How to send a text file and append it using Arduino - text

Question

I'm working on a GPS logger project. I have an Arduino Mega set up with a transmitter and receiver and GPS and GSM modules. I also have an Arduino Uno with a transmitter, receiver and buzzer.
When the two devices go too far from each other, the GPS data is pulled and sent to my web server using the GSM module. When I send my file to the server it creates a text file and when I move to another location it overwrites the previous location.
I'm trying to figure out how to append the text file instead of overwriting it. I found a lot of stuff using an SD card shield but nothing without it.
#define GPS_PIN_1 9 // GPS serial pin RX
#define GPS_PIN_2 8 // GPS serial pin TX
#define CHECKPIN 13 // Pin that lights up when things are checked
#define GPSRATE 4800 // GPS baud rate
#include <SoftwareSerial.h>
#include <Flash.h>
#include <Streaming.h>
// How many bytes of input to buffer from the GPS?
#define BUFFERSIZE 100
#define ENDLN
int rx1Pin=31;
int txPin=30;
int tx1Pin=11;
int onModulePin = 2;
int rxPin=12;
SoftwareSerial mySerial = SoftwareSerial(GPS_PIN_1, GPS_PIN_2); //(rx,tx)
SoftwareSerial txSerial = SoftwareSerial(rxPin, txPin);
SoftwareSerial rxSerial = SoftwareSerial(rx1Pin, tx1Pin);
char sendChar ='H';
char incomingChar = 0;
int counter=0;
//GPS variables
int numSats = 0;
int fixType = 0;
int time[] = {
0, 0, 0};
double latitude = 0.0;
double longitude = 0.0;
long altitude = 0;
long maxAlt = 0;
int speed = 0;
int txCount = 0;
int ExOnce = 0;
int FalcomCheck = 0;
int LogCheck =0;
unsigned long GpsOffTime = 0;
unsigned long SmsStart = 0; // SMS-time
char buffer[BUFFERSIZE];
void switchModule(){ // Function to switch the module ON;
digitalWrite(onModulePin,HIGH);
delay(2000);
digitalWrite(onModulePin,LOW);
delay(2000);
}
void setup(){
pinMode(rxPin, INPUT);
pinMode(txPin,OUTPUT);
pinMode(rx1Pin, INPUT);
pinMode(tx1Pin,OUTPUT);
pinMode(GPS_PIN_1, INPUT);
pinMode(GPS_PIN_2, OUTPUT);
pinMode(7, OUTPUT);
pinMode(13, OUTPUT);
digitalWrite(7, HIGH);
pinMode(onModulePin, OUTPUT);
txSerial.begin(4800);
rxSerial.begin(4800);
mySerial.begin(4800);
Serial.begin(19200); // The GPRS baud rate
switchModule(); // Switch the module ON
for (int i=0;i<2;i++){ // Wait 20 sec for connection
delay(10000);
}
}
void loop(){
txSerial.println(sendChar);
Serial.println(sendChar);
for(int i=0; i<6; i++) {
incomingChar = rxSerial.read(); //Read incoming message from TX.
if (incomingChar =='L') {
GPS();//Serial.println("It Works");
}
}
}
void GPS(){
Serial.flush();
// Get a GGA string from the GPS, and
// check if it's a valid fix, and extract the data.
getNMEA("$GPGGA");
delay(100);
numSats = getSats();
fixType = getFixType();
// Make sure we have a valid fix
if (fixType != 0) {
getTime(time);
latitude = getLat();
longitude = getLong();
altitude = getAlt();
// Keep track of the maximum altitude
}
// Convert latitude and longitude into strings.
char latString[12];
char longString[12];
doubleToString(latitude, 4, latString);
doubleToString(longitude, 4, longString);
sprintf(buffer, "%02d:%02d:%02d,%s,%s,%ld",
time[0], time[1], time[2], latString, longString, altitude);
Serial.println(buffer);
if (fixType > 0) {
if (ExOnce==0){
digitalWrite(13, HIGH);
//ExOnce=1;
sendsms();
logftp();
// for (int i=0; i<3; i++) { // Wait 30 sec for a connection.
// delay(10000);
// }
}
}
delay(200);
}
void sendsms(){
Serial.println("AT+CMGF=1"); // Set the SMS mode to text.
delay(500);
Serial.print("AT+CMGS="); // Send the SMS the number.
Serial.print(34,BYTE); // Send the " char.
Serial.print("**********"); // Send the number change *********
// by the actual number.
Serial.println(34,BYTE); // Send the " char.
delay(1500);
Serial.print("Hi this is the General text testing."); // The SMS body
delay(500);
Serial.print(0x1A,BYTE); // End of message command 1A (hex)
delay(20000);
}
void logftp(){
Serial.println("AT&k3"); // Flow activate
delay(1000);
Serial.print("AT+KCNXCFG=0,"); // Connect to GPRS
Serial.print(34,BYTE);
Serial.print("GPRS");
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
//Serial.print("wap.cingular");
Serial.print("epc.tmobile.com");
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
Serial.println(34,BYTE);
delay(1000);
Serial.println("AT+KCNXTIMER=0,60,2,70"); // Set timers
delay(1000);
Serial.println("AT+CGATT=1"); // Network check
delay(1000);
Serial.print("AT+KFTPCFG=0,"); //FTP configuration/connect
Serial.print(34,BYTE);
Serial.print("ftp.insertaddress.com"); //FTP address
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
Serial.print("username"); //Username
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
Serial.print("password"); //Password
Serial.print(34,BYTE);
Serial.println(",21,0"); //Port
delay(500);
Serial.print("AT+KPATTERN=");
Serial.print(34,BYTE);
Serial.print("--EOF--Pattern--");
Serial.println(34,BYTE);
delay(500);
Serial.print("AT+KFTPSND=0,,");
Serial.print(34,BYTE);
Serial.print("log"); //Directory folder of FTP
Serial.print(34,BYTE);
Serial.print(",");
Serial.print(34,BYTE);
Serial.print("pol.txt"); //Text file
Serial.print(34,BYTE);
Serial.println(",0");
delay(12000);
Serial.print(buffer);
Serial.println("--EOF--Pattern--");
delay(12000);
Serial.println("AT+KTCPCLOSE=1,1");
delay(1000);
}
// ------- GPS Parsing ----------
// Reads a line from the GPS NMEA serial output
// Give up after trying to read 1000 bytes (~2 seconds)
int readLine(void) {
char c;
byte bufferIndex = 0;
boolean startLine = 0;
byte retries = 0;
while (retries < 20) {
c = mySerial.read();
if (c == -1) {
delay(2);
continue;
}
if (c == '\n') continue;
if (c == '$') startLine = 1;
if ((bufferIndex == BUFFERSIZE-1) || (c == '\r')) {
if (startLine) {
buffer[bufferIndex] = 0;
return 1;
}
}
if (startLine)
buffer[bufferIndex++] = c;
//}
else {
retries++;
delay(50);
}
}
return 0;
}
// Returns a specific field from the buffer
void getField(int getId, char *field, int maxLen) {
byte bufferIndex = 0;
byte fieldId = 0;
byte i = 0;
while (bufferIndex < sizeof(buffer)) {
if (fieldId == getId) {
// End of string, or string overflow
if (buffer[bufferIndex] == ',' || i > (maxLen - 2)) {
field[i] = 0; // Null terminate
return;
}
// Buffer chars to field
field[i++] = buffer[bufferIndex++];
}
else {
// Advance field on comma
if (buffer[bufferIndex] == ',') {
bufferIndex++; //Advance in buffer
fieldId++; // Increase field position counter
}
else {
bufferIndex++; // Advance in buffer
}
}
}
// Null terminate incase we didn't already..
field[i] = 0;
}
// Polls for an NMEA sentence of type requested
// Validates checksum, silently retries on failed checksums
int getNMEA(char *getType) {
char type[7];
byte retries = 0;
while (retries < 2) {
if (readLine() && validateChecksum()) {
;
getField(0, type, sizeof(type));
if (strcmp(type, getType) == 0) {
return 1;
}
}
else {
retries++;
}
}
Serial.println("Failed to read GPS");
return 0;
}
// Validates the checksum on an NMEA string
// Returns 1 on valid checksum, 0 otherwise
int validateChecksum(void) {
char gotSum[2];
gotSum[0] = buffer[strlen(buffer) - 2];
gotSum[1] = buffer[strlen(buffer) - 1];
// Check that the checksums match up
if ((16 * atoh(gotSum[0])) + atoh(gotSum[1]) == getCheckSum(buffer))
return 1;
else
return 0;
}
// Calculates the checksum for a given string
// returns as integer
int getCheckSum(char *string) {
int i;
int XOR;
int c;
// Calculate checksum ignoring any $'s in the string
for (XOR = 0, i = 0; i < strlen(string); i++) {
c = (unsigned char)string[i];
if (c == '*') break;
if (c != '$') XOR ^= c;
}
return XOR;
}
// Returns the groundspeed in km/h
int getSpeed(void) {
char field[10];
getField(7, field, sizeof(field));
int speed = atoi(field);
return speed;
}
// Return the fix type from a GGA string
int getFixType(void) {
char field[5];
getField(6, field, sizeof(field));
int fixType = atoi(field);
return fixType;
}
// Return the altitude in meters from a GGA string
long getAlt(void) {
char field[10];
getField(9, field, sizeof(field));
long altitude = atol(field);
return altitude;
}
// Returns the number of satellites being tracked from a GGA string
int getSats(void) {
char field[3];
getField(7, field, sizeof(field));
int numSats = atoi(field);
return numSats;
}
// Read the latitude in decimal format from a GGA string
double getLat(void) {
char field[12];
getField(2, field, sizeof(field)); // read the latitude
double latitude = atof(field); // convert to a double (precise)
int deg = (int) latitude / 100; // extract the number of degrees
double min = latitude - (100 * deg); // work out the number of minutes
latitude = deg + (double) min/60.0; // convert to decimal format
getField(3, field, sizeof(field)); // get the hemisphere (N/S)
// sign the decimal latitude correctly
if (strcmp(field, "S") == 0)
latitude *= -1;
return latitude;
}
// Read the longitude in decimal format from a GGA string
double getLong(void) {
char field[12];
getField(4, field, sizeof(field)); // read the longitude
double longitude = atof(field); // convert to a double
int deg = (int) longitude / 100; // extract the number of degrees
double min = longitude - (100 * deg); // work out the number of minutes
longitude = deg + (double) min/60.00; // convert to decimal format
getField(5, field, sizeof(field)); // get the E/W status
// sign decimal latitude correctly
if (strcmp(field, "W") == 0)
longitude *= -1;
return longitude;
}
// Converts UTC time to the correct timezone
void convertTime(int *time) {
// How many hours off GMT are we?
float offset = -5;
long sectime = ((long)(time[0]) * 3600) + (time[1] * 60) + time[2];
sectime += (offset * 3600.0);
// Did we wrap around?
if (sectime < 0) sectime += 86400;
if (sectime > 86400) sectime -= 86400;
// Convert back to time
time[0] = (int)(sectime / 3600);
time[1] = (int)((sectime % 3600) / 60);
time[2] = (int)((sectime % 3600) % 60);
}
// Parses a time field from a GGA string
void parseTime(char *field, int *time) {
char tmp[3];
tmp[2] = 0; // Init tmp and null terminate
tmp[0] = field[0];
tmp[1] = field[1];
time[0] = atoi(tmp); // Hours
tmp[0] = field[2];
tmp[1] = field[3];
time[1] = atoi(tmp); // Minutes
tmp[0] = field[4];
tmp[1] = field[5];
time[2] = atoi(tmp); // Seconds
}
// Gets the hours, minutes and seconds from a GGA string
void getTime(int *time) {
char field[12];
getField(1, field, sizeof(field));
parseTime(field, time);
convertTime(time);
}
// ------ MISC ----------
// Returns a string with a textual representation of a float
void doubleToString(double val, int precision, char *string){
// Print the int part
sprintf(string, "%d", (int)(val));
if(precision > 0) {
// Print the decimal point
strcat(string, ".");
unsigned long frac;
unsigned long mult = 1;
int padding = precision -1;
while (precision--) {
mult *=10;
}
if (val >= 0)
frac = (val - (int)(val)) * mult;
else
frac = ((int)(val)- val ) * mult;
unsigned long frac1 = frac;
while (frac1 /= 10) {
padding--;
}
while (padding--) {
strcat(string, "0");
}
// Convert and print the fraction part
sprintf(string+strlen(string), "%d", (int)(frac));
}
}
// Converts a HEX string to an int
int atoh(char c) {
if (c >= 'A' && c <= 'F')
return c - 55;
else if (c >= 'a' && c <= 'f')
return c - 87;
else
return c - 48;
}

Answer 1

If the server is where the text file is received via SMS/GSM, that server program controls how the file is written or appended. Your posted Arduino code would not need to be changed. On the server, where you now open the file - first check if the file exists and if it does, change the open function to add append mode. Exactly how depends on the OS/language of your server program. But you should be able to figure it out from reading the documentation on the open call.