Hi @andrea_seock
Please help me understand better what you are trying to achieve here.
Is this a set of coax adapters?
I might be able to interpret this as "J1 <-> J107" and then using a coax cable you go "J107 <-> J108", and then on another PCB you go "J108 <-> J2" Is that correct?
If so, then nicely done. You are close! We have not been perfect in describing the setup needed for Stereo, so I'll try my best to get you corrected:
- Stereo requires 2 unique I2C ports and 2 unique resets. Sometimes MCLK can be shared, but best to have 2.
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- You need to change "CCI_I2C_SDA1/SCL1" on J107 to match the names on J1 for "UPPER_CCI_I2C_SDA/SCL"
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- The CAM1_RST1_N on J2 needs to get over to J1 somehow (your net names are mismatched between J2 and J108). Then, CAM1_RST1_N needs to connect to J1 pin 32 (SPARE_MCLK/GPIO)
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- The MCLK signals are not corrected by name correctly. Please use LOWER_MCLK and UPPER_MCLK as on J1 to connect to J107
- We do not use the FLASH function. Pin 14 on J2 can be no connect, freeing up a signal.
I think you have a bunch more design DRCs for 1-pin nets and incorrect connections, but it is hard to see if you are doing this all on the same PCB schematic.
I encourage you to move the J1 to J107 on a separate design than the J2 to J108 so you can see all your DRCs and fix them.
Now, as for the coax cables, we are starting to introduce our own solutions. In fact, one of the solutions is for a synced tracking camera (also can be used for stereo). We are also about to release HIGH RES for two sensors as well.
Our Starling V2 platform will transition sensors over to coax and we will have all supporting hardware built in for it, so the individual parts will be available for sale as well. We are moving to AR0144 sensors instead of OV7251/9782 as part of this effort to stay NDAA compliant.
Making coax adapters is tricky and several customers have already have made bad hardware.
But, here are some tips for a successful coax adapter:
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Do not make the coax too long. For High Res applications, limit the total length to <150mm, for stereo/tracking cameras, you might be able to push 200mm max.
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The adapters must have impedance control for the differential pairs. Ground planes are a must. Do not try to route on 2-layers, use a 4-layer or more PCB.
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We ran some calculations based on specs from various coax cable vendors, and we found each conductor is pretty much limited to 150-200mA up to ~160mm in length or the DC drop will start to go below most sensor specs minimum voltages. So, any power load that needs 200mA+ needs a second conductor, so I am happy to see you have provided a second conductor for power
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DF56 does not support DC return through the coax shield. I cannot confirm for IPEX if they allow it or not. However, assuming it is the same, the only way to perform stereo is with two coax connectors, or increase from 26-pin to 30+ pins since you'll need 4 DC Ground returns.
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CSI lines must be length match, _P/_M to 0.25mm, and the entire group to <1.0mm. Spacing to other signals needs to be 3x the line width or more. Total CSI route length needs to be <200mm for 720p or the resolution and frame rates may need to drop.
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Plan on having short coax cables for testing. If your HW fails with your intended lengths, you can quickly try a shorter cable to see if the length is your issue.
Please let us know if this helped.
Thanks