Recommended Ethernet MAC/PHY?

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Thanks to all who responded to the previous thread I started regarding
AVR+Nut/OS vs. ARM+Linux.  I have decided to go with an AVR (Mega128)
with external SRAM (32kB or 64kB, probably) and an external ethernet
MAC.  (I would still consider the AT91SAM7X, except that it doesn't
seem to be generally available yet.  If anybody knows where I can get
it, I'll give it a shot.)  For the OS and, more importantly, TCP/IP
stack, I'm still looking at Nut/OS, but have also expanded the options
to include Contiki and FreeRTOS (with uIP), or possibly just uIP with
no external OS.

But, there remains the question of which Ethernet chip to use.  I only
need 10Mbps, but I wouldn't mind running in 100Mbps mode.  (At 16
MIPS, I'm not going to be able to saturate even 10M, but it would be
nice to be able to put these things on a hub with 100Mbps nodes
without slowing everything to 10Mbps.  Some hubs can mix 10/100 right,
but not all.)  The RTL8019AS is apparently popular with hobbyists, but
it seems difficult to source (not carried by Digi-Key, for example).
Still, it seems like I can most easily find pre-written drivers for
this chip, so I wouldn't need to write my own.  (I've never written
Ethernet code, so I'm a little clueless about how it all works.)

Anybody have other recommendations?  My primary concerns are, in
priority order: (a) reliability, (b) getting the TCP/IP stack up and
running with a minimum of coding in one or all of the above-mentioned
OS environments, (c) minimizing the number of traces on the PCB, chip
footprint, and heat generation, and (d) being able to buy the chip
cheaply and reliably in small/moderate quantities (from half a dozen
for prototyping to a couple hundred for subsequent production).

Opinions on the three operating systems I mentioned (Nut/OS, Contiki,
FreeRTOS+uIP) would also be appreciated.  My primary concern here is
that it be as close to working out of the box (or rather, out of the
.tar.gz file) as possible.  It would also be nice to be able to
migrate easily to an ARM7 chip in the next generation.

And lastly, I don't suppose there are really a lot of differences, but
I'm also going to need to choose an external SRAM chip and one of
those shielded RJ45 jacks with integrated transformers.  If there are
any particular features I need to look for or gotchas in making these
selections, I'd appreciate a tip. ;)



Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

If staying with AVR was a done deal then my top choice for grafting
ethernet to the AVR was the Microchip ENC28J60. First I heard it was to
ship in July, then August. currently lists
September 15.

ENC28J60 has a lot of advantages, all on paper because the part isn't
shipping. Small pin count. Easy SPI interface. Reasonable price. And
will one day be available from every source currently selling PICs.

Re: Recommended Ethernet MAC/PHY?
David Kelly schrieb:

Quoted text here. Click to load it

I would also think in that direction.

Using "PC board mainstream" parts always have the risk that these
probably become obsolete half a year after design-in. Chips that are
targeted to industrial electronics normally have much longer lives.

Dipl.-Ing. Tilmann Reh - Elektronik nach Maß.

Re: Recommended Ethernet MAC/PHY?
Quoted text here. Click to load it

As you point out, running 10/100 let's you auto-negotiate the speed,
making your product more compatible.  You'll encounter some environments
that require 100Mbps connections, even if the device doesn't call for
it.  It also avoids problems with duplex mis-match, which causes
unreliable connections.  (Negotiating to full-duplex yields a
higher-performance connection too, though not a concern for you.)

Look at the ASIX AX88796l 10/100 ISA chip.  It uses a modified NE2000
driver (like the Realtek RTL8019AS).  You can source proto boards from (you'll find Mega128 drivers for the ASIX there too).

You can buy in small quantities direct from the manufacturer ($175 for
25x, +$30 S&H and ~$45 T&T fee [wire transfer fee charged by your

However, it's QFP-128 footprint (slightly wider than the Mega128), it
should run in 8-bit mode (but I haven't tried it); and it requires 5
address lines, 5 control lines, and 8/16 data lines.  Pulls 95mA
typical; runs cool to the touch.  (Microchip's SPI controller is really
the next step WRT fewer signal lines, but IIRC it also pulls 250mA at 10Mb.)

For the jack, Bothhand NU1S041C-434 RJ-45 w/ magnetics & 3 LEDs is very
popular.  $3.50 each in tubes of 28 + $10 S&H from .  (Some others are Delta, Pulse, Bel Fuse,
HALO, MagJack, Tyco, Molex, etc.)


Re: Recommended Ethernet MAC/PHY?
Why the Mega128???

Let's look at silicon costs...

Mega 128 $8.00
SRAM       $1.50
Mac Phy  $4.00
Ethernet Jack $1.95

Total Silicon 15.45

Freescale/Coldfire 5270 7.95 (We currently use the 150Mhz version $9.54)
512K Flash                1.25
10/100 Enet Phy            1.50  
10/100  Etyhenet Jack   1.95
Total Silicon                12.65

I'd personally ad 2Mbytes of SDRAM to make things easier
Total Silicon with SDRAM $14.15

over $1.00  cheaper than the MEGA 128 solution.

This gives you a far more capable unit.
100Mhz 32 bit CPU,  512K flash ,2M bytes of SRAM, 3 uarts, CAN, I2C, SPI, 16
10/100 Ethernet.

If you need A/D from the Mega then substitute a freescale 5282 for the CPU and

We offer turnkey ready to use modules based on this part
You can start your software development today.

We will sell you the design, hardware, software tcp, tools,. compiler linker
with full source etc..etc... . so you can produce your own modules for $24,500
This is a site license for an unlimited number of designs, with no royalties.
This price includes a design review of your first hardware design based on our
If you just wanted to produce a clone of our modules, the PCB designs are even

If you have realistic costing for your engineering time you would
be hard pressed to do a hardware design and port a tool set, RTOS and tcpip
stack to
any design for 24K.

As a general comment, some people are scared by the word RTOS, it's there and it
keeps all
the TCP/IP services running in the background, but for your own programming you
don't need to
use it at all, just write your code in the way you are accustomed, a single
threadof execution
with interrupts providing any necessary scheduleing.



RTOS example:


Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

It doesn't make sense with AVR, if you need ethernet.

Quoted text here. Click to load it
Quoted text here. Click to load it

AT91SAM7A,7S or 7X are just as good.

AT91SAM7X seems to be your best choice.  If you are concerned about 7X
availabilty, goes with 7A or 7S first.  If you are starting your
project soon, perhaps you can get the 7X when you are ready for it.
Switching from 7A or 7S to 7X is a lot easier than from AVR to ARM.

Re: Recommended Ethernet MAC/PHY?
Quoted text here. Click to load it

Because it's what I'm familiar with.  Bad reason.

Quoted text here. Click to load it

Upon further investigation, I have come to agree.

Quoted text here. Click to load it
Quoted text here. Click to load it
and Flash.
Quoted text here. Click to load it

I am convinced.  I've been looking into the availability of the
AT91SAM7X, and Atmel claims the distributors will have them Oct 1.
I've got calls into the distributors to see if that's for real.  Only
Digi-Key has responded so far, and the responses was something along
the lines of "Huh?  Ain't never heard of it."  We'll see if anybody
else comes through.

I can probably wait until mid-October to get the part.  But then I
have another problem -- I need a cheap Ethernet PHY (no MAC, since the
7X has on-chip MAC).  And the problem is that the low-volume suppliers
I usually use (Digi-Key and Mouser) have pretty poor selections of
PHYs.  (Digi-Key is charging ~$8+ for a simple 10/100 PHY... seems
outrageous.)  In fact, most of the parts I've been looking for during
this project (which is a bit more complex than things I've undertaken
before) are expensive or non-existant in Digi-Key's catalog, so
perhaps it's time I branch out to other suppliers -- any suggestions
(of suppliers and/or parts)?



Re: Recommended Ethernet MAC/PHY?
Quoted text here. Click to load it

How many are you trying to build?
(Do you just need samples or 100.1000.10000?)

We have had good luck with the Davicom DM9161
Probably at least a 100pc minimum buy.

Micrel has some new very low cost PHY chips as well...
you could probably get dsitributor samples....
(We are just starting to use some of these)

Lastly try the DP83847ALQA56A-ND $5.70 Q1 from digikey.
It is a fine PHY, but  be aware that placing the LLP56 package on a PCB is a


Re: Recommended Ethernet MAC/PHY?
Quoted text here. Click to load it

Initial prototype run of 5 units, then a first production run of about
50, and then (if all goes well), subsequent runs of 100-300.  The
larger runs are easy, but how do I get small quantities for

Quoted text here. Click to load it

I've seen Davicom mentioned, so I've been looking for anybody who
carries Davicom, with no luck... where can I get them in the US?

Quoted text here. Click to load it

Yeah, the prototypes will be hand-soldered by yours truly, so leadless
packages are probably not such a good idea.  How do the pros handle
prototype assembly of things that can't be hand-soldered?  I'm not a
pro, just an amateur hack who got talked into doing this project.  I
guess that makes me a pro now, but I don't feel like one.  In
particular, trying to navigate the sea of manufacturers, parts, and
distributors is getting a little overwhelming.


Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

We simply order the prototype board with the part mounted.  Dm9161AE
(TQFP 48) is not a problem for the prototype shop.  For productions,
they are $2 to $4 each, depends on qty.

Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

I just got a quote from the shop.  They can provide the Dm9161AE
(ethernet phy) and mount on the prototype board for $5 additional.  The
prototype boards are $5 to $10 each, depending on size.  Mininum order
of $50.  See:

Re: Recommended Ethernet MAC/PHY?
Quoted text here. Click to load it

linnix, Randall,

Were you able to find a US distributer for direct purchase/sample of th


This message was sent using the comp.arch.embedded web interface o

Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

We are getting some for $3 each.  How many do you need.

Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

There are distributors with samples right now...
If you download the evaluation kit manual ,then there are some schematics
with a Davcom PHY.
You probably want to use RMII to save pins.
If you need industrial temp range, then the Davicom part will not cut it but
a micrel part cn do
RMII + industrial.

Quoted text here. Click to load it

Re: Recommended Ethernet MAC/PHY?

Quoted text here. Click to load it

SAM7X samples has been seen!

A. P. Richelieu

Site Timeline