Lpc2000

> ok, I am sure microchip is doing good job here, but I have some 
doubts 
> and major one is:
> Operating Current 250 mA ??? why do they need quarter Amp?
>


Hi all

I have been watching the ENC28J60 for over a year now. Originally 
samples were promised for Feb. 2005 but never arrived. In the mentime 
have done a number of embedded Internet projects using the MC9S12NE64 
(HCS12 with embedded 10/100 LAN MAC + PHY) - a good solution for space 
sensitive devices when the relatively low resources can be tolerated - 
however using a good compiler you can still pack a lot of 
functionality in to it! Some interactive demos are at www.mjbc.ch.

Am now starting with AT91SAM7x (shame that it needs external PHY) 
which is a good step up in terms of performance and resources. 
Hopefully the Philips ARM equivalent will be available soon, and then 
the new Coldfire (a serious competitor in this segment) is high on 
the "to do" list.

As for the ENC28J60: When I saw the 250mA current consumption at 10M 
(if it is really true) my jaw also dropped. A standard CS8900A needs 
maximum 20% of this and a complete NE64 board running with 10M 
Ethernet requires only 100mA, including the processor at 50MHz: at 
100M the current consumption doubles.

I did also some tests with an LPC2106 using the NE64 as an Ethernet 
coprocessor via SPI, which is also an interesting possibility when 
more processing power is required - the NE64 can also handle the 
TCP/IP stack and leave the LPC2106 to concentrate on its main tasks. 
What is however a bit of a let down is the fact that the LPC2106 
doesn´t support DMA on the SPI interface and this can severely 
restrict the throughput - I concluded that this would also be a 
shortcoming if using the ENC28J60 with the LPC2106 (or equivalent).

My conclusions are:
- the ENC28J60 is an interesting device but until it is known to be 
stable and is optimised to have a sensible current consumption 
(possibly also 100M operation) I prefer the NE64 coprocessor solution 
via SPI.
- due to the lack of DMA support on the SPI, the SPI solution is not 
considered ideal with the LPC2106 (or equivalents).
- with the planned introduction of the Philips ARM device with 10/100M 
LAN it is probably better to wait a little longer for this
- Today I prefer the AT91SAM7x for mid-range embedded Internet 
applications (although I haven´t used the device much yet and may 
still have a suprise or two).
- For low-range embedded Internet applications the MC9S12NE64 is king. 
PCB design is extremely simple and a double layer board works fine, 
even when using all peripherals - see some photos at 
http://www.mjbc.ch/pics/uTasker/uTasker1_eng.html (if only SPI/LAN is 
required, it can almost fit under a standard RJ45 connector).

Regards

Mark Butcher
www.mjbc.ch