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Which DRAM controller slave ports is able to be accessed through which master ports on a Kinetis K70

Question asked by Claus Stovgaard on Oct 30, 2014
Latest reply on Nov 4, 2014 by Claus Stovgaard

I am doing an application where performance is extremely important, causing the need for pushing the K70 to its performance limits. One of the requirements is that I need to DMA data with approximate 50 MB/s from the Flexbus to DDR memory with very low latency, while the Cortex-M4 also accessing the memory controller.

 

According to the K70 reference manual the DRAM controller’s slave ports can be accessed by the following master ports based on address range.

0x7000_0000-0x7FFF_FFFF

  • Cortex-M4 (M1), eDMA ( M2) can access S5, S6 and S7
  • LCD (M4) can access S5, S6 and S7
  • LCD (M5), eSDHC/NFC (M3), ENET (M7), USB (M6) can access S5

0x8000_0000-0x8FFF_FFFF

  • Cortex-M4 (M1), eDMA ( M2) can access S5
  • LCD (M4) can access S5, S6 and S7
  • LCD (M5), eSDHC/NFC (M3), ENET (M7), USB (M6) can access S5, S6 and S7

 

Though looking in the Freescale training material http://www.freescale.com/files/training_pdf/WBNR_LA2012_K70SP.pdf?lang_cd=en page 27 it states:

0x7000_0000-0x7FFF_FFFF

  • Cortex-M4 (M1), eDMA ( M2) can access S5
  • LCD (M4) can access S6
  • LCD (M5), eSDHC/NFC (M3), ENET (M7), USB (M6) can access S7

0x8000_0000-0x8FFF_FFFF

  • Cortex-M4 (M1), eDMA ( M2) can access S5
  • LCD (M4) can access S6
  • LCD (M5), eSDHC/NFC (M3), ENET (M7), USB (M6) can access S7

 

So what is correct? Is the Cortex M and DMA limited to one slave port together, or is the reference manual correct?

 

If the reference manual is correct. How can I change which slave port a master ports tries with its first attempt. I want to setup the system so the Cortex-M4 always asks S6 first, and the DMA always ask S7, and they both have the highest priority on those ports. The LCD is then able to share the last port together with the USB, ENET etc.

 

I know about the port priority (AXBS_PRSn), and arbitration (AXBS_CRSn) registers, but I can not find any details above the other elements, which I need to know to push the K70 to it full potential.

 

Notice, I have created a service request about this issue (1-3027240671 ) and will try to update this thread if possible with information I receive.

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