Page write mode on M24C64-A125

[RachidBen]

Dear ST Community, 

Currently using the M24C64-A125 as EEPROM. We have a performance challenge in which we need to write a certain amount of data in less than 100ms. We checked the datasheet and we found out that The Page Write mode allows up to 32 bytes to be written in a single Write cycle. Which reduce the amount of time to 4ms maximum for 32 bytes.

However, we are confused about the relationship with /WC pin. When we want to use the Page Write Mode, shall we pull up the WC pin untill the stop command is sent and then pull that down ? or it shall be pull down at the beginning of the transfer of data ? 

Regards

Rachid

[Peter BENSCH]

Welcome @RachidBen, to the community!

The signal /WC was shown in the diagram in a somewhat ambiguous way. You will find a description of its function in the data sheet, section 2.4:

Write Control (WC)
This input signal is useful for protecting the entire contents of the memory from inadvertent write operations. Write operations are disabled to the entire memory array when Write Control (WC) is driven high. Write operations are enabled when Write Control (WC) is either driven low or left floating.
When Write Control (WC) is driven high, device select and address bytes are acknowledged, Data bytes are not acknowledged.

and above your picture in section 4.1.2:

Page Write
[...]
The bus master sends from 1 to N(1) bytes of data, each of which is acknowledged by the device if Write Control (WC) is low (note: this means active).
If Write Control (WC) is high, the contents of the addressed memory location are not modified, and each data byte received by the device is not acknowledged, as shown in Figure 6. [...]

Does this answer your question?

Regards
/Peter

[RachidBen]

Dear @Peter BENSCH, 

Thank you for the clarification. Indeed, we already saw the /WC pin functionnality on the mentionned chapter. and that is a write protection pin to inhibit writing. However, the question is still open on how to enable the page write mode, is there any special procedure ? or that is automatically done be EEPROM ? Because the only difference we see between the two modes is /WC pin difference. We want to achieve the 4ms for 32 Bytes as we are having some performance issues on our system.

Regards

Rachid

[Peter BENSCH · Accepted solution]

The page write mode is automatically activated by the EEPROM if more than one byte is written until the stop condition. This can also be seen in the component drivers of the software examples for the M24xx EEPROMs.

Good luck!
/Peter

[RachidBen]

Thank you very much @Peter BENSCH