RTEMS with ARM LPC2138

Ian Caddy ianc at goanna.iinet.net.au
Tue Dec 13 14:03:48 UTC 2005

Hi Sam,

 From a quick look at the datsheet, the main thing I would be worried 
about is the amount of RAM (32KBytes) that is available.  The RTEMS 
TCP/IP stack comes from the FreeBSD envinronment and is not friendly to 
small memory footprints if you want to do any serious network 
applications.  I would guess that you need somewhere between 50K-150K of 
RAM to allow enough memory for the IP stack that is used in RTEMS.  This 
  is just really for the mbufs (packet buffers and clusters) required 
since every packet transmitted or received is going to take a single 
1500 byte buffer.  Have a few sockets open at one time and this number 
quickly rises.

Also, the device looks to only have one Ethernet MAC onboard.

We use the Coldfire family with external SDRAM which is cheap and 
provides a large amount of space for networking type applications.

I have also had a look at the Atmel AT91 series, although they seem to 
now only just getting their ARM implementations going.  The single chip 
ones also have RAM memory size issues, but you could go for one of the 
ARM9 cores, which have external memory access, but then I am sure the 
Phillips also have these sorts of processors.

I hope this helps.


Ian Caddy

Sam wrote:
> Hi,
> I want to purchase ARM  LPC2138 and develop some network application 
> based on RTEMS.
> See below for reference of ARM LPC2138 product.
> http://www.embeddedartists.com/products/boards/lpc2138_100eth.php
> Can anyone please tell me whether RTEMS compatible with this device?
> In this webpage, I also found that their Developer Kit is very expensive 
> - 395 EUR.
> Is there other recommendation of embedded hardware device I can use for 
> RTEMS development? I basically need 2 ethernet ports on the device.
> Sam

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