The **HT86B40** is a specific 8-bit high-performance microcontroller (MCU) developed by Holtek Semiconductor, specifically designed for applications requiring voice and sound synthesis. It belongs to the "Voice/Music MCU" series. --- ### 1. General Specifications The HT86B40 integrates an 8-bit MCU core with a built-in Voice ROM and a Digital-to-Analog Converter (DAC). | Feature | Specification | | :--- | :--- | | **Operating Voltage** | 2.2V ~ 5.5V | | **CPU Core** | 8-bit Holtek RISC | | **Program Memory** | 4K x 15 bits | | **RAM (Data Memory)** | 160 x 8 bits | | **Voice ROM Size** | 128K x 10 bits | | **I/O Pins** | Up to 12 bidirectional pins | | **Audio Output** | 12-bit Current DAC | --- ### 2. Key Electronic Components & Features #### A. Voice Synthesis Engine The defining feature of the HT86B40 is its ability to play back recorded voice or synthesized music. * **Voice ROM:** Stores compressed audio data. * **Sampling Rate:** Supports various sampling rates for high-quality audio reproduction. #### B. Peripheral Subsystems * **Timers:** Includes an 8-bit programmable timer with overflow interrupts, used for precise timing or creating PWM signals. * **Oscillator Options:** Supports external Crystal, RC, or internal RC oscillators to balance cost and timing accuracy. * **LVR (Low Voltage Reset):** Automatically resets the device if the voltage drops below a functional threshold, preventing erratic behavior. #### C. Audio Output (Current DAC) Unlike many MCUs that require an external converter, the HT86B40 features a built-in **12-bit Current-type DAC**. * **Usage:** This pin directly drives a transistor or a simple power amplifier to push a speaker. * **External Components:** Usually requires a simple NPN transistor (like the 8050) and a few resistors/capacitors for basic audio amplification. --- ### 3. Pin Configuration Overview While the package (usually 16-pin NSOP) varies, the typical functional pins include: | Pin Type | Description | | :--- | :--- | | **VDD/VSS** | Power supply and Ground pins. | | **PA0 ~ PA7** | General-purpose I/O ports for buttons or LEDs. | | **PB0 ~ PB3** | Additional I/O or special function pins. | | **AUD** | The Audio output pin (Current DAC output). | | **OSC1/OSC2** | Input/Output for the system clock crystal or resistor. | --- ### 4. Typical Application Circuit To use the HT86B40 in a project, the electronic layout usually follows this pattern: 1. **Input:** Push-buttons connected to Port A pins (with internal pull-high resistors enabled). 2. **Processing:** The MCU reads the button press and fetches the corresponding voice data from the Voice ROM. 3. **Output:** The DAC converts the digital data to an analog signal. 4. **Amplification:** The signal passes through a capacitor to the base of a transistor to drive an 8-ohm speaker.