Trouble with i2c

Projects Programming
1

I have a Raspberry pi connected to an Arduino over i2c. I am attempting to pass a string to the pi.
My code:

/**
 * ReadSHT1xValues
 *
 * Read temperature and humidity values from an SHT1x-series (SHT10,
 * SHT11, SHT15) sensor.
 *
 * Copyright 2009 Jonathan Oxer <jon@oxer.com.au>
 * www.practicalarduino.com
 */

#include <SHT1x.h>
#include <Wire.h>
#include <UTFT.h>\




// Specify data and clock connections and instantiate SHT1x object
#define dataPin  15
#define clockPin 14
#define SLAVE_ADDRESS 0x04
extern uint8_t BigFont[];
char tStr[7];
char hStr[4];

UTFT    myGLCD(ITDB32S,38,39,40,41);
SHT1x   sht1x(dataPin, clockPin);


void setup()
{
    Serial.begin(38400); // Open serial connection to report values to host
    Serial.println("Starting up");
    myGLCD.InitLCD();
    myGLCD.clrScr();
    myGLCD.setFont(BigFont);
    myGLCD.setBackColor(0, 0, 255);
    Wire.begin(0x04); // join i2c bus
}

void loop()
{
  float temp_c;
  float temp_f;
  float humidity;
  
  // Read values from the sensor
  temp_c = sht1x.readTemperatureC();
  temp_f = sht1x.readTemperatureF();
  humidity = sht1x.readHumidity();


dtostrf(temp_f, 1, 1, tStr);
dtostrf(humidity, 1, 0, hStr);
Serial.print(tStr);
Serial.print(' ');
Serial.print(hStr);
myGLCD.print("Temperature: ",LEFT,0);
myGLCD.print(tStr,15*13,0);
myGLCD.print("Humidity: ",LEFT,15);
myGLCD.print(hStr,12*13,15);
delay(2000);
}

// callback for received data
void receiveData() 
{
    char c = Wire.read();
    Serial.println(c);
}



void writeData (char data)
{
  Wire.beginTransmission(04); // transmit to device #04
                              // device address is specified in datasheet
  Wire.write(data);             // sends value byte  
  Wire.endTransmission();     // stop transmitting

  delay(500);
}

	// callback for received data
void readData ()
{
    int number;
    while(Wire.available())
    {
	 number = Wire.read();
         switch (number)
         {
              case 1:
                  writeData(tStr);
                  break;
              case  2:
                  writeData(hStr);
                  break;
         }
    }
}

The error I am getting is:

readTemp_ino1.ino: In function 'void readData()':
readTemp_ino1:94: error: invalid conversion from 'char*' to 'char'
readTemp_ino1:94: error: initializing argument 1 of 'void writeData(char)'
readTemp_ino1:97: error: invalid conversion from 'char*' to 'char'
readTemp_ino1:97: error: initializing argument 1 of 'void writeData(char)'

What am I doing wrong?

Jim

2

You have defined writeData with a char argument but when you call writeData from the readData function you are passing it a char array (both tStr and hStr are char arrays).
You have to decide whether you really do want writeData to write one character, in which case you need to pass something like tStr[0], or whether writeData should write a string, in which case you need to define it to accept char* and modify the code for writeData so that it writes a string.

Pete

3

Thanks Pete, now I have to chase down logic (me dummy) errors
Jim