Derek H

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7 years, 3 months ago.

Is there a max length for CAT5 ethernet cable on mbed lpc1768

I'm currently prototyping Ethernet on the mbed lpc1768, on my own custom pcb i'll be connecting the ethernet cable directly to RD- RD+ TD- TD+ pins and not via a RJ45 jack, do I need to be concerned over the length of my CAT5 cable? Cable will run from my mbed to a pc, approximate distance is 6ft, is that too long?

Thanks for any advice

1 Answer

Wim Huiskamp
7 years, 3 months ago.

Direct connection between the mbed lpc1768 and an ethernet cable to a PC can be done see here, but is not recommended. You should really have the transformer/magnetics in between the ethernet phy and the cable. Most rj45 jacks have magnetics integrated. You will also need a crosscable or crosswire between the mbed and the PC rather than a straight cable that you would use for connecting to a switch or router. Do a search on mbed for rj45 to find more info.

Accepted Answer

Thanks, this is all new to me so any advice is appreicated. So would this connector work for me? http://www.digikey.ca/products/en?keywords=626-1391-ND&WT.z_slp_buy=conec_industrial-connectors

posted by Derek H 31 Dec 2016

The link you have above is for a heavy duty RJ45 socket. Not sure if your operating environment needs that kind of socket, but you may also need to look at power/noise conditions in case you do. The socket does not have magnetics, so you would still need to add a separate transformer. Here is a link to sockets with an integrated transformer, that would make things easier.

posted by Wim Huiskamp 03 Jan 2017