I like the idea of using a GoPro (or other action camera) as a helmet cam when I'm riding my motorcycle, but I don't like having a big box glued to my forehead. I'm imagining a camera with the camera module and lens being attached by a cable to a box with the microprocessor, SD card, screen, etc. That way, I can put the small camera lens up front, and the put the rest of the camera somewhere more convenient.
Are there inherently any problems with having a longer bus/cable between the camera sensor itself and the rest of the electronics?
Best Answer
Timing
Some camera modules use a parallel data bus. In that case, if you don't keep all of the data lines exactly the same length (and to be completely accurate, exactly the same impedance and environment) the data sent and the data received might not be interpreted as the same value.
Drive Strength
The output drivers on the "camera" PCB are designed to meet spec only from the short hop into the sensor module itself (per the sensor module's datasheet). While the drivers are likely to be able to support a lot more capacitance, the longer cable (especially meter-scale) is probably the limit.
Interference (Signal Integrity)
Longer wires are more resonant at lower frequencies (e.g. to more frequencies overall). Therefore, the longer cable is more likely to pickup outside interfering signals.
Power Delivery
The sensor (camera module) circuitry requires power, which is delivered via the cable. The longer cable has, in general, higher impedance, which results in more voltage drooping and variation during operation. If the voltage droops to low, the camera module brown-out circuitry will activate (if equipped) or the module may latch-up (freeze) or otherwise malfunction.