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i need to carry the signals from a Raspberry compute module to a camera module and vice versa. Since I need to place the camera around 4 foot away from the microComputer, and i want the connection to be sturdy, and I need to be able to connect and deconnect the camera hundreds of time, the flat ribbon cable that is "native" to Raspberry is not viable.

The signals/power that need to travel are:

  • three differential pairs (For data and clock)
  • 3V3 and GND
  • 4 logic signals

All logic signals and differential pairs are bidirectional. Power goes from the compute module to the camera module, which is totally passive.

I've experimented with an HDMI cable, printing custom PCB connector adapters on both ends and it works perfectly even for longer distances (3m or so). It has been working for months, so the idea is working. They even sell commercial adapters for this. I've also experimented with HDMI <-> miniHDMI and it works also, but the connectors are too bulky and moreover I've not found a cable with both endings miniHDMI.

Now I am looking for a similar, commercially available cable, with small connectors and able to carry the data I need.

I've tried with a miniDP but, because of my ignorance, I've overlooked the problem of power on pin20, so I have to discard it.

Now I've thought about USB-C, but it seems too complicated, with much logic in the connectors, I don't know if they are suitable. And moreover it seems that there are 3 differential pairs, but not enough signals for my use (I could work with just 3 control signals instead of 4, or at the very worst I think I could make do even with 2)

It puzzles me the thing that pins are replicated top and bottom (so inserting either way is unimportant)..

Any idea?

Thanks Z

P.S. At the moment I've experimented with using one of the "signal" channels to route 3V3. I've jury rigged the PCB at the end of the cable to pass the power to the 3V3 tracks. It seems to work. I just hope internally the signal strand is able to carry the power (even if amperage is quite low)

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  • \$\begingroup\$ two ethernet cables \$\endgroup\$
    – Neil_UK
    Sep 11, 2020 at 15:05
  • \$\begingroup\$ I guess a Lapp kabel and similar manufacturers make cables with several twisted pairs, also flex for servo motor feedback connecting cable with PUR isolation if you need also resistant to oil. Then choose a connector from Amphenol, Harting,... \$\endgroup\$ Sep 11, 2020 at 15:12
  • \$\begingroup\$ HDMI cable has enough conductors \$\endgroup\$ Sep 12, 2020 at 10:26
  • \$\begingroup\$ Hi @Jasen i know HDMI cables work. I've used them for months, but the connectors (either plug and receptacle) are too bulky. Mini HDMI could suit my needs, but I haven't found a cable with miniHDMI plug at both ends. \$\endgroup\$
    – zontar
    Sep 13, 2020 at 9:16
  • \$\begingroup\$ @MarkoBuršič that's a solution, thanks for the link. But I'd like to find a commercial cable that costs under 10$/€..at the moment the best solution (miniDP with power routed through a "signal" pin) is for a price of around 5 or 6 €. \$\endgroup\$
    – zontar
    Sep 13, 2020 at 9:18

1 Answer 1

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I can confirm that a miniDP cable is capable of what I intended to do. The only thing is, power should not be carried by pin 20, since in most (if not every) commercially available cables, it's an unconnected pin. So you have to choose another PIN to carry Power.

At the moment I am using pin 2 and 19 (for redundancy) The setup works

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