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Re: memory requirements, TI OMAP 5910 (ARM 925T)?


Thanks very much for your thoughts below on memory usage, Gary!

When you estimated "300-400KB of code, which might possibly run from
FLASH," did you mean code and data, or just code? (You also mentioned
256KB for the networking stack's data, so I'm wondering if that's included 
in your ballpark figure of 300-400KB.)

What I'm wondering now, and will try to investigate on my own (but 
comments are welcome!), is whether I can disable networking most of
the time, running a small eCos core of non-networking code and data from 
internal memory. Then when I need to connect to the network, maybe power 
up the ethernet chip and an external RAM chip, loading the code and 
initialized data for networking support into the external RAM chip with a 
second-stage bootloader or something. (Uninitialized data for network
support would be out on the external chip too.) So I need to do more 
reading on both eCos and the OMAP 5910. But any thoughts on that approach?

Thanks!

Jim


On 18 Jul 2003, Gary D. Thomas wrote:

> On Fri, 2003-07-18 at 15:43, Jim Partan wrote:
> > Hi,
> > 
> > I'm starting to evaluate the TI OMAP 5910 (ARM 925T) for a new embedded 
> > system. I'd like to use eCos. Right now I'm specifically trying to 
> > estimate the approximate memory requirements. I'm just getting the eCos
> > configuration tool up and going, but if anyone has a vaguely similar
> > system and can let me know what their approximate memory usage is, that 
> > would be great!!
> > 
> > I'm interested in using (on ARM 925T):
> > 
> > 	TCP/IP stack with embedded webserver
> > 	ethernet driver (perhaps SMSC LAN91c111)
> > 	flash filesystem
> > 	RS232 serial port ('5910 has some integrated UARTs)
> > 	an external realtime clock (probably on I2C bus)
> > 	maybe a few other very small things (watchdog, etc)
> > 
> > 	ideally USB as well, but this is not at all critical
> > 		(the '5910 has an integrated USB interface)
> > 
> > The OMAP 5910 has 192kbytes of internal SRAM. I'd love to avoid
> > putting an external RAM chip on the board. The catch is that
> > the internal SRAM is shared with a TI DSP sharing the same
> > package (it's a dual-core package, ARM 925T and TI '55x DSP),
> > and of course I'd like as much RAM as possible dedicated to the
> > DSP side of things...
> > 
> 
> Not counting any particular other application support (like
> the web content generation, etc), a rough guess is that you're
> talking 300-400KB of code, which might possibly run from FLASH.  
> Having only 192KB RAM might be doable, but I think you'd suffer 
> network performance.  By default, the network stack uses 256KB 
> for it's own data (buffers, structures, etc), but of course 
> this is configurable.  In this case, you'd be trading memory for
> performance.  It does look like external RAM would be useful
> (probably even required) for you to make much of a useful system.
> 
> 


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