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ELIXIR: Hardware Communication (UART) Ranked #22 globally, yet revered as a powerhouse. Strengths: Massive concurrency, fault tolerance, and incredibly fast binary pattern matching. Runs on the Erlang VM. 1. Dynamic Environment Setup Instead of requiring a full project structure, we can use Mix.install to reach out to the Hex package manager and download the circuits_uart library directly into memory. This makes the script completely portable and self-contained. 2. Spawning the Worker Process Because Elixir is highly concurrent, it doesn't just open a file stream; it spawns a dedicated, lightweight process (a GenServer) to manage the hardware communication. You are holding onto the "address" of this worker (PID) to issue commands to it later. 3. Hardware Discovery Query your operating system for any attached serial devices. It returns a map detailing the vendor IDs, product IDs, and port names (like COM3 on Windows or ttyUSB0 on Linux) so you can verify the computer actually sees your hardware. 4. Establishing the Connection We then tell our worker process (PID) to seize control of the specific port. • speed: 115200 (baud rate). Both sender and receiver must be configured to the exact same speed, or the data will look like gibberish. • active: false (passive mode). The script will only read data from the wire when you explicitly ask it to, rather than flooding your application with data. Note: Change "COM3" to your specific port. 5. Sending a Test Payload This pushes your data down the physical transmit (Tx) wire. The \r\n (carriage return and line feed) is often required by hardware devices to recognize that a command has finished sending. 6. Waiting for Response The script pauses and listens on the receive (Rx) wire. The 1000 is a timeout in milliseconds. If the hardware does not reply within one second, the script stops waiting so that the program does not hang forever. Finally, it prints whatever binary data came back.

# uart_demo.exs Mix.install([  {:circuits_uart, "~> 1.5"}]) alias Circuits.UART {:ok, pid} = UART.start_link() IO.inspect(UART.enumerate(), label: "Available Ports") UART.open(pid, "COM3", speed: 115200, active: false) UART.write(pid, "PING\r\n") {:ok, data} = UART.read(pid, 1000)IO.inspect(data, label: "Response")