Not able to write Write 16 bytes only in QSPI.

[PYada.1]

I am Using STM32l562E-DK, I am using SBSFU (ported from NUCLEO-L552ZE-Q).

I want to store 16-byte data at 0x61000 location in external Flash.

If I perform the following steps, My data is modified as expected.

1) Read 4 KB sector data

2) Modify required parameter 

3) Erase 4KB sector

4) Write modified 4KB data 

But If I don't perform 3rd step, my modified data is not related. What is a possible reason for it?

I am using low_level_ospi_flash.c to perform read, erase, and write data. I have set the correct range in write and erase in low_level_ospi_device.c file

Is it possible to exclude 3rd step ? What is a method to writing data without erasing the whole sector?

[PYada.1]

@Frantz LEFRERE​ , Can you please help me regarding this?

[Frantz LEFRERE]

It is in the nature of flash memory that write operations only allow transition of a bit from 1 to 0. To set a bit from 0 to 1 requires an erase operation and an erase operations applies to an entire erase block. The size of an erase block varies between devices.