External i2c EEPROM library question

A few questions:

1. In this library example what this line means/do?

// Byte to send in all EEPROM
byte data_to_send = 0x23;

2. is the I2C EEPROMs library a good/working library with AT24C32 (which is on DS3231 module)?

3. if i write(over-write) a float value to location address X, do i need to read that location address every time to get that value OR the value on that location address will "load" when turning Arduino ON?

  1. In this library example what this line means/do?

That's the byte value to be written to all cells of that EEPROM. It's your decision if this example makes sense for you.

  1. is the I2C EEPROMs library a good/working library with AT24C32 (which is on DS3231 module)?

It should work with an AT24C32 EEPROM although I never actually tested that. I'm curious where in the DS3231 datasheet you found the reference that it contains an AT24C32 EEPROM.

  1. if i write(over-write) a float value to location address X, do i need to read that location address every time to get that value OR the value on that location address will "load" when turning Arduino ON?

Although I don't know what exactly you mean by that question (are you still writing about the AT24C32 EEPROM?), my interpretation of your question says that the first option (you have to read the cell at least after every power up) is correct.

pylon:
That's the byte value to be written to all cells of that EEPROM. It's your decision if this example makes sense for you.

can you please explain more about this, why should i write that to "all cells of EEPROM"? what does "0=x23" means?

pylon:
It should work with an AT24C32 EEPROM although I never actually tested that. I'm curious where in the DS3231 datasheet you found the reference that it contains an AT24C32 EEPROM.

the chip is soldered on the module and you get two I2C address when scanning I2C.

pylon:
Although I don't know what exactly you mean by that question (are you still writing about the AT24C32 EEPROM?), my interpretation of your question says that the first option (you have to read the cell at least after every power up) is correct.

got it thanks.

can you please explain more about this, why should i write that to "all cells of EEPROM"? what does "0=x23" means?

The author of the library didn't know what you're using it for. So he wrote just an example, that shows you how the library is used. It doesn't have to make sense.

That doesn't read "0=x23" but "data_to_send = 0x23". You should learn a bit about the C/C++ language, 0x45 is the syntax to write the hexadecimal number 45 (which is 69 in decimal) into the code.

the chip is soldered on the module and you get two I2C address when scanning I2C.

It's possible that your module contains both chips but then you should link to that module and not to the datasheet of the other chip on the same module.