I think they are based on an Arduino with the ENC28J60 network shield, but don't really know for sure. (Because, honestly, I might as well be speaking gibberish when I say these things, since I don't know what I'm talking about.)
Now, I know I got what I paid for. I get it....
Here is my question:
Although the device allows me to change the IP address via web interface, it appears they all have the same MAC address and therefor are dropping connection with my network.
I have no idea how to reprogram these, or if it is even possible. The seller is less than helpful. (I know, read my disclosure about paying for what you get.)
I have never programmed and wonder if it is possible, assuming these are Arduino-based, to read the sketch from it, adjust the MAC address via code in the sketch, then reload the adjusted sketch on the device?
Although I am a reasonable do-it-yourself techie, I have no experience with this (hence the attempt to buy pre-configured devices), so any help really needs to be specific, step-by-step and will be GREATLY appreciated. Thank you.
Actually, a MAC address is supposed to be guaranteed to be globally unique by the manufacturer. Microchip is the manufacturer of the chip you describe and according to their datasheet, the MAC address is globally unique (as one would expect it to be).
If yours are not unique, it would appear that you don't have a microchip product but rather a cheap copy where they don't even bother to program each with a globally unique MAC address.
There may be an EEPROM that could be replaced/reprogrammed but that would seem to be a bit radical.
I agree, a MAC address is like DNA. It differentiates between each device unless the maker of the IC is unreliable. If they truly have the same MAC address, I would advise you not to but from that manufacturer unless necessary.
What library are you using? You should be able to set each enc28j60 with a unique mac with the begin function call.
Here is a common library used for the enc28j60.
I have no idea how these things are programmed. I bought them on ebay, pre-programmed. I'm not even sure there is a spot on the board to make a connection for programming.
I think you are on the right path with your comment, I just don't have enough knowledge to answer the question.
As I see it, there are three challenges I am facing:
Is there a terminal on the board to allow for connection to a pc for programming purposes? (Assuming you don't do it right through the RJ45, I'm wondering if one, or more of the solder pads are for this purpose.)
If #1 is answered affirmatively, is there a way to read the sketch off of the device, as is? Or, is there already a sketch available that achieves the same results?
Can the MAC address of the ENC28J60 be adjusted via programming? To that, the answer seems to be yes, based on your post.
Then, I just need someone to help me through the process...
Not for everyone, but if you have a smart enough network architecture and you can create separate VLANs then you can have each object in its own VLAN and there should be no conflict.
(Current switches do have separated FDB tables per VLAN - Older switches can have one common FDB table for all VLAN so that would not work)
(If you don't know what a VLAN is, don't even start. To investigate - you are better off replacing your devices)
So I wonder if I am understanding you correctly. Could I replace the 11AA02E48 on one of these boards and that might give it a new MAC address? Is it probable, or even possible that other coding has been programmed to it and that would need to be transferred to the new chip?
Looking at the eBay pics, since I can't get to the boards at the moment, it looks like the UC labeled u4 could be a 11AA02E48.
Can you read the markings on the chip? The eBay listing says "16bit" but the picture looks like it says "Nuvoton", which is a combination that doesn't seem to exist. (Nuvoton has 8bit 8051-like chips, and 32bit ARM chips.) Arduino code doesn't run on any 16bit chips, nor on any Nuvoton chips, so the chances that this device is running Arduino code seem pretty slim.)
Usually widely sourced boards like this are based on some "reference design", and you can find documentation of the original. In this case, though, I can't find anything (some slightly better photos - definitely a nuvoton chip, but I can't tell which one.
To earlier posters:
Thanks for the thoughts. I considered VLAN options, but I run unmanaged switches, so that doesn't seem likely to work and will probably cause me more headaches than good. And, since this is just a hobby project, I am not going to invest in managed switches, even though they can be found for under $30.
And, I checked my router. No option to turn off MAC authentication... at least that I could find.
As for the chip set, I will get a good look at a board after work tonight and see what the chip numbers are. I will post that as soon as I can.
