How to Start a Rear-Camera Monitor Project

Start with the problem the screen solves

The logic behind a rear-camera monitor is simple. A phone's rear camera usually gives a better picture and a wider view than the front one, but when you shoot a selfie, a vlog or a livestream you cannot see the rear-camera frame. Add a screen, show that frame, and the user can shoot and watch at the same time.

Before writing any code, put the use case into one sentence: who uses the screen, and where.

• Selfies and vlogging: the screen travels with the phone, so size and weight come first.
• Desktop livestreaming: the screen sits on a desk and the user sits back, so a larger display is possible, and how the phone is mounted and how cables run matter more.
• Product shots and demos: the user needs to check framing and detail again and again.

Different scenarios lead to very different trade-offs in display size, mounting, and power and cable routing. Settle this first so you are not reworking it later.

Three technical facts to confirm first

The most common misunderstanding in these projects is assuming that any phone with a USB-C port can drive a screen. A phone having a USB-C port does not mean it supports USB-C DP video output. Video output has to be validated for each phone model, OS version and app.

At Idea to Device, three things are already in place:

1. USB-C DP video input is implemented.
2. Touch control, operating the phone from the touchscreen, is implemented.
3. Displays at 3.5, 4.0 and 10.1 inches have been brought up.

In other words, you can check your idea against working capability instead of proving feasibility from scratch.

From idea to something you can evaluate

There is no need to design a full system up front. The workable path is usually step by step:

1. Write a one-page brief: the use case, roughly what display size you need, how the phone is held, whether touch is required, and how cables run.
2. Choose a path. There are three common ones: wireless casting (Wi-Fi, or a paired transmitter and receiver), general wired display (DP/HDMI and similar), and Idea to Device custom rear-camera development using USB-C DP.
3. Validate the key assumptions on a working setup, above all whether your target phones output video and whether touch reaches the phone.
4. Agree the customizable items, then move into customization and prototyping.

What can be customized

• Display and panel integration
• PCBA dimensions and connector positions
• Image orientation and display layout
• Touch and interaction
• Power and cable layout
• Firmware

Three things to accept up front

Video output support and touch control must be validated per phone model, OS version and app.

• Scope, schedule, cost and quantity are assessed per project, and scope is agreed before work starts.
• Delivered materials, firmware and licensing scope are agreed per project.
• Contact us about demo and sample arrangements.

In short

Describe who the screen is for and where it is used, validate video output and touch on your target phones, and only then agree the scope of customization. Get that order right and the project will not stall halfway.