Re: [lwip-users] missing TX packets

[Martin Velek]

Hi,

maybe it is too late but you should also check this site
http://www.lpcware.com/content/nxpfile/lcd-bus-bandwidth-calculator-lpc177x8x
to compute the bandwidth for your LCD controller.

Martin

On Thu, Jan 9, 2014 at 2:50 AM, Lehel Benedek <address@hidden> wrote:
> Hi Marty,
>
> I know that the max recommended setting for the EMC clock is 80MHz.
> Unfortunately I am limited on my board to a 16 bit data-bus to SDRAM,
> however I ran extensive comprehensive memory tests at that higher frequency,
> and everything seems to be OK.
>
>
>
> On Thu, Jan 9, 2014 at 1:00 AM, <address@hidden> wrote:
>>
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>>    1. Re: missing TX packets (Pomeroy, Marty)
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>> ---------- Forwarded message ----------
>> From: "Pomeroy, Marty" <address@hidden>
>> To: "Mailing list for lwIP users" <address@hidden>
>> Cc:
>> Date: Tue, 7 Jan 2014 14:27:37 -0500
>> Subject: Re: [lwip-users] missing TX packets
>>
>> * Don't run EMCCLK above 80MHz!  *
>>
>> On the datasheet for the LPC178x/7x, page 84 and 85 shows that Tcy has a
>> minimum of 12.5ns, which translates to a maximum EMC Clock of 80MHz.  We
>> found out the hard way that it may work on most LPC1788s, but not on some!
>> Not recommended to run it above spec.
>>
>> Our product using LPC1788 has LCD at max refresh rate, AND running the
>> program itself out of DRAM, and no trouble with Ethernet.  Not sure where to
>> look for issues...  make sure everything is using 32 bit transfers and DRAM
>> is configured as a 32 bit interface...
>>
>>
>>
>> ________________________________
>> From: address@hidden
>> [mailto:address@hidden On Behalf Of
>> Lehel Benedek
>> Sent: Sunday, January 05, 2014 7:45 PM
>> To: address@hidden
>> Subject: Re: [lwip-users] missing TX packets
>>
>> I managed to fix the problem by increasing the EMC clock rate from 60Mhz
>> to 104Mhz and lowering the refresh rate of the LCD. The LCD controller was
>> eating up all my bandwith to the external memory. Now both the webserver and
>> the LCD are working nicely.
>> Thanks for your help.
>>
>>
>>
>>
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