Web 51 - MAC addresses

Every device connected to an Ethernet network can be directly addressed, having a unique 48-bit MAC address. Out of those 48 bits, first two are reserved for address type identification. First bit states whether it is an address of a station (0) or a group of addresses (1). Second bit is more interesting for us; it states whether this is a centrally assigned address (0) or an address assigned locally within a single network (1). Several communication protocols utilize the second option for their addressing (for example, an IP address can be directly used in this field).

How to get a MAC address for Web51?

First option, or rather a dream^(*), is to join manufacturers such as Intel or 3Com and get a designated subrange of MAC addresses - registration details are here.
Second option is to use a random number for address. This method is fair as long as an address from the local address space is used. Since the probability of ending up with two equal 48-bit addresses on the same network is very low, this method is widely used - especially by hobbyists.
Third option, used by the author, is to use the address of another device, that certainly does not exist. In this case, such a device would be the respective network interface card that was cannibalized for its components.

Determining the MAC address of a network interface card:

Insert the card into a PC and use appropriate utilities to read its MAC.
Use a prototype version of WEB8051 and read the MAC address with packet drivers. However, since it is a PnP adapter and WEB8051 is compatible only with properly configured cards, sometimes the card must be configured in a PC.
Read the MAC from its onboard EEPROM.

Configuration memory of RTL8019

Meaning of individual values is detailed in RTL8019AS documentation; however, here is an example - read from a Micronet card, serial #93700936:
(00H): 10 00 90 00 00 00 E8 EE 10 33 20 20 20 20 20 20  ..É...##.3      
(10H): 20 20 41 D0 00 60 33 10 EE 00 FB 0A 10 10 82 21   A#.`3.#.#...é!
(20H): 00 4E 45 32 30 30 30 20 50 4C 55 47 20 26 20 50  .NE2000 PLUG & P
(30H): 4C 41 59 20 45 54 48 45 52 4E 45 54 20 43 41 52  LAY ETHERNET CAR
(40H): 44 00 16 00 00 95 19 02 00 1C 41 D0 80 D6 47 00  D....Ó....A#È#G.
(50H): 00 02 E0 03 20 20 23 38 9E 01 79 09 FF FF FF FF  ..#.  #8Ø.y.    
(60H): FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
(70H): FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
So, in more detail:
(00H): 10 00 90 00
First four bytes contain configuration data for registers CONFIG1 to CONFIG4.
(04H): 00 00 E8 EE 10 33
Next 6 bytes contain the MAC address, here 00-00-E8-EE-10-33.
(0AH): 20 20 20 20 20 20 20 20
Clearly, Micronet does not use Product ID.

PnP data follow: first is PnP Identifier consisting of two parts:
(12H): 41 D0 00 60
Vendor ID
(16H): 33 10 EE 00
Serial Number
(1AH): FB
Checksum of the PnP Identifier (Vendor ID and Serial Number).

PnP Identifier is followed by PnP Resource Data:
(1BH): 0A 10 10 82 21 00
(21H): "NE2000 PLUG & PLAY ETHERNET CARD"
(41H): 00 16 00 00 95 19 02 00 1C 41 D0 80 D6 47 00
(50H): 00 02 E0 03 20 20 23 38 9E 01 79 09

^(*) Well, after some time has passed, it is no longer a dream. Web 51 may get its own MAC address space soon.

Details about MAC addresses:
^(#) For information on how to use MAC addresses, see IEEE Std 802-1990, Overview and Architecture.

To apply for an Organizationally Unique Identifier for building a MAC address, contact the
Registration Authority
IEEE Standards Department, P.O. Box 1331
445 Hoes Lane
Piscataway, NJ 08855-1331, USA
tel +1 732 562 3813 fax +1 732 562 1571
URL:http://standards.ieee.org/.