Moving RTCS Rx/TX buffers to FlexRAM

stevemiller — Tue, 08 Apr 2014 12:28:28 GMT

Has anyone had success moving RTCS Rx/Tx buffers to external memory?

On my board design I have some external SRAM available which I have configured the FlexMemory for and its works well (according to my memory tests). I've moved several of my application memory pools to the SRAM and they function as expected.

I have had some partial success moving some of the RTCS partitions out to the external SRAM by defining a memory pool using global _RTCS_mem_pool. That has worked fine.

But when I try to move the actual Rx/Tx buffers to the FlexMemory ( by defining _BSP_sram_pool and the user_config.h defines, see code snippet from macnet_init.c) I dont get any response for TCP stack.

#if BSPCFG_HAS_SRAM_POOL && BSPCFG_ENET_SRAM_BUF

buf_ptr = _mem_alloc_system_from(_BSP_sram_pool, rxsize + txsize + ssize + lsize);

#else

buf_ptr = _mem_alloc_system_uncached(rxsize + txsize + ssize + lsize); // temporary fix for cache problems... previously _mem_alloc_system

endif

Its likely that its some caching related issue, but I find it hard to find documentation on how to disable cacheing on FlexMemory (or sections of it).

I tried the user_config MQX_USE_UNCACHED_RAM but its conflicts with my lw_mem_allocs that I use and I'm loathe to give up because of shared app code that I use with another board running a Kinetis K21.

I'm using MQX 4.0.2 on a Kinetis K60

Re: Moving RTCS Rx/TX buffers to FlexRAM

Luis_Garabo — Thu, 10 Apr 2014 19:18:10 GMT

Hi Steve,

This is definitely not recommended. We have already experimented that when the Tx/Rx buffers are moved out of the internal SRAM causes failures in the TCPIP even it they were successfully configured. This also applies for the USB buffers.

Regards,
Garabo

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Moving RTCS Rx/TX buffers to FlexRAM

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