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Ethernet PHY Accessory board - Page 3 — Parallax Forums

Ethernet PHY Accessory board

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  • I got mine today. It works! Thanks!

  • Two months have passed now, so I think it's time to bring this topic to the front, again...
    Has anybody used the boards for anything?

    I found out that the 24AA025E48 chips in SOT23-5 packages are now sold out worldwide. There are still some available in SO-8 package but as Microchip seems to have severe supply chain problems I would no longer count on that. The 24AA025E48 is very special as it offers an extra address pin which allows use of both, a normal boot EEPROM and a MAC rom on the same SDA/SCL lines which is necessary for my P1 solutions. But for the P2 accessory board we are not restricted to that. So we could simply use a standard 24C02 which is available from plenty of manufacturers.

    But I don't know how "safe" it is to use just a random (self generated) number as MAC address.

  • evanhevanh Posts: 13,574

    Microchip's problems will most likely be from the toilet paper hoarders. There'll be a rebounding glut soon enough.

  • @ManAtWork said:
    But I don't know how "safe" it is to use just a random (self generated) number as MAC address.

    You mean legally?

  • Yes, I mean the assignment of MAC numbers isn't a national law, just a loose agreement between implementors of the ethernet standard. I haven't signed anything so they can't sue me for violating any contract. The chances that a doublicate number will cause any conflict is rather low. As long as I don't claim the products fulfill a standard or use a foreign trademark I shouldn't get in trouble, I think.

  • ke4pjwke4pjw Posts: 685
    edited 2022-07-11 20:28

    I agree 100%. It is a legal nothingburger, so long as you don't misrepresent the product.

    This is how I solved the problem of no MAC for the W6100. First, I checked to see if there is a config on the the SD card. The config holds the MAC, so it doesn't change unless you wipe the config. If no config was found, I would generate a MAC, and save the config. I used the Wiznet OUI 00:08:DC and then three random octets using the PRNG. That way, it was easy to identify the device by manufacturer. The PRNG has never generated the same MAC though my testing.

    I think using an OUI of manufacturer of the chip and random for the specific NIC works well.

  • avsa242avsa242 Posts: 340
    edited 2022-07-11 20:14

    I started looking at mdio and rmii back then to understand they work, in order to make a driver in my style (I think I tried the files you posted and was able to get them to work also? I don't remember for sure though). Between that and learning TCP/IP for another mac/phy chip I got a bit burnt out on networking in general, so gave it a rest for a bit. I'll probably come back to it soon though.

  • ElectrodudeElectrodude Posts: 1,499
    edited 2022-07-12 13:29

    I have a driver for this board that does UDP, but I ran into something of an architectural roadblock when I realized that I had to add a proper timer scheduling subsystem to support TCP, DHCP, a complete ARP implementation, and pretty much any other reliable protocol. I'll eventually get back to working on this once I actually need it for the thing I'll need it for.

  • Thanks @ke4pjw , that was exactly wghat I've also planned. Take the first 3 bytes (manufacturer ID) from the Microchip 24AA025E48 I've already bought many 1000s of so I don't step on somebody else's feet. The remaining 3 bytes can be a random number to minimize the possibility of conflicts with existing devices.

    Thanks @avsa242 and @Electrodude for the status report. My own work has also beem delayd a bit recently due to other software development on the PC but I will hopefully continue with the P2 ethernet project soon.

  • I'd like a few more of your PHY accessory boards. Can you post the design on OSHpark or share the gerbers or design files here or something? Thanks.

  • I'm a bit busy at the moment but I've just ordered another 20 boards from JLC because I also got requests from others. If you want to order from OSHpark, I've attached the gerber files for the Panel as they were produced last time (see post #34). I've also made a slightly modified layout with the SMD pin header as Parallax uses them for the accessory boards. I've attached the Eagle file. If you need anything else (BOM, placement file...) please say so.

  • I wonder if you could just use some obscure manufactorer's MAC prefix and add a running number or a random one. There must be MAC addresses that belong to some long forgotten ethernet cards that are not sold anymore for a long time now.

  • @Simonius said:
    I wonder if you could just use some obscure manufactorer's MAC prefix and add a running number or a random one. There must be MAC addresses that belong to some long forgotten ethernet cards that are not sold anymore for a long time now.

    You can use a 'private' mac-address:
    https://www.oasys.net/fragments/identify-private-macs/ OR
    https://superuser.com/questions/907827/private-mac-address OR
    https://serverfault.com/questions/40712/what-range-of-mac-addresses-can-i-safely-use-for-my-virtual-machines

    Those ones are consider to be under your control

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