Flash runs at half speed after changed to higher version part

[arunmoondkar]

We are using S25FL064P  flash as a code flash with the microcontroller LPC1850 in qspi mode, SPIFI interface. After that we replaced S25FL064P with S25FL256S as we required higher code size. But when we changed flash to S25FL256S from S25FL064P, we found that code executes with half the speed what it was executed  in S25FL064P. Checked the SPI clock . In S25FL064P it was about 18MHz while in S25FL256S it was about 11 MHz. Also found that out of 4 data lines I02 & I03 data was not presented  in S25FL256S. Has anyone faced this problem ?

[BushraH_91 · Accepted solution]

Hello,

The lower clock frequency (11MHz) for S25FL256S is the reason. Clock is input signal for flash. Flash does not have any control of it. Customer needs to configure the controller at higher clock frequency (e.g., 18MHz as for S25FL064P) to get the similar read speed. S25FL256S can support up to 133MHz SDR Single IO, 104MHZ SDR Dual IO and Quad IO, or 80MHz DDR read.

Regard to IO2 & IO3 data line output, S25FL256S is default working at Single IO or Dual IO mode. So no data output on IO2 & IO3 data lines. To perform Quad IO read, need to set Configuration Register-1 bit1 (QUAD bit) to 1 and use Quad Read commands. However, as the controller reads correct data from flash without data on IO2 & IO3 data lines, the controller is actually reading flash at Single IO mode (output data only on IO1) or Dual IO mode (output data on IO0 & IO1).

Thank you

Regards,

Bushra