topic K20 with external SRAM in Kinetis Microcontrollers

K20 with external SRAM

michaelschmid — Wed, 13 Mar 2013 13:15:50 GMT

I am designing a new device, and plan to use the MK20DX64VLH7 Kinetis MUC. This system need 256kB external SRAM.

I have read the thread K20 external memory interface description wanted. But still not absolute sure. From the datasheet of the MK20DX64VLH7, there are FB_AD[17:0], FB_RW, FB_ALE/CS1/TS, FB_CS0#.

The SRAM Chip have A[17:0], D[15:0], WE#, OE#, CS1# and CS2.

Can i use that SRAM in multiplexed mode, by

latching the FB_AD[17:0] to SRAM_A[17:0],

FB_AD[15:0] to SRAM_D[15:0],

FB_RW to SRAM_WE#,

FB_ALE to the latched_FB_AD[17:0]

FB_CS0 to SRAM_CS0#?

Or do i any more glue logic? In the link above, the FB_AD[31:16] are used for data bus, but those pins are not available on the 64pin MK20DX64VLH7.

For this K20 device, the Fsys frequency is 36MHz. What could i expect as burst read/write rate? Considered the SRAM fast enough, are additional wait states required?

Any help or shared experiences with a multiplexed SRAM on the Kinetis would be helpful.

Re: K20 with external SRAM

adriansc — Wed, 13 Mar 2013 17:53:56 GMT

Hi,

According to K20 product brief (page 25):

http://www.freescale.com/files/32bit/doc/prod_brief/K20PB.pdf

You can refer to AN4393 "Using FlexBus Interface for Kinetis Microcontrollers" Applicaction Note

http://cache.freescale.com/files/microcontrollers/doc/app_note/AN4393.pdf

It looks that latching in multiplexed mode as you wrote can work.

Hope this helps.

Re: K20 with external SRAM

Monica — Tue, 19 Mar 2013 20:17:11 GMT

Michael,

how is it going? Was it helpful?

We'd like to know! :smileywink:

Regards!

Re: K20 with external SRAM

michaelschmid — Wed, 20 Mar 2013 09:05:35 GMT

Dear Monica,

thanks. First of all, i was impressed about the fast answer. And happy, that the answer was positive for my problem.

Actually, I have not implemented the details, so i dont know if the resulting hardware will work as expected. But i am positive for that.

best regards,

Re: K20 with external SRAM

Monica — Wed, 20 Mar 2013 19:40:20 GMT

Excellent Michael, we'll be around! :smileywink:

Re: K20 with external SRAM

bjoernjohanness — Thu, 07 Nov 2013 18:08:53 GMT

Hi, I am wondering the same thing.

The application note surely helps but does not show explicitly how to connect a 16bit(data bus) SRAM. I would REALLY appreciate to know exactly how to connect SRAM for maximum performance, preferably with a specific suggested SRAM device.

Thanks a ton!!

//bjoern

Re: K20 with external SRAM

Monica — Thu, 07 Nov 2013 22:04:42 GMT

Hello Bjoern,

I would recommend you submit a Service Request :smileyhappy:

Best,

Monica