## Technical Overview of BL-R2135B The **BL-R2135B** is a highly integrated IEEE 802.11b/g/n Wireless Local Area Network (WLAN) SDIO module. It is designed to provide high-speed wireless connectivity for embedded systems, IoT devices, and multimedia equipment. ### Core Specifications | Feature | Specification | | :--- | :--- | | **Main Chipset** | Realtek RTL8189FTV | | **Interface** | SDIO 1.1 / 2.0 / 3.0 | | **Wi-Fi Standard** | IEEE 802.11b/g/n (1T1R) | | **Frequency Range** | 2.412 GHz ~ 2.484 GHz | | **Data Rate** | Up to 150 Mbps (802.11n) | | **Operating Voltage** | 3.3V ± 0.2V | | **Antenna Type** | External (via half-hole / pad) | --- ### Key Electronic Components & Subsystems 1. **RTL8189FTV Controller**: The "brain" of the module. It integrates a MAC, a 1T1R capable baseband, and an RF radio. This single-chip solution reduces power consumption and the physical footprint. 2. **RF Front End**: * **Power Amplifier (PA)**: Boosts the signal for transmission. * **Low Noise Amplifier (LNA)**: Amplifies weak incoming signals with minimal noise addition. * **T/R Switch**: Switches the antenna between transmit and receive modes. 3. **Crystal Oscillator (24MHz/40MHz)**: Provides the precise clock frequency required for the radio frequency synthesis and the digital logic timing. 4. **Power Management Unit (PMU)**: Internal LDOs (Low Dropout Regulators) convert the 3.3V input to lower voltages (typically 1.2V) required by the core logic of the chipset. --- ### Pin Configuration Summary | Pin Number | Name | Type | Description | | :--- | :--- | :--- | :--- | | 1 | **SD_D2** | I/O | SDIO Data Line 2 | | 2 | **SD_D3** | I/O | SDIO Data Line 3 | | 3 | **SD_CMD** | I/O | SDIO Command Line | | 4 | **SD_CLK** | I | SDIO Clock | | 5 | **SD_D0** | I/O | SDIO Data Line 0 | | 6 | **SD_D1** | I/O | SDIO Data Line 1 | | 7 | **VBAT** | P | Main Power Supply (3.3V) | | 8 | **GND** | G | Ground | | 9 | **ANT** | I/O | RF Antenna Port | --- ### Application Usage The BL-R2135B is commonly found in: * **OTT Boxes** (Android TV boxes) * **IP Cameras** (Surveillance) * **Portable Devices** (PDAs, Tablets) * **Smart Home Appliances** ---