Daten vom Slave zum Master senden

International Deutsch
2

Nein, wenn der Slave die Initiative ergreifen soll.

Ja, wenn der Master danach fragt. Ein Beispiel hängt vom Slave ab, da gibt es verschiedene "Protokolle".

Programm DS3231 EEPROM schreiben und lesen 
#include <Wire.h>

void i2c_eeprom_writeByte(int deviceaddress, unsigned int eeaddress, byte data)
{
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8)); // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.write(data);
  Wire.endTransmission();
  delay(10);
}

byte i2c_eeprom_read_byte( int deviceaddress, unsigned int eeaddress )
{
  byte rdata = 0xFF;
  Wire.beginTransmission(deviceaddress);
  Wire.write((int)(eeaddress >> 8)); // MSB
  Wire.write((int)(eeaddress & 0xFF)); // LSB
  Wire.endTransmission();
  Wire.requestFrom(deviceaddress, 1);
  if (Wire.available()) rdata = Wire.read();
  return rdata;
};

void MemoryDump(byte I2C_EEPROM_ADDRESS, unsigned int NumberOfBytes)
{
  Serial.print(F("Dump of memory content ("));
  Serial.print(NumberOfBytes);
  Serial.print(F(" bytes) from I2C device at address "));
  Serial.println(I2C_EEPROM_ADDRESS, HEX);
  unsigned int addr = 0;
  byte b = i2c_eeprom_read_byte(I2C_EEPROM_ADDRESS, addr);
  char c;
  while (addr < NumberOfBytes)
  {
    Serial.print(addr, HEX);
    Serial.print("  ");
    c = (char)b;
    Serial.print(c); //print content to serial port
    // if ( (b < 0x20) or (b >= 0x7F) )
    // {
      Serial.print(" (0x");
      Serial.print(b, HEX);
      Serial.print(")");
    // };
    Serial.println();
    addr++; //increase address
    b = i2c_eeprom_read_byte(I2C_EEPROM_ADDRESS, addr);
  };
  Serial.println(F("\nEnd of Dump\n"));
};

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  delay(500);
  Serial.println(F("\nAnfang EEPROM 24c32\n"));
  byte i2cadresse = 0x57;
  Serial.print(i2cadresse);
  Serial.print(" (0x");
  Serial.print(i2cadresse, HEX);
  Serial.println(")");
  MemoryDump(i2cadresse, 10);
  i2c_eeprom_writeByte(i2cadresse, 0x01, 0x45);
  MemoryDump(i2cadresse, 10);
};

void loop() {};