Akwụkwọ Ntuziaka Njikọta RFID Reader

// Request serial port access
const port = await navigator.serial.requestPort();
await port.open({
  baudRate: 115200,
  dataBits: 8,
  stopBits: 1,
  parity: "none",
  flowControl: "none",
  bufferSize: 4096,
});

// Get reader/writer streams
const reader = port.readable.getReader();
const writer = port.writable.getWriter();

import serial

port = serial.Serial(
    port="/dev/ttyUSB0",      # Linux/macOS
    # port="COM3",            # Windows
    baudrate=115200,
    bytesize=serial.EIGHTBITS,
    stopbits=serial.STOPBITS_ONE,
    parity=serial.PARITY_NONE,
    timeout=2.0,
)

# Flush buffers before communication
port.reset_input_buffer()
port.reset_output_buffer()

TX -> 5A 00 01 01 00 00 00 DC E5
       +----+ +------+ +----+ +----+ +------+ +------+
       | 5A | | 0001 | | 01 | | 00 | | 0000 | | DCE5 |
       +----+ +------+ +----+ +----+ +------+ +------+
        HDR     PCW    CAT   MID    LEN     CRC16

TX -> 5A 00 01 02 10 00 00 04 5A
       HDR  PCW   CAT MID LEN   CRC16

Response notifications (PID 0x1231) contain:
  - Antenna ID (1 byte)
  - RSSI value (1 byte, raw ADC 0-255)
  - EPC data (12+ bytes)
  - Frequency channel index (1 byte)

TX -> 5A 00 01 02 FF 00 00 88 5A
       HDR  PCW   CAT MID LEN   CRC16

TX -> 5A 00 01 02 03 00 04 0F 00 00 00 E1 EF
                              +-----------+
       Payload:               |0F 00 00 00| <- bitmask
                              +-----------+
       Bit 0 = ANT1, Bit 1 = ANT2, Bit 2 = ANT3, Bit 3 = ANT4
       0x0F = 0b00001111 -> all 4 ports enabled

EPC Hex: 3034257BF7194E4000001A85

Decoded:
  Header:         0x30 (SGTIN-96)
  Filter:         1 (Point-of-Sale)
  Partition:      5
  Company Prefix: 0614141
  Item Reference: 812345
  Serial:         6789
  GTIN-14:        80614141123458
  Digital Link:   https://id.gs1.org/01/80614141123458/21/6789

// NRN protocol WRITE_EPC_TAG command
TX -> 5A 00 01 02 11 00 0C [EPC_DATA_12_BYTES] [CRC16]

// The reader will:
// 1. Select the tag in its field
// 2. Write the provided EPC data to Bank 01
// 3. Return success/failure notification

// Access password required if tag is locked:
TX -> 5A 00 01 02 11 00 10 [ACCESS_PWD_4B] [EPC_DATA_12B] [CRC16]

TX -> 5A 00 01 02 01 00 04 1E 1E 1E 1E 67 FE
                              +-----------+
       Payload:               |1E 1E 1E 1E|
                              +-----------+
       0x1E = 30 decimal = 30 dBm per port

Power guidelines:
  - 33 dBm - Maximum range (~10m), dock doors
  - 30 dBm - Standard range (~6-8m), general use
  - 25 dBm - Medium range (~3-5m), conveyor belts
  - 20 dBm - Short range (~1-2m), point-of-sale
  - 15 dBm - Near-field (~0.5m), shelf readers

TX -> 5A 00 01 02 05 00 06 00 02 04 06 08 0A C4 1B

Channel mapping (formula: 920.0 + index x 0.5 MHz):
  Ch 0  -> 920.0 MHz
  Ch 2  -> 921.0 MHz
  Ch 4  -> 922.0 MHz
  Ch 6  -> 923.0 MHz
  Ch 8  -> 924.0 MHz
  Ch 10 -> 925.0 MHz

// 1. Enable antennas 1-4
await sendFrame("CONFIGURE_ANTENNA_ENABLE", [0x0F, 0x00, 0x00, 0x00]);

// 2. Set power to 30 dBm on all ports
await sendFrame("CONFIGURE_READER_POWER", [0x1E, 0x1E, 0x1E, 0x1E]);

// 3. Set working frequencies
await sendFrame("SET_WORKING_FREQUENCY", [0, 2, 4, 6, 8, 10]);

// 4. Set duplicate filter to 1000ms
await sendFrame("SET_FILTER_SETTINGS", [0x03, 0xE8]);

// 5. Start inventory
await sendFrame("READ_EPC_TAG");

// 6. Process tags...
reader.on("tag", (tag) => {
  const rssiDbm = -100 + Math.round((tag.rssi * 70) / 255);
  console.log(`EPC: ${tag.epc}, Ant: ${tag.antenna}, RSSI: ${rssiDbm} dBm`);
});

// 7. Stop when done
await sendFrame("STOP_INVENTORY");