Arduino uint8_t variables

Question

I'm having trouble with some arduino code. im using an Ethernet tutorial code i found and some IR emitter and receiver code i found, and im trying to combine them.

http://www.ladyada.net/learn/sensors/ir.html

http://g33k.blogspot.com/2010/09/arduino-data-webserver-sample-web.html

Both codes work fine by themselves.

The code compiles but when i call the following void IRDetector() , it doesn't work. I have debugged it and so far ive found when i use the variable uint8_t or uint16_t (ive tried replacing them with ints and longs). Do i have to import and libraries to use uint8_t ? Any thoughts?

Any help would be appreciated.

 uint16_t pulses[100][2];  // pair is high and low pulse 
   uint8_t currentpulse = 0; // index for pulses we're storing

    uint8_t highpulse, lowpulse;  // temporary storage timing

      void IRDetectCode(void)
   {
    while(true){

highpulse = lowpulse = 0; // start out with no pulse length

while (IRpin_PIN & (1 << IRpin)) {
  // pin is still HIGH

  // count off another few microseconds
  highpulse++;
  delayMicroseconds(RESOLUTION);

  // If the pulse is too long, we 'timed out' - either nothing
  // was received or the code is finished, so print what
  // we've grabbed so far, and then reset
  if ((highpulse >= MAXPULSE) && (currentpulse != 0)) {
     Serial.print(" usec, ");
  //  printpulses();
    //currentpulse=0;
    return;
  }
}
// we didn't time out so lets stash the reading
pulses[currentpulse][0] = highpulse;

// same as above
while (! (IRpin_PIN & _BV(IRpin))) {
  // pin is still LOW
   Serial.print(" usec, ");
  lowpulse++;
  delayMicroseconds(RESOLUTION);
  if ((lowpulse >= MAXPULSE)  && (currentpulse != 0)) {
  //  printpulses();
  //  currentpulse=0;
    return;
  }
}
//pulses[currentpulse][1] = lowpulse;

          // we read one high-low pulse successfully, continue!
       currentpulse++;
  }
    }

  void printpulses(void) {
        Serial.println("\n\r\n\rReceived: \n\rOFF \tON");
         for (uint8_t i = 0; i < currentpulse; i++) {
            Serial.print(pulses[i][0] * RESOLUTION, DEC);
            Serial.print(" usec, ");
            Serial.print(pulses[i][1] * RESOLUTION, DEC);
            Serial.println(" usec");
           }

         // print it in a 'array' format
     Serial.println("int IRsignal[] = {");
     Serial.println("// ON, OFF (in 10's of microseconds)");
         for (uint8_t i = 0; i < currentpulse-1; i++) {
             Serial.print("\t"); // tab
             Serial.print(pulses[i][1] * RESOLUTION / 10, DEC);
             Serial.print(", ");
            Serial.print(pulses[i+1][0] * RESOLUTION / 10, DEC);
           Serial.println(",");
        }
          Serial.print("\t"); // tab
     Serial.print(pulses[currentpulse-1][1] * RESOLUTION / 10, DEC);
      Serial.print(", 0};");
        }

uint8_t (and similar types) are defined in stdint.h. There's nothing special, it's just a typedef to something like unsigned char. — TJD
– TJD, Commented May 4, 2012 at 23:28

Chris Grimmett · Accepted Answer · 2013-03-23 21:30:47Z

5

The uint8_t is a unsigned integer on 8 bits. In Arduino, it's called a "byte", so you can use it like that:

for (byte i = 0; i < currentpulse; i++) {....

It's far better than using the Arduino's "int" type (== int16_t) or "unsigned int" (== uint16_t) because the ATmega328 is 8-bit. So handling an 8-bit var is faster (a lot).

I hope it can help.

edited Mar 23, 2013 at 21:30

Chris Grimmett

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answered May 30, 2012 at 12:06

user1176298

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