Wire.requestFrom() function help needed

Projects General Guidance
1

I am attempting to determine the I2C address of an Nokia LCD screen. I have a sketch that will produce various addresses (i.e. 0x00) as strings. My problem is determining how to use these strings in the Wire.requestFrom() function. From what i can tell the only address this function will accept is one that is predefined (i.e. #define ADRS 0x00). I have attempted to obtain the address from the web but could not find one.

Thanks,
Mark

2

Run this code to scan the I2C bus for devices (thanks, Nick Gammon). If the device is correctly connected to the bus this will give you the address. Set the baud rate in serial monitor to 115200.

#include <Wire.h>

void setup() {
  Serial.begin (115200);

  // Leonardo: wait for serial port to connect
  while (!Serial) 
    {
    }

  Serial.println ();
  Serial.println ("I2C scanner. Scanning ...");
  byte count = 0;
  
  Wire.begin();
  for (byte i = 1; i < 120; i++)
  {
    Wire.beginTransmission (i);
    if (Wire.endTransmission () == 0)
      {
      Serial.print ("Found address: ");
      Serial.print (i, DEC);
      Serial.print (" (0x");
      Serial.print (i, HEX);
      Serial.println (")");
      count++;
      delay (1);  // maybe unneeded?
      } // end of good response
  } // end of for loop
  Serial.println ("Done.");
  Serial.print ("Found ");
  Serial.print (count, DEC);
  Serial.println (" device(s).");
}  // end of setup

void loop() {}
3

Thanks, Yeah i figured out that i didn't have to just enter HEX.

You can actually have 127 address on one bus. I say this because you only increment "i" up to 119.

Thanks,
Mark

4

I think I read somewhere that the lowest 8 addresses are reserved. For what I don't know.