Rear-view mirror on smart phone

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This post is about using a USB camera connected to a phone for the purpose of having a complementary rear-view mirror. The technology is, of course, more widely applicable. The reason for doing this is that the factory-supplied camera (Fiat Ducato 2021) is of mediocre quality and several “car cameras” on offer have proved to be problematic.

This post is ‘under construction’.

Ingredients

  • Phone (Android in this case):
    The phone should be of sufficient quality (OLED) and screen size to work well.
  • USB camera:
    Quality should be good, with a good controller and sensor.
  • Power supply:
    5V of sufficient quality, preferably tapped from LFP and otherwise the car battery.
  • USB cabling:
    Due to the distance, USB signals should be amplified with a special extension cable.
  • Software:
    ‘USB Camera Viewer’. This app has “mirror” functionality and is able to directly recognize the camera, making is hassle free. A paid version is obvious in case of permanent use.

Powering USB cameras

Direct power

Such a camera can be directly connected to a computer or a phone. This, of course, drains the phone battery quickly.

Power from Raspi

Another way, a bit out of the box:

USB video camera <---> Raspberry Pi <---> Monitor

This solves two challenges. The sum of the limited lengths of USB and HDMI cables is enough for large distances. It can be a dedicated solution for viewing only. It also creates possibilities to use sparse OLED displays in the range between 8″ and 12″. This is an example.

Power from LFP

USB-based cameras often need 5V. To turn 12V into 5V, a “step down converter” or, a “step-down
switching regulator” is required.

How can we work around that?

A popular voltage regulator is type MP1584 (datasheet). Another regulator is offered as a PCB under the names “Mini 560” and “Mini 560 Pro” . Here, the base is a JW5068A chip with slightly higher power (datasheet cached).

USB camera

USB camera “Lightburn” (IMX415+SPCA2688)

This is a USB camera with a Sony IMX415 sensor (Japan) and a SunplusIT SPCA2688 compressor (Taiwan). It is produced by Weinan Electronics with module size 38*38mm, named WN-L2104.K215L. There is a spec-sheet, cached here.

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