I came across a device that used 3 LEDs to indicate the speed of the Ethernet (10 base, 100 base, no connection). I want to build my own device. I don't want to use a microcontroller. I would also like to include a loop test where I can turn the signal off and slap the loopback on the other end and check continuity. That part is easy. Checking the speed is what has me stumped. Any ideas?

 

I doubt would be very easy. many products can do this, but likely need at least a lot of ICs. I would think almost need a micro to do this. the way these testers work is by actually making data of different amounts and measuring resulting delay. you would most likely also need firmware too. most of the OSI model would also need to be used (this relates from firmware, addresses (not needed here) and physical interfaces.
be better just getting a fluke or similar tester.

 

Even a sub $10 hub or switch will do this, you don't need Fluke.

 

Thanks for the replies but I'm not going to test Ethernet ports with a hub or a switch. If I were to buy something, I would buy what I mentioned in the OP. Your missing the scope of the post. I WANT to build my own. I imagine I would have to sample the signal and then compare it.

 

A 1000/100/10 connection is negotiated when the connection is made, so you can plug a high speed device into something slower and it'll match the slower connection. Switches and hubs contain very sophisticated electronics, not something you can cobble together with some resistors and LEDs. Try reading through the Microchip ENC28J60 datasheet to get an idea of the complexity of Ethernet.