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Re: [lwip-users] LPC1768 lpc_low_level_input: Packet dropped witherrors

From: Simon Goldschmidt
Subject: Re: [lwip-users] LPC1768 lpc_low_level_input: Packet dropped witherrors (0xffffffff)
Date: Fri, 28 Nov 2014 10:03:16 +0100

Jan Menzel wrote:
> On 28.11.2014 03:07, Grzegorz Niemirowski wrote:
>> Does your low level driver use DMA? Is AHB-SRAM accessible by DMA?
> Yes, all memory is accessible via DMA. IIRC datasheet says that flash
> can not be used with EMAC.

I don't know the LPC1768, but a quick look at the LPC1769/68/67/66/65/64/63 
Datasheet brings up this:

--- snip ---
On-chip SRAM includes:
-  32/16 kB of SRAM on the CPU with local code/data bus for high-performance 
CPU access.
-  Two/one 16 kB SRAM blocks with separate access paths for higher throughput.
   These SRAM blocks may be used for Ethernet, USB, and DMA memory, as well as
   for general purpose CPU instruction and data storage.
--- snap ---

To me, this implies the first SRAM block is for CPU-only storage (like stack, 
state info, etc) and cannot be used for DMA.


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