I am using an M24C64 EEPROM with an STM32F4, but I have a problem with sequential writing. When I try to write 16-bit data sequentially like this, I get HAL_I2C_ERROR_AF error:


But if I put a 5 ms delay between write operations, I could write successfully.

How can I write faster to the EEPROM?


2 Answers 2


Some sort of delay is required because the device is busy writing the data.

The datasheet for this device gives you two options to minimize it:

  • page writes (section 5.1.2) to write 32 bytes at a time
  • polling instead of using a fixed, worst-case delay of 5ms (section 5.1.6)

If you do page writes, be careful that your addresses are aligned with page boundaries, otherwise the device will silently corrupt the data.

  • \$\begingroup\$ Thank you for your explanations, if I use the page write, When I read do I have to page read? \$\endgroup\$
    – gogogo
    Jul 2, 2021 at 5:58
  • 3
    \$\begingroup\$ You can use any method to read the data, it doesn't remember how it was written. The different methods are all explained in the datasheet. \$\endgroup\$
    – DamienD
    Jul 2, 2021 at 8:16

You can't write single bytes any faster. Each write operation to a page takes up to 5ms to complete.

However, what you can do is to write multiple bytes into a page, as the chip has a page size of 32 bytes.

So each write of up to 32 bytes within a page takes up to 5ms.


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