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[on:]

  hello..i starting on i2c interface with arduino..

something i 'not understood in red below :

about this code:

#include <Wire.h>

void eeprom_i2c_write(byte address, byte from_addr, byte data) {
  Wire.beginTransmission(address);
  Wire.send(from_addr);
  Wire.send(data);
  Wire.endTransmission();
}

byte eeprom_i2c_read(int address, int from_addr) {
  Wire.beginTransmission(address);
  Wire.send(from_addr);
  Wire.endTransmission();

  Wire.requestFrom(address, 1);
  if(Wire.available())
    return Wire.receive();
  else
    return 0xFF;
}

void setup() {
  Wire.begin();
  Serial.begin(19200);

  for(int i = 0; i < 10; i++) {
    eeprom_i2c_write(B1010100, i, 'f'+i);
    delay(100);
  }

  Serial.println("Writen to memory!");
}

void loop() {
  for(int i = 0; i < 10; i++) {
  byte r = eeprom_i2c_read(B1010100, i);
    Serial.print(i);
    Serial.print(" - ");
    Serial.print(r);
    Serial.print("\n");
    delay(1000);
  }
}

what is the 'f' from " eeprom_i2c_write(B1010100, i, 'f'+i) " ? where it came from ?
cause we use "r" in serial .print (r), not "f" ...
some can explain it ?

many thanks to all 

[Reply #1 on:]

Code:

'f' + i

is simply the ASCII characters 'f' ('f' + 0), 'g', 'h' ... 'o' ('f' + 9)

[Reply #2 on:]

  understood !
but what is the value B1010100 ?
and why after reading from my memory, it send me from Serial.print(r) thoses numbers like 102,103,104,105 instead of the ascii value of f+i ?

 (i gona do again the test to be shure wath i wrote here....i gone see tonight, but if you can tell....)

best..

[Reply #3 on:]

but what is the value B1010100

0x54.

[Reply #4 on:]

  yeah ! what it is ?  code for write or read in memory ?

[Reply #5 on:]

Code:

void eeprom_i2c_write(byte address, byte from_addr, byte data)

Device address, memory address, data.

[Reply #6 on:]

  ok...many thanks to u AWOL....
it's became clearly now..
i gona read again my notes...
 

[Reply #7 on:]

  great ! ok... it's working..this is the real ascii code and the device is well called..
thanks very much...

[Reply #8 on:]

where it came from ?

You should read the device datasheet against the code, then you will know why the code is coded that particular way.