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Topic: sscanf(); help (Read 773 times) previous topic - next topic


so i have a problem using the sscanf();. I have a GPS and it sends various data over serial communications to my touchscreen. Right now i just want to get the hours and minutes but when i used the sscanf it only grabbed the hours but not the minutes and im new to this function so i dont know what the problem is. heres my code:

Code: [Select]
#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>
#define RXpin 3            //touchshield slide pins
#define TXpin 2
// If you're using a GPS module:
// Connect the GPS Power pin to 5V
// Connect the GPS Ground pin to ground
// If using software serial (sketch example default):
//   Connect the GPS TX (transmit) pin to Digital 3
//   Connect the GPS RX (receive) pin to Digital 2
// If using hardware serial (e.g. Arduino Mega):
//   Connect the GPS TX (transmit) pin to Arduino RX1, RX2 or RX3
//   Connect the GPS RX (receive) pin to matching TX1, TX2 or TX3

// If you're using the Adafruit GPS shield, change
// SoftwareSerial mySerial(3, 2); -> SoftwareSerial mySerial(8, 7);
// and make sure the switch is set to SoftSerial

// If using software serial, keep these lines enabled
// (you can change the pin numbers to match your wiring):
SoftwareSerial mySerial(6, 7);
SoftwareSerial touchSerial = SoftwareSerial(RXpin, TXpin);
Adafruit_GPS GPS(&mySerial);
// If using hardware serial (e.g. Arduino Mega), comment
// out the above six lines and enable this line instead:
//Adafruit_GPS GPS(&Serial1);

// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences.
#define GPSECHO  true

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;
void useInterrupt(boolean); // Func prototype keeps Arduino 0023 happy
int tzhour;
int tzminute;
int tzseconds;
int tzmonth;
int tzyear;
int tzday;
void setup() 
  // connect at 115200 so we can read the GPS fast enough and echo without dropping chars
  // also spit it out
  //Serial.println("Adafruit GPS library basic test!");

  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  // uncomment this line to turn on only the "minimum recommended" data
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time
  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  // Request updates on antenna status, comment out to keep quiet

  // the nice thing about this code is you can have a timer0 interrupt go off
  // every 1 millisecond, and read data from the GPS for you. that makes the
  // loop code a heck of a lot easier!

  // Ask for firmware version

// Interrupt is called once a millisecond, looks for any new GPS data, and stores it
  char c = GPS.read();
  // if you want to debug, this is a good time to do it!
#ifdef UDR0
  if (GPSECHO)
    if (c) UDR0 = c; 
    // writing direct to UDR0 is much much faster than Serial.print
    // but only one character can be written at a time.

void useInterrupt(boolean v) {
  if (v) {
    // Timer0 is already used for millis() - we'll just interrupt somewhere
    // in the middle and call the "Compare A" function above
    OCR0A = 0xAF;
    TIMSK0 |= _BV(OCIE0A);
    usingInterrupt = true;
  } else {
    // do not call the interrupt function COMPA anymore
    TIMSK0 &= ~_BV(OCIE0A);
    usingInterrupt = false;

uint32_t timer = millis();
const int offset = 4;  // Central Daylight Time (USA)
void loop(){                    // run over and over again
  // in case you are not using the interrupt above, you'll
  // need to 'hand query' the GPS, not suggested :(
  if (! usingInterrupt) {
    // read data from the GPS in the 'main loop'
    char c = GPS.read();
    // if you want to debug, this is a good time to do it!
    if (GPSECHO)
      if (c) Serial.print(c);
  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences!
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another
  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // approximately every 2 seconds or so, print out the current stats
  if (millis() - timer > 1000) {
    timer = millis(); // reset the timer
    Serial.print("\nTime: ");
     if (GPS.hour >= 0 && GPS.hour < offset) {
        tzhour = GPS.hour + 20;
      else {
        tzhour = GPS.hour - offset;

        tzhour = tzhour - 12;

      tzminute = GPS.minute;

touch screen code:
Code: [Select]
int tzhour;
int tzminute;
char out[32];
void setup(){
void loop(){
char charIn = 0;
byte i = 0;
char stringIn[32] = "";
charIn = Serial.read();
stringIn[i] = charIn;
stringIn[i] = '\0';
int tzhour;
int tzminute;

  // Clear screen and display the serial buffer as text
  sscanf(stringIn, "%d,%*s,%d", &tzhour, &tzminute);


The definition of the s format specifier is that it consumes: 
"Any number of non-whitespace characters, stopping at the first whitespace character found."

Minutes do not look like whitespace characters.  Perhaps you intended:

sscanf(stringIn, "%d,%*1s,%d", &tzhour, &tzminute);

(notice the added 1)

It would help if you would tell us what text string the GPS unit produces.

Good luck!

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