[En-Nut-Discussion] Nut/Net ARM port

[Ralph Mason]

Henrik Maier wrote:
> Hello folks,
>
> There seems to be a considerable interest in Nut/OS for the ARM 
> architecture.
>
> And it is readily available for Ethernut 3, based on the AT91R40008 
> ARM7TDMI CPU. Ethernut 3 is well speced with lot's of RAM and Flash 
> and certainly a good successor of Ethernut 1 and Ethernut 2.
>
> A few people including myself are interested in a small scale ARM7 
> Nut/OS incarnation, featuring the Philips LPC or Atmel AT91SAM CPUs 
> with memory footprints similar to Ethernut 1/2 designs (32 to 64 KByte 
> RAM, 128 KByte to 1 MByte of FlashROM).
I have on my work que in the next few months to do a port to the 
AT91SAM7S -  and also to port out PPP server stuff on there.

>
> Q1: The question to me is, how much RAM and Flash would be needed for 
> an ARM7 based Nut/OS, featuring similar capabilities/power like 
> Ethernut 1/ Ethernut 2 designs.
I think that the 64kb version will work fine for our application.  Ram 
is mostly used in buffers so they don't increase in size because it's a 
32bit processor. Also it can process and free those buffers faster than 
than an AVR.

>
> Q2: And then, what would be a good choice for a NIC? Using the 
> RTL8019AS known from Ethernut 1, the LAN91C111 from Ethernut 2, the 
> DM9000E introduced by Ethernut3, the Microchip ENC28J60 or the 
> integrated MAC from AT91SAMX series.
One of the AT91SAM's has an onboard one - probably a nice choice !
I think they are supposed to be around $7.  I have been quoted $6.50 on 
the AT91SAM7S256 - so it will be lowercost than the AVR soluition.

The only drawbacks with the AT91SAM series that I can see are.

1 No EEPROM  you can use the flash but it's page wise and you need to 
run from ram if you want to write a page, managable for configuration - 
but not so nice.  I am planing on using a dataflash chip with it so it 
can reflash itself, and will also keep settings there

2. Limited ram with no expandability.   I expect this isn't a problem, 
the  faster processor it can process and free incomming data faster

>
> AT91SAMX pros: Integrated NIC, DMA access promises high speed 
> transfers according to Atmel's documentation.
> AT91SAMX cons: No Nut/OS driver yet available
>
> Q3: As there are more people out there, what would be the best 
> approach to share information and collaborate on this topic?
>
Put me on the list.

Ralph