I2C address issue

Projects Programming
1

hi,

i am working on a RTC module DS1307 with arduino uno using i2c comm protocol

the slave address mentioned in data sheet is 0x68 which is fine i can communicate with the RTC and i can read one of the register value also

#include<Wire.h>

#define ADDRS 0x68   // RTC DS1307 address
int val =0;
void setup() {

  Serial.begin(9600);
  Wire.begin();


}


void loop() {

  Wire.beginTransmission(ADDRS);  // slave address in
  Wire.write(0x05);               // 0x05 gives the month 
  Wire.endTransmission();// == 0

  Wire.requestFrom(0x68, 1);
  while(Wire.available())
  {
    val = Wire.read();  // command register
    Serial.print("val:"); Serial.println(val);
  }
    
}

but when i use the slave address different lets say 0x60 instead of actual adress 0x68
i am getting a random values
why is it happening ?

i thought slave wont respond untill and unless if we give proper address

2

why is it happening ?

A more important question is why you are asking a non-existent address to supply data.

3

PaulS:
A more important question is why you are asking a non-existent address to supply data.

PaulS:
A more important question is why you are asking a non-existent address to supply data.

ha ! i wanted to check what happens when i give a wrong slave address , will the slave respond for
wrong address ? if slave respond for wrong address what happens next ?

as i knew i2c comm starts with pulling down the SDA line low then send the address +r/w (8 bits) then

  1. when the slave address is right then ack bit will generate then fallows data read or write operation

  2. when the slave address is wrong then non-ack bit will generate then what happens ?

correct me if i am wrong ?