------------------------
int csvReadUint16(File* file, uint16_t* num, char delim) {
  uint32_t tmp;
  int rtn = csvReadUint32(file, &tmp, delim);
  if (rtn < 0) return rtn;
  if (tmp > UINT_MAX) return -5;
  *num = tmp;
  return rtn;
}
//------------------------------------------------------------------------------
int csvReadDouble(File* file, double* num, char delim) {
  char buf[20];
  char* ptr;
  int rtn = csvReadText(file, buf, sizeof(buf), delim);
  if (rtn < 0) return rtn;
  *num = strtod(buf, &ptr);
  if (buf == ptr) return -3;
  while(isspace(*ptr)) ptr++;
  return *ptr == 0 ? rtn : -4;
}
//------------------------------------------------------------------------------
int csvReadFloat(File* file, float* num, char delim) {
  double tmp;
  int rtn = csvReadDouble(file, &tmp, delim);
  if (rtn < 0)return rtn;
  // could test for too large.
  *num = tmp;
  return rtn;
}
//------------------------------------------------------------------------------
void setup() {
  Serial.begin(9600);
  
  // Wait for USB Serial 
  while (!Serial) {
    yield();
  }
  Serial.println("Type any character to start");
  while (!Serial.available()) {
    yield();
  }
  // Initialize the SD.
  if (!SD.begin(CS_PIN)) {
    Serial.println("begin failed");
    return;
  }
  // Remove existing file.
   SD.remove("READTEST.TXT"); 
   
  // Create the file.
  file = SD.open("READTEST.TXT", FILE_WRITE);
  if (!file) {
    Serial.println("open failed");
    return;
  }
  // Write test data.
  file.print(F(
#if CSV_DELIM == ','
    "36,23.20,20.70,57.60,79.50,01:08:14,23.06.16\r\n"
    "37,23.21,20.71,57.61,79.51,02:08:14,23.07.16\r\n"
#elif CSV_DELIM == ';'
    "36;23.20;20.70;57.60;79.50;01:08:14;23.06.16\r\n"
    "37;23.21;20.71;57.61;79.51;02:08:14;23.07.16\r\n"
#else
#error "Bad CSV_DELIM"
#endif
));

  // Rewind the file for read.
  file.seek(0);

  // Read the file and print fields.
  int16_t tcalc; 
  float t1, t2, h1, h2;
  // Must be dim 9 to allow for zero byte.
  char timeS[9], dateS[9];
  while (file.available()) {
    if (csvReadInt16(&file, &tcalc, CSV_DELIM) != CSV_DELIM
      || csvReadFloat(&file, &t1, CSV_DELIM) != CSV_DELIM
      || csvReadFloat(&file, &t2, CSV_DELIM) != CSV_DELIM
      || csvReadFloat(&file, &h1, CSV_DELIM) != CSV_DELIM
      || csvReadFloat(&file, &h2, CSV_DELIM) != CSV_DELIM
      || csvReadText(&file, timeS, sizeof(timeS), CSV_DELIM) != CSV_DELIM
      || csvReadText(&file, dateS, sizeof(dateS), CSV_DELIM) != '\n') {
      Serial.println("read error");
      int ch;
      int nr = 0;
      // print part of file after error.
      while ((ch = file.read()) > 0 && nr++ < 100) {
        Serial.write(ch);
      }
      break;            
    }
    Serial.print(tcalc);
    Serial.print(CSV_DELIM);
    Serial.print(t1);
    Serial.print(CSV_DELIM);
    Serial.print(t2);
    Serial.print(CSV_DELIM);
    Serial.print(h1);
    Serial.print(CSV_DELIM);
    Serial.print(h2);
    Serial.print(CSV_DELIM);
    Serial.print(timeS);
    Serial.print(CSV_DELIM);
    Serial.println(dateS);
  }
  file.close();
}
//------------------------------------------------------------------------------
void loop() {
}