Über den I2C Bus kann man sehr elegant Module anbauen. Um dies zu veranschaulichen, sind in diesem Beispiel drei I2C Module angeschlossen:

• Adafruit 8×8 Mini Matrix (Adresse 0x72)
• Adafruit 14-Segemnt AlphaNum Anzeigt (Adresse 0x70)
• 128×64 OLED mit SSD1306 (Adresse 0x3c)

Beim I2C ist die Adresse des Moduls am wichtigsten. Um zu sehen, ob man das Modul richtig angweschlossen hat, kann man den Code i2cscanner verwenden (identisch zum Arduino code bis auf den Aufruf der wire Unterroutine twi_writeTo)

i2cScan.ino

// --------------------------------------
// i2c_scanner
//
// Version 1
//    The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
//     Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 26  2013
//    V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
//    by Arduino.cc user Krodal.
//    Changes by louarnold removed.
//    Scanning addresses changed from 0...127 to 1...119,
//    according to the i2c scanner by Nick Gammon
//    http://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
//    As version 4, but address scans now to 127.
//    A sensor seems to use address 120.
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//
#include <Wire.h>
 
void setup()
{
  Wire.begin();
  Serial.begin(9600);
  Serial.println("\nI2C Scanner");
}
 
void loop()
{
  byte error, address;
  int nDevices;
  Serial.println("Scanning...");
  nDevices = 0;
  for(address = 8; address < 127; address++ ) 
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.print(address,HEX);
      Serial.println("  !");
      nDevices++;
    }
    else if (error==4) 
    {
      Serial.print("Unknow error at address 0x");
      if (address<16) 
        Serial.print("0");
      Serial.println(address,HEX);
    }    
  }
  if (nDevices == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");
  delay(5000);           // wait 5 seconds for next scan
}

Im Serial Monitor zeigen sich die Module an den erhofften Adressen:

I2C Scanner
Scanning...
I2C device found at address 0x3c
I2C device found at address 0x70 
I2C device found at address 0x72
done

Zur Ansteuerung der Module können die Adafruit Bibliotheken fast unverändert verwendet werden. Lediglich beim Code für das 14-Segment Modul musste der Aufruf von pgm_read_word entfernt werden, da PIC32 kein PROGMEM kennt.

⇒HelvePic32