On Thu, 13 Dec 2007, Edwin Olson wrote:

> http://www.blisstonia.com/eolson/lpc_prog20071213.tgz

Thanks. I don't have any near-term applications, but the idea itself is
pretty nice (and now, it's out there in case others would like to use
yours).

-Kenny

--
Kenneth R. Crudup Sr. SW Engineer, Scott County Consulting, Los Angeles
O: 3630 S. Sepulveda Blvd. #138, L.A., CA 90034-6809 (888) 454-8181

An Engineer's Guide to the LPC2100 Series

I have sampled the DS2502P-E48+ from Maxim IC. This will be the best
solution. I only have about 50 prints/year. The IC is only 1.30$, so
this is the cheapest is most simple to implement solution.

Thanks all

On Thu, 13 Dec 2007 16:12:50 -0000, you wrote:

>My project is not one time, it's for production. So taking the mac of
>an existing PCI card won't work for me.
>
>Taking the first MAC address that comes in won't work neither, because
>I have to set my MAC address before I can init my TCP stack (wich is
>TCPNet from Keil)
>
>Is there not an unique number in the cpu of lpc? Can I perhaps just
>make a pointer, and not initialize it, then just take the value of it.
>Would this data be random or will it be '0' if I don't use this space
>yet.

It would likely always initialise to the same value.

>Are there no other really random making functions in C???

It's a hardware problem, not a language one.

If it's for production, shouldn't you really be buying a proper allocation of addresses ?

karelvergauwe wrote:

> the same numbers (in the same sequence). Then I found I should seed
> them with the srand(seed) function. But this isn't any better because I
> don't have a unique seed number. Normally the current time is used as
> seed number. But When I start I don't have any time...

sometimes a negative number works for this...
Or a timer.

--
Ciao, Dario

Dallas Maxim makes an IC DS2502 that supplies a GUID 48 bit address and is used as a MAC on the the DS80C400 micro-controller.
It adds cost but takes the burden of obtaining IEEE addresses and managing them out of your hands.
-----Original Message-----
From: l... on behalf of Edwin Olson
Sent: Thu 12/13/2007 3:56 PM
To: l...
Subject: Re: [lpc2000] Generate a unique (local) MAC address

> Huh. I like this idea. May I stea^H^H^H^Huse it?
>
http://www.blisstonia.com/eolson/lpc_prog20071213.tgz

Run with --help for info; you want the --write-id options. The
--write-id-signature is used to write a magic value; this serves two
functions. First, allows you to double check at run-time that a unique
value HAS been written. Second, the program will not write a new MAC
over an old one if the signature is there-- that way, your MAC doesn't
change every time you reflash.

Note, it sounds like the device ids might have changed with the new MCU
revs-- you might need to update the database (devices.c) (send me a diff
if you do, please.)

There is a block of MAC addresses that are locally administered and do
not require paying a fee. Very handy for pre-production. However, an
actual product should come with a globally unique MAC.

-Ed

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> Huh. I like this idea. May I stea^H^H^H^Huse it?
>
http://www.blisstonia.com/eolson/lpc_prog20071213.tgz

Run with --help for info; you want the --write-id options. The
--write-id-signature is used to write a magic value; this serves two
functions. First, allows you to double check at run-time that a unique
value HAS been written. Second, the program will not write a new MAC
over an old one if the signature is there-- that way, your MAC doesn't
change every time you reflash.

Note, it sounds like the device ids might have changed with the new MCU
revs-- you might need to update the database (devices.c) (send me a diff
if you do, please.)

There is a block of MAC addresses that are locally administered and do
not require paying a fee. Very handy for pre-production. However, an
actual product should come with a globally unique MAC.

-Ed

On 13 Dec 2007 at 16:12, karelvergauwe wrote:
> My project is not one time, it's for production. So taking the mac of
> an existing PCI card won't work for me.
>
> Taking the first MAC address that comes in won't work neither, because
> I have to set my MAC address before I can init my TCP stack (wich is
> TCPNet from Keil)
>
> Is there not an unique number in the cpu of lpc? Can I perhaps just
> make a pointer, and not initialize it, then just take the value of it.
> Would this data be random or will it be '0' if I don't use this space
> yet.
>
> Are there no other really random making functions in C???

If you are producing lowish quantities, then it might be worth using a 1-wire
chip from Maxim that contains a unique address in each chip. They have one specifically
programmed to provide a legal and unique MAC address.

Regards
Anton Erasmus
--
A J Erasmus

On Thu, 13 Dec 2007, Edwin Olson wrote:

> I modified my flash-writing application to write a few random bytes to
> the end of flash. I can then read these at run time. This approach is
> nice because the same device will always boot up with the same MAC
> address, so DHCP and other things will work properly.

Huh. I like this idea. May I stea^H^H^H^Huse it?

-Kenny

--
Kenneth R. Crudup Sr. SW Engineer, Scott County Consulting, Los Angeles
O: 3630 S. Sepulveda Blvd. #138, L.A., CA 90034-6809 (888) 454-8181

--- In l..., "karelvergauwe" wrote:
>
> My project is not one time, it's for production. So taking the mac of
> an existing PCI card won't work for me.
>
> Taking the first MAC address that comes in won't work neither, because
> I have to set my MAC address before I can init my TCP stack (wich is
> TCPNet from Keil)
>
> Is there not an unique number in the cpu of lpc? Can I perhaps just
> make a pointer, and not initialize it, then just take the value of it.
> Would this data be random or will it be '0' if I don't use this space
> yet.
>
> Are there no other really random making functions in C???
>
> thx
>

The entire ethernet protocol is based on UNIQUE MAC addresses. They
absolutely need to be unique on the LAN.

Any random number you pick is just as likely to be a duplicate MAC
address as any other. Once that duplicate MAC gets to a router there
is no way to sort the traffic.

Since you are developing a commercial product, why not just buy a
block of MAC addresses:

http://www.denx.de/wiki/DULG/WhereCanIGetAValidMACAddress

Richard

karelvergauwe Wrote
>My project is not one time, it's for production. So taking the mac of
>an existing PCI card won't work for me.

To reinforce the other replies. If it's for production the ONLY legitimate
way is to buy a set of valid MAC addresses. Globally unique MACs are how
ethernet products are guaranteed not to interfere with each other.

It's part of the cost of doing business.

Robert

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