HDMI on Screened Cat5e

Cat 5e cable has four twisted pairs. The important high speed data and clock for HDMI uses four twisted pairs of similar spec. You do need to use the Screened version of Cat5e (STP), not the more common UTP. Two Cat5e cables are needed.

You need

  • 1 x Argos 0.75m HDMI cable or similar to cut in half
  • Twice the distance you want of Screened Cat5e as two cables are needed
  • Sharp knife
  • Cheap meter or buld & battery continuity tester if the HDMI cable seems different.
  • Soldering iron & solder
  • Insulation of heavier wire, heat shrink sleeve and/or PVC tape.
  • 4 pieces of wire to connect screens (2 at each end)

hdmiI bought a €7 0.75m HDMI cable from Argos and checked it out with a €5 multi-meter for continuity and wrote the colours down in the table below. You need a second Cable for all the low speed signalling. The Screen of the cable with the 3 data signals and clock signal connects to all four screens of the twisted pairs in the HDMI cable. No Balun is needed as the signals are already "balanced". Don't connect this screen to the overall screen of the HDMI cable.  Connect the screen of the second Cat5e cable to the overall HDMI screen. The braid on the HDMI cable was aluminium which doesn't solder, but there was a bare copper wire too, which was soldered to the Cat5e screen wire after cutting off the excess aluminium foil screen.

It's a good idea to check the pins 17, 18 and 19 with a meter on Ohms or battery and light bulb to make sure the Ground (17), +5V (18) and Hot plug (19) wires are correct colours. The four twisted pairs in the HDMI can connect to any pairs of the 1st cable as long as both ends are the same. Diagram is view looking into open end of the plug, not the socket or inside rear.

The pairs below are suggested. The most important thing is that both ends are the same and that use one 1 wire of a pair for SCL  (DDC clock, pin 15) and the other wire of same pair to pin 17 (ground) . Similarly with SDA ( DDC data pin 16).

Some heat shrink sleeve would be best over the soldered connections. I just used tape and cut pieces of plastic stripped of heavier wire to slide over the solder joints.

You can buy a wall plate on line (mislaid URL!) that has HDMI socket on front and 2x RJ45 sockets on rear.

All wires in first cable (3 x data pairs and 1 x clock pair) must be same length connection.

Distance Possible

According to the HDMI spec, it seems Screened Cat5e should be good to over 15m, maybe more. At full 1080p + audio, a regular bought HDMI repeater or Cat5 HDMI extender box does 45m max and costs about €70. The distance I did including the HDMI tails was about 8m. I had some offcuts of STP Cat5e, so total cost for me was €7 approximately. You can double the distance to over 30m or more by putting an HDMI repeater in the middle of the cable. Possibly a 2nd repeater would allow 45m to 50m.

 

Type A HDMI connector ( grn & whi are twisted pairs)



Pin



HDMI Signal


Argos 0.75m


Cat5e Colour


1st Screened CAT 5e cable

(screen to HDMI 2,5,8,11)

1

TMDS Data2+


grn

Orange with white stripe

2

TMDS Data2 Shield

  pink foil

screen

3

TMDS Data2-

 
whi

White with orange stripe

4

TMDS Data1+

 
grn

Brown with white stripe

5

TMDS Data1 Shield

  silver foil

screen

6

TMDS Data1-

 
whi

White with brown strip 

7

TMDS Data0+

 
grn

Green with white stripe

8

TMDS Data0 Shield

  green foil

screen

9

TMDS Data0-

 
whi

White with green stripe 

10

TMDS Clock+

 
grn

Blue with white stripe

11

TMDS Clock Shield

 ( Red foil)

screen

12

TMDS Clock-

 
whi

White with blue stripe


2nd Screened Cat 5e cable

(screen to HDMI screen)

13

CEC ( control)

white

Blue with white stripe

14

Reserved (N.C)

purple

White with blue stripe

15

SCL  (DDC clock)

yellow

Green with white stripe

16

SDA ( DDC data)

orange

Orange with white stripe

17

DDC/CEC Ground

pink

White with orange stripe

White with green stripe 

18

+5 V Power (EDID/DDC)

red

White with brown strip 

19

Hot Plug Detect

grey

Brown with white stripe

CAT5 Plugs

Normal wiring scheme for RJ45 plugs if using wall plate


Pin


Name


Description


EIA/TIA 568B cable colours

1

TX+_D1

Transmit Data+

White with orange stripe

2

TX-_D1

Transmit Data-

Orange with white stripe or solid orange

3

RX+_D2

Receive Data+

White with green stripe 

4

BI+_D3

Bi-directional+

Blue with white stripe or solid blue

5

BI-_D3

Bi-directional-

White with blue stripe

6

RX-_D2

Receive Data-

Green with white stripe or solid

7

BI+_D4

Bi-directional+

White with brown strip 

8

BI-_D4

Bi-directional-

Brown with white stripe or solid brown

 

Some photos

HDMI-join2

Two Screened Cat5e on an HDMI cable in Radio Shack

HDMI-join

Two Screened Cat5e on an HDMI cable rear of HDTV in Living room

dvbviewer-tuners

DVB Viewer with 2 x DVBS2 PCI cards and 1 x Mobi DTV dual DTT USB stick on PC

Photographed on LG 42LD450 HDTV.

(The MobiDTV stick has proved unreliable and the supplier is gone. Do not purchase)

PC VGA graphics running at 1920x1080p50

dvbviewer-tuners

Regular Keyboard, Mouse and VGA monitor in the Radio Shack on the PC.

DVB viewer on PC OSD activated on LG HDTV 1920x1080p50

dvbviewer-tuners

PC has 28E, 19E, 13E, 9E, on 2 x DVB-S2 and Soarview on 682MHz from Woodcock Hill

42" HD TV (LG 42LD450)

A Long USB cable run into house also with Logitech Wireless keyboard/Mouse dongle, which can wake the PC from Standby. A 3rd Cat5e cable (UTP) now carries analogue audio (the HDMI audio works fine) from PC sound card and extend the IR eye plugged into one Sat card.

Remote Control

There is a Technisat remote. In the past I have run an IR eye over 2 pairs on Cat5e for 25m. One pair is ground and Power and the other pair is signal and ground into the miniature 2.5mm stereo jack. DVB viewer can "learn" commands from any RC5 type remote. The Remote can put the PC in standby. Sadly there is a "resume" bug where you need to use mouse to go into Input setup to wake the IR remote eye. Or something. I have also wired a RS232 plug with capacitor, two resistors, 5.1V zener and 2.5mm stereo jack to use WinLIRC instead.

Cat5e Cable used for PC line or Speaker out and IR remote Eye in

Function 2.5mm jack TT cable Cat5e
Ground screen screen White with brown strip 


White with green stripe 

IR data Ring Red Brown with white stripe or solid brown

+5V Tip White Green with white stripe or solid

Function 3.5mm jack Audio (same Cat5e cable)
Ground screen screen White with orange stripe


White with blue stripe

Right Ring red Orange with white stripe

Left Tip blue Blue with white stripe