Mipi / CSI2 interfacing - how long can the cable be?

Jan 25, 2011 2 Replies

I need to place a Cmos sensor (720p HD content @ 25 fps or better) away from the processor interface. I might use the OV538 sensor.



I have no hands-on experience with mipi, I gather it is a LVDS like serialized signal. Connections are usually made over short flexifoils.



Question: when using e.g. cat5 grade twisted pair(s), how long can I expect a cable to be before signals are degraded and / or RFI problems arise?



Input welcome - thanks!


This is a completely wild-assed guess, but based on some camera I used to use that used LVDS, you were often pushing your luck beyond about 5-10' ("desktop" distances).

But it depends an awful lot on the data rates involved, terminations, etc. For a sensor meant to be connected via a few inches of cable, it's a likely safe bet the manufacturer hasn't necessarily characterized the maximum usable cable length, but it's also probably a safe bet you can get "some feet" out of it without much effort.

Am 25.01.2011 17:06, schrieb Blarp:

Typicalwise, the camera interface consists of a parallel bus (8lines and more), a horizontal and vertical sync line and a pixel clock. Additional there are I2C lines to configure the camera SoC - and normally there is some master clock provided from the mainboard. Masterclock - est. 13Mhz Pixelclock + Datalines >50MHz !!! (asymmetric) with 720p/25fps

I would say 2 inch using some wiring - and 20 inch using matched impedance flatfoil connection. Due to the fact that there are no differential signals - using twisted pair makes no sense. For everything else(longer) they invented HDMI;-)))

rgds.

Wolfgang

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