# `ExDlt645`
[🔗](https://github.com/Ultraluv/ex_dlt645/blob/v0.1.0/lib/ex_dlt645.ex#L1)

A complete, idiomatic Elixir/OTP communication library for the DL/T 645-2007
(and 1997) electricity meter protocol.

## Architecture & Key Features

- **Pure Functional Codec (`ExDlt645.Codec`)**: Stateless packet encoding, decoding,
  +0x33 modulo 256 transformation, and checksum verification with binary pattern matching.
- **Data Identifier Catalog (`ExDlt645.DataId`)**: Complete coverage of DL/T 645-2007
  tables (A.1 Energy, A.2 Demand, A.3 Variables, A.4 Events, A.5 Parameters, A.6 Freeze, A.7 Load).
- **BCD Number & Datetime Engine (`ExDlt645.BCD`)**: Fast little-endian BCD conversions for
  numeric readings, meter addresses, timestamps, and wildcard matching.
- **Streaming Framer (`ExDlt645.Framer`)**: `Circuits.UART.Framing` behaviour implementation
  featuring preamble stripping, frame length deduction, and sliding-window byte-by-byte resynchronization.
- **Pluggable Transport Layer (`ExDlt645.Transport`)**:
  - Hardware UART (`ExDlt645.Transport.UART`) powered by `Circuits.UART`.
  - In-Memory Virtual Bus (`ExDlt645.Transport.Virtual` & `ExDlt645.VirtualBus`) for hardware-free CI/CD and simulation.
  - Raw TCP Client (`ExDlt645.Transport.Tcp`) for Ethernet/4G DTU serial servers.
- **Master Collector (`ExDlt645.Master`)**: Half-duplex serialized request execution,
  busy guard, active (asynchronous event streaming) and passive (synchronous call) modes.
- **Slave Meter Simulator (`ExDlt645.Slave`)**: In-memory virtual meter grid component for
  automated testing and interactive protocol playgrounds.
- **Telemetry (`ExDlt645.Telemetry`)**: Start/stop measurements with RTT for all requests.

## Quick Start

### 1. In-Memory Virtual Loopback Testing (Hardware-free)

```elixir
# Start a virtual electric meter slave
{:ok, _slave} = ExDlt645.Slave.start_link(address: "123456789012", tty: "virtual")

# Start a master collector on the same virtual bus
{:ok, master} = ExDlt645.Master.start_link(tty: "virtual")

# Read Total Forward Active Energy (DI: 0x00010000)
{:ok, energy} = ExDlt645.read_data(master, "123456789012", 0x00010000)
# => {:ok, 1234.56}

# Read Phase A Voltage (DI: 0x02010100)
{:ok, voltage} = ExDlt645.read_data(master, "123456789012", 0x02010100)
# => {:ok, 220.0}

# Broadcast read meter address
{:ok, addr} = ExDlt645.read_address(master)
# => {:ok, "123456789012"}
```

### 2. Physical RS-485 Serial Port

```elixir
{:ok, master} = ExDlt645.Master.start_link(
  tty: "/dev/ttyUSB0",
  uart_opts: [speed: 2400, parity: :even]
)

{:ok, energy} = ExDlt645.read_data(master, "001234567890", 0x00010000)
```

# `checksum`

# `custom_request`

# `decode_address`

# `decode_value`

# `encode_address`

# `encode_value`

# `freeze`

# `info`

# `inspect_frame`

# `lookup_di`

# `pack_read_request`

# `pack_read_response`

# `parse_frame`

# `read_address`

# `read_data`

# `search`

# `show_info`

# `sync_time`

# `write_address`

# `write_data`

---

*Consult [api-reference.md](api-reference.md) for complete listing*