Kinetis K65 with SDRAM 512Mb

[jdohnal]

Is it possible to connect the MCU MK65 to SDRAM MT48LC64M8A2? SDRAM has 8192 rows by 2048 columns, 10 columns A[9:0] SDRAM can be connected to A[16:9], A[22:20], A18 of MK65FN2M0VMI18, which is described in table 35-9 K65P169M180SF5RMV2.pdf. But on the page 890 is "The maximum SDRAM address size is 128 Mbits" and I want to connect SDRAM 512Mbit (64MB). Isn't this limit determined only for FlexBus and SDRAM can exceed this limit?

[Kan_Li · Accepted solution]

Hi Jiri Dohnal,

I checked the data sheet of MT48LC64M8A2, and looks like you are going to use the following configuration in red circle with table 35-9 , right?

If yes, I think maybe you have ignored the BA0 and BA1, which should be also listed as two of the address lines, such as table 35-14

so if you connected in the way of table 35-9 shown, only 128Mbit can be accessed with predefined states on BA0 and BA1, it is not a limitation for flexbus, but for SDRAM mapping.

Hope that makes sense,

Please kindly let me know if you have any issue.

Have a great day,
Kan

NXP Technical Support
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[jdohnal]

Hi Kan_Li,

you're right, I forgot that bank adresses BA0, BA1 should have been connected to GPIOs and switch banks manually.

Can I ask you how to connect more then one SDRAM to K65/K66? On an older versions of Kinetis (K60, K61), this limitation was only 1Gb. Now on newer and faster Kinetis I can connect 2 SDRAM (diferentiated by SDRAM_CS0, SDRAM_CS1), every with 128Mbit limitation?

Thank you very much for your answer.

Jiri Dohnal