## Overview of the NET2282 The **NET2282** is a PCI to USB 2.0 High-Speed Peripheral Controller manufactured by PLX Technology (now part of Broadcom). It is designed to allow hardware designers to easily add a USB 2.0 interface to systems that already possess a local bus or PCI interface. --- ### 1. Key Technical Specifications The NET2282 functions as a bridge, translating data between a standard parallel bus and the USB serial protocol. | Feature | Specification | | :--- | :--- | | **USB Version** | USB 2.0 Hi-Speed (480 Mbps) | | **Interface** | 32-bit / 33MHz PCI Interface (or 16-bit Local Bus) | | **Endpoints** | Up to 6 configurable endpoints | | **FIFO Memory** | 8 KB of internal RAM for buffering | | **Power Supply** | 3.3V I/O with 1.8V Core (typically integrated regulator) | | **Package** | 120-pin TQFP | --- ### 2. Core Functional Blocks To understand the electronic operation, the chip is divided into several internal functional areas: * **USB Transceiver (PHY):** The physical layer that handles the high-speed differential signaling ($D+$ and $D-$). It includes the pull-up/pull-down resistors required for USB enumeration. * **Serial Interface Engine (SIE):** The logic that manages the USB protocol, including packet framing, CRC checking, and handshaking. * **DMA Controller:** A high-performance DMA engine that allows data to move between the USB endpoints and the PCI/Local bus without constant CPU intervention. * **Endpoint Buffers:** The 8 KB internal RAM is used to store incoming and outgoing data packets, ensuring the system can handle bursts of traffic. --- ### 3. Pinout and Connection Groups The 120 pins of the NET2282 are categorized into specific functional groups: #### A. Local Bus / PCI Interface These pins connect to the host processor or FPGA. * **AD[31:0]:** Address and Data multiplexed lines. * **CONTROL:** Signals like `CS#` (Chip Select), `RD#` (Read), and `WR#` (Write). * **IRQ:** Interrupt request line to signal the host when data is ready. #### B. USB Interface * **DP / DM:** The differential pair for USB communication. * **RPU:** Connection for an external precision resistor to calibrate the internal PHY. #### C. Power and Ground * **VDD33:** 3.3V Power for I/O buffers. * **VDD18:** 1.8V Power for the internal logic core. * **VSS:** Common ground. --- ### 4. Typical Application Circuit When integrating the NET2282 into a PCB design, the following electronic components are usually required: 1. **Crystal Oscillator:** A 30 MHz crystal is required to provide the clock reference for the USB PLL. 2. **Decoupling Capacitors:** 0.1µF and 10µF capacitors placed close to the VDD pins to filter high-frequency noise. 3. **Termination Resistors:** Specific resistors on the DP/DM lines (though many are integrated, external precision resistors are often used for calibration). --- ### 5. Programming Model From an electronic control perspective, the NET2282 appears to the host as a set of **Registers**. The developer writes to these registers to: * Set the USB Address. * Enable/Disable specific Endpoints. * Configure the DMA transfer size. * Monitor for "Bus Reset" or "Suspend" states.