Arduino Help - convert to hex

[blinky]

I'm trying to output the temp from my DS18B20 sensor to the serial output but also convert it to hex and also add # to the end.  So if the sensor outputs 10 degrees as a number I want it to print 0A# to the serial device.

I have been playing around for the past couple of hours and cannot figure it out!  I thought printf might be the way to go but no joy getting that working!  Whats confusing me at the moment is that the first line prints the correct temp but the 2nd line prints nothing.  Can somebody please help?

 

  
     

void loop() {
  sensors.requestTemperatures();
  tempC = sensors.getTempCByIndex(0);
  delay(1000);
  
  Serial.print("C: ");
  Serial.print(tempC);

Serial.println(printf("%2X", tempC ) );

}

 

[rpineau]

char buffer[10];

snprintf(buffer, 10, "C: %02X#", tempC);
Serial.println(buffer);

 

[SilverAstro]

Just guessing :

Serial.println is usually in the form Serial.println(val) or Serial.println(val,format)

where format is DEC or HEX for example.

 

[blinky]

Hi,

 

That prints out 00 to the serial port - 25.00 is the temp in C and the 00 bit is the println(buffer) command

 

25.00 Requesting temperatures...DONE
00

[blinky]

This is the full sketch:

 

#include <DallasTemperature.h>
#include <OneWire.h>
#include <LiquidCrystal.h>

// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
// Data wire is plugged into pin 10 on the Arduino
#define ONE_WIRE_BUS 10

// Setup a oneWire instance to communicate with any OneWire devices
// (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);
/********************************************************************/
// Pass our oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);

float tempC = 0;
float tempF = 0;

void setup(void) {
  Serial.begin(9600);
    lcd.begin(16, 2);
    // declare pin 9 to be an output for buzzer:
    pinMode(9, OUTPUT);
    beep(50);
    beep(50);
    beep(50);
    delay(1000);
    Serial.println("Dallas Temperature IC Control Library Demo");
    // Start up the library
    sensors.begin();
}

 void loop(void)
 {
     // call sensors.requestTemperatures() to issue a global temperature
     // request to all devices on the bus
     /********************************************************************/
     Serial.print(" Requesting temperatures...");
     sensors.requestTemperatures(); // Send the command to get temperature readings
     Serial.println("DONE");
     /********************************************************************/
     //Serial.print("Temperature is: ");
     //Serial.print(sensors.getTempCByIndex(0)); // Why "byIndex"?
     // You can have more than one DS18B20 on the same bus.
     // 0 refers to the first IC on the wire
     delay(1000);
     //beep(10);
     
sensors.requestTemperatures();
tempC = sensors.getTempCByIndex(0);
tempF = sensors.toFahrenheit(tempC);
delay(1000);

//Serial.println(tempC);

char buffer[4];

snprintf(buffer, 4, "%02x", tempC);
Serial.println(buffer);

Serial.print(sensors.getTempCByIndex(0));

lcd.setCursor(0,0);
lcd.print("C: ");
lcd.print(tempC);
lcd.print(" degrees");
lcd.setCursor(0,1);
lcd.print("F: ");
lcd.print(tempF);
lcd.print(" degrees");
 
}

void beep(unsigned char delayms){
  analogWrite(9, 20);      // Almost any value can be used except 0 and 255
                           // experiment to get the best tone
  delay(delayms);          // wait for a delayms ms
  analogWrite(9, 0);       // 0 turns it off
  delay(delayms);          // wait for a delayms ms   
}
 

[blinky]

So if I do this:

int testTemp = tempC;
Serial.println(testTemp, HEX );

It will output 1D for 29 degrees celcius which is what I want :-) THe only problem left is it needs to send # at the end but it auto adds a new line so if I do a Serial.Println("#")  I get it on the next line

[blinky]

Got it!  Serial.print(Temp, HEX);

then Serial.println("#");

[pete_l]

Just output the data with a Serial.print() call and use Serial.println("#"); after that,

[blinky]

Yep see my post, which was the same time as yours, works a treat! Thanks for the help, will no doubt have more questions tomorrow....

[SilverAstro]

8 hours ago, blinky said:

Got it!  Serial.print(Temp, HEX);

then Serial.println("#");

I believe in dropping heavy hints rather than doing all the homework glad you got there