[SOLVED] Can't read EEPROM addresses values

Using Arduino Programming Questions
1

Hi,

I have this EEPROM, and here is my code :

#include <Wire.h>
char c;
void setup()
{
  Wire.begin();
  Serial.begin(115200);
}
void loop()
{

  Wire.beginTransmission(0x50);
  Wire.write(0x00);
  Wire.write(0x45);
  Wire.endTransmission();

  Wire.beginTransmission(0x50);
  Wire.write(0x00);
  Wire.endTransmission(false);
  
  Wire.requestFrom(0x50,1);
  if(1<=Wire.available()){
    c = Wire.read();
    Serial.print(c, HEX); quelle patte est activée ou pas
    Serial.print(", ");
  }else
    Serial.println("No data");
  Serial.println();
  delay(200);
}

And I always get the "No data".

I know the EEPROM is working because when I scan the I2C with a simple I2CScanner I can see it at address 0x50.

What am I doing wrong ? Because this code :

#include <Wire.h>
void setup()
{
  Wire.begin();
  Serial.begin(115200);
}
void loop()
{
  Wire.requestFrom(0x50, 2);
  while(Wire.available())  
  {  
    char c = Wire.read();  
    Serial.print(c & 0xFF, BIN);
    Serial.print(", ");  
  }  
  Serial.println();
  delay(200);
}

Give some values... Also I can see the 45 I have written with the other code..

Thank you for your help.

2

This example:
https://forum.sparkfun.com/viewtopic.php?t=25140
Does NOT use "Wire.endTransmission(false);" when setting the read address. Try "Wire.endTransmission();" instead.

3

Thank you for your help !

In the example there is a delay :

delay(10);                    // Without a short delay, the EEPROM is still
                                // writing when you start to write the next block
                                // Feel free to experiment with the delay length

Adding a delay just after the first "Wire.endTransmission()" and removing the false from the second one did the job.

EDIT : Found this link : https://www.hobbytronics.co.uk/arduino-external-eeprom

4

smem.png

The EEPROM location takes about 5 ms time (known as write cycle time) to get 1-byte data written into it. Your program codes do not contain the required write cycle delay it; so, no data has been actually written into location 0x00. Please, execute the following codes which are taken from your original post and slightly modified.

#include <Wire.h>
byte c;
void setup()
{
  Wire.begin();
  Serial.begin(115200);

  Wire.beginTransmission(0x50);
  Wire.write(0x00);   //EEPROM location
  Wire.write(0x45);   //data for EEPROM location
  Wire.endTransmission();
  delay(5);                            //write cycle delay
  
  Wire.beginTransmission(0x50);
  Wire.write(0x00);   // point EEPROM location
  Wire.endTransmission();


  Wire.requestFrom(0x50,1);
  //if(1<=Wire.available()){
   c = Wire.read();
   Serial.print(c, HEX); // Serial Monitor should show 45 //quelle patte est activée ou pas

}

void loop()
{

}

smem.png