The **HT82M980A** is an 8-bit high-performance microcontroller designed by **Holtek Semiconductor**, specifically optimized for computer peripherals like USB mice and keyboards. It integrates a USB engine and an optical mouse sensor interface. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical and hardware characteristics of the HT82M980A: | Feature | Specification | | :--- | :--- | | **CPU Core** | 8-bit Holtek High-Performance Core | | **Operating Voltage** | 4.4V to 5.5V | | **Program Memory** | 2K x 14 Flash Memory | | **Data RAM** | 96 x 8 bits | | **USB Interface** | USB 2.0 Low Speed (1.5Mbps) | | **I/O Pins** | Up to 12 Programmable I/O lines | | **Package Type** | 20-pin SSOP / 16-pin NSOP | --- ### 2. Functional Blocks The HT82M980A is more than just a CPU; it contains specific hardware blocks to handle HID (Human Interface Device) tasks: * **USB Engine:** Handles the USB protocol layer, including SIE (Serial Interface Engine), FIFO buffers, and USB transceiver. It supports 2 endpoints (Endpoint 0 and Endpoint 1). * **Oscillator:** It typically uses an external 6MHz crystal or ceramic resonator, which is internally multiplied to reach the USB operational frequency. * **HALT Mode:** Supports low power consumption and "USB Suspend" mode to meet green energy standards for PC peripherals. * **Watchdog Timer (WDT):** Prevents the system from crashing by resetting the MCU if the code gets stuck in a loop. --- ### 3. Application Circuit Example A typical implementation involves connecting the IC to a USB cable and mouse buttons. ```mermaid graph LR USB_Cable -->|D+/D-| HT82M980A HT82M980A -->|I/O| Left_Click_Button HT82M980A -->|I/O| Right_Click_Button HT82M980A -->|I/O| Scroll_Wheel_Encoder HT82M980A -->|SPI/Bus| Optical_Sensor_ADNS ``` --- ### 4. Why it is used? Designers choose the HT82M980A for the following reasons: 1. **Cost Efficiency:** It combines USB communication and general-purpose logic into one cheap package. 2. **Ease of Development:** Holtek provides a standard library for HID devices, making it easy to program mouse movements and button clicks. 3. **Low Component Count:** Requires very few external components (mostly capacitors and a crystal) to function.