Smallest IP Target Device?

Donimo asks: "I have seen many tiny ethernet loopback jacks and keyfobs, and I'm looking for the smallest IP equivalent for my toolkit. It just needs to plug into an RJ45 ethernet port and respond to ping. If the IP address is configurable, so much the better. I have looked at small IP print servers, and I could probably knock one up from a Gumstix but these are comparatively expensive solutions. Any ideas?"

Comments

picotux

[ach1000]

http://www.picotux.com/

Just a ping

[mnmn]

I have seen PIC microchips connected to something like an RL8139AS or cs8900, PHY and jack. The pic16xxx is the simplest device that can do the ICMP/IP and have enough pins to talk to the ethernet chip. The atmel devices are alternatives, like the attiny maybe. These chips are sub-$1, but remember the ethernet chip is at LEAST $10. Under $20 devices are possible where they have dedicated IP addresses and can send/receive UDP, raw IP and simple ICMP like ping. TCP will require more complexity and ram. Linux is way too big if youre talking about the simplest devices... other RTOSes fill that niche if you intend to have full TCPIP. In that case, look at micrium ucos, ecos, freertos and other similar devices.

Will be interesting to see if someone can use a fast 8-bit chip to act as an ethernet chip too (bitbanging ethernet). Will have to be well over 10MHz and should be able to do ARP first. In that case, sub-$5 devices are possible with chips with fewer pins, with the BOM quite possibly under $2 (jacks, chip, board, phy in qty). But these will be far less reliable.

You don't really ping yourself

[klossner]

Pinging yourself doesn't test your hardware. When you ping your own IP address, the network stack handles the response internally. Nothing goes out on the wire.

Having a real device with a distinct IP address lets you send and receive actual packets and so verify that the PHY and MAC layers are working.

XPort

[nebbian]

What you're probably after is an XPort in a box with a battery. These devices use 3.3V, have a full TCP/IP stack, a web server, some flash memory, all somehow shoehorned into an RJ45 connector. Yep that's right, the thing is about the size of an RJ45 connector! If it runs at 3V you could probably run it off a 3V lithium battery, of not then use 6V with a 3.3V low power regulator.

These retail for around $30 in bulk, with a bit of digging you should be able to get one for less than $50 I'd think...

With a switch, battery, regulator and heatshrink around it, it will still be quite small enough to lose easily :-)

hth,
Ben