I2C devices with unique identifiers.

I use the Microchip 25AA02E48 in several products. It's SPI but the

Thanks, that's exactly what I need.

-- Roberto Waltman

Dallas did a good job with the one wire parts in general and only using one wire is a great thing. But they don't seem to be price competitive for who knows what reason. I seem to recall the one wire part that is the least expensive is one of their eeproms. I'm pretty sure it is lot more than a quarter. Heck, sometimes it is cheaper to emulate a one wire part with an MCU, but then you have to do your own serial number programming!

Rick

Nowadays a lot of MCUs come with a unique serial number.

I know of a few, such as NXP's LPC1311. But the processor in this project does not have this feature. (Can not change that)

-- Roberto Waltman

Does the board have a flash? Then maybe you already have a 64-bit unique ID available.

Leo Havmøller.

Thanks, I am aware of those and no, the only flash is the CPU's internal memory.

-- Roberto Waltman

I second the recommendation, I use both flavors of these guys a regular basis. As easy to use as any serial EEPROM and cheap.

How about using a uC with built-in unique ID? E.g. STM32F?

Bye

That's very interesting info on the 24AA025E48. We currently use a STm24cxx256 part on our boards both to store a MAC address (and a bunch of other programming information). We bought a block of 4096 addresses from the IEEE, but keeping track of them all and having to program each boardset prior to use is something of a pain.

While we need far more than the 2kbits available on the 24AA025E48, it might be very much worthwhile adding one just for the MAC. Reading the datasheet, it looks as if this is a valid IEEE MAC address as microchip have registered for an OUI. Given that and the low price of the parts, I might well be pushing for one of these on the next rev of our board as it cuts out a programming step.

Thanks for the info!

--------------------------------------- Posted through

Valid for a new design. This is a respin of an existing product, and the CPU (untouchable) does not have an ID.

-- Roberto Waltman

It's trivial to use your own OUI with these parts. Just slam yours in the 1st 3 bytes when you program the EMAC block

Wait a minute, they are doing a respin and the old uC is untouchable??? Hand them a flashlight and a crowbar. They are in dire need. Even in aerospace and medical any respin is effectively a new design. New pass = on ALL qualifications.

?-)

I understand that perfectly. I don't know why they are doing a board spin, but they don't want to touch any code they don't have to. Using a different MCU chip can wreak havoc on code if it turns out to have unsuspected hardware dependencies.

"There's many a slip, twixt cup and lip."

Rick

Precisely. The new and old boards share 80% of the peripherals, and that means a lot of the code is already written, tested and known to be reliable, if we stay with the same CPU.

-- Roberto Waltman

a=20

Well alrighty then. Family compatible could be potentially acceptable then. Depends a lot on just which peripherals are onboard the MCU.

?-)