How to test serialport-rs for development.

Without hardware:

1. Compilation
2. cargo test

With a single unconnected device:

cargo run --example hardware_check <DEVICE>

And when wired in a physical loopback mode:

cargo run --example hardware_check <DEVICE> --loopback

With two devices connected to each other:

• cargo run --example hardware_check <DEVICE1> --loopback-port <DEVICE2>
• Also cargo run --example heartbeat <DEVICE1> <BAUD> in one terminal and cargo run --example receive_data <DEVICE2> <BAUD> in another

Can also verify trickier settings (like non-standard baud rates) using serial terminal programs like:

• screen (POSIX)
• CoolTerm (macOS)
• RealTerm (Windows)