benq-control

An unofficial library and daemon for remotely controlling benq-branded projectors via their serial protocol.

It provides:

• a simple tool for issuing commands to the projector;
• a web server to issue commands via a REST API; and
• a Rust library for controlling projectors from your own applications

Requirements

• A compatible projector with an rs232 serial port
• An rs232 adapter

Depending on your projector and adapter, you may also need a null model cable and/or a crossover cable. The projector's user manual will tell you if a crossover cable is needed (and if serial commands are supported in the first place).

This was developed for use with a BenQ TH685, but BenQ's serial protocol seems to be the same across most of their devices. The projector-tool's built-in utilities were designed with this projector in mind and so all options may not be compatible, however it can still execute arbitrary commands with projector-tool exec .... Refer to the user manual for a full list.

Building

To build all binaries, install the Rust toolchain (see https://rustup.rs) and run:

cargo build --bins --all-features --release

cross is recommended for cross-compiling. To build for most Raspberry Pi models, run:

RUSTFLAGS='-C link-args=-Wl,-rpath-link,/usr/lib/arm-linux-gnueabihf,-rpath-link,/lib/arm-linux-gnueabihf/' cross build --target-dir $(pwd)/target-cross --target=arm-unknown-linux-gnueabihf --all-features --bins --release

(note: only gnueabihf is supported when building via this method as it requires libavahi which is not available in the gnueabi (non-hf) build images)

(note: --target-dir is recommended to prevent spurious rebuilds when using both cargo build and cross build)

Home Assistant integration

A Home Assistant integration can be found in the ./benq_control directory allowing you to control most projector functions through Home Assistant and its connected apps, including Google Home, etc.

FAQs

I sent a command shortly after powering on the projector and commands stopped working. What gives?

Sending commands while the projector is changing power states occasionally crashes the projector's serial interface. You'll need to physically unplug the projector to fix this.

The library attempts to work around this by pausing command processing when power states are changed, but if the projector is powered on or off externally (e.g. via the power button) crashes can still occur.

Library users can submit Command::Sleep() commands to delay the processing thread if they notice the projector's power state has changed. Usually a single power query command (pow=?) is safe so long as you don't send further commands, however it may error ("Block item").