Writing to S29GL064S slower than S29GL064N

[MaHa_4528156]

We have recently tested the S29GL064S70TFI070 flash memory device as a drop-in, pin-compatible replacement for the S29GL064N90TFI070 which has now become obsolete.

We are finding that while the programming of the device and any subsequent reads/writes are successful, writing to the device takes significantly longer than on the obsolete device.

(A write of 300 bytes can take approx. 1.5 seconds on the old device, and 2.7 seconds on the new device)

We are surprised by this as the datasheets indicate that the new device has a 70ns access time compared to 90ns for the obsolete device – so we were expecting the writes to be a little faster if anything.

I have read application note “AN220470 – Migration from GL064N to GL064S” and it indicates that the devices should be compatible from a software perspective and I can’t see anything obvious that we need to modify to achieve comparable performance from the two devices.

Do you have an recommendations or advice that might help us achieve the same (or better) performance from the S29GL064S device?

[SudheeshK · Accepted solution]

Hello,

You can use write buffer programming feature of our flash devices to improve the program time. GL064N has 32 byte programming buffer and GL064S has 512 bytes programming buffer. You have to make changes to your software to take advantage of larger programming buffer in GL064S device. Please see the below paragraph from our migration guide (page 2, https://www.cypress.com/file/384776/download​).

"The Write Buffer is designed to reduce the overall system programming time when programming the device. The host system issues a Write to Buffer command, fills the Write Buffer with data, and then issues the programming command. Depending on the device design, a Write Buffer can store up to a maximum Write Buffer size of data.

GL064N has a 32-byte (16 words) Write Buffer while GL064S has a 256-byte (128 words) Write Buffer. The Write Buffer in GL064S is eight times bigger than the one in GL064N. The larger Write Buffer facilitates higher programming throughput and better data alignment with most of the file systems. No software modifications are required to operate with a 32-byte maximum Write Buffer fill supported by GL064N flash in GL064S. Software can be modified to take advantage of the larger GL064S Write Buffer by querying the CFI Programming Buffer Size register at CFI word offset 2Ah and configuring the software to perform larger buffer fills."

Please feel free to ask if you have any other related queries.

Thanks and Regards,

Sudheesh

[MaHa_4528156]

Thank you Sudheesh!

Do you have any source code examples showing how to use the write buffer feature?

[SudheeshK]

Hello,

Sorry for the delay in my response. You can download our low level driver for parallel NOR flash devices from following link: https://www.cypress.com/documentation/software-and-drivers/low-level-driver-nor-flash?source=search&... .

Thanks and Regards,

Sudheesh