Holtek公司的HT82A824R是高性能USB喇叭OTP MCU,集成了USB 2.0全速兼容SIE及符合微软WHQL要求之高性能数字模拟转换器与功率放大器和嵌入式微控制器.器件采用Holtek(盛群)八位微控制器为其核心，可提供8Kx16之程序内存容量、864x8数据存储器以及512x8的只读数据存储器，并提供HALT指令。其操作电压为4.0V~5.5V，系统频率最高可达16MHz，同时可提供21条I/O,主要用在i-Phone/i-Pod/i-Pad Docking产品.本文介绍了HT82A824R主要特性,方框图和应用电路.

HT82A824R高性能USB喇叭微控制器
This HT82A824R is an 8-bit high performance RISC microcontroller designed for USB Speaker related product applications. The HT82A824R combines a 16-bit DAC, USB transceiver, SIE (Serial Interface Engine), audio class processing unit, FIFO, 8-bit MCU into a single chip. The Sigma-Delta DAC in the HT82A824R is operating at the 48kHz or 44.1kHz sampling rate. The HT82A824R has a digital programmable gain amplifier. The gain range is from -32dB to +6dB. The external stereo audio input can be the other source of power amplifier by software control.
The HT82A824R has a Human Interface Device function that allows a user to control the playback volume at the device side. The HT82A824R also can mute the analog output signal by the operation of HID buttons.

HT82A824R主要特性:
CPU Features
USB 2.0 Full Speed Compatible
USB spec V1.1 full speed operation and USB audio device class spec V1.0
Operating voltage at fSYS = 6M/12MHz: 4.0V~5.5V
48KHz/44.1KHz sampling rate for audio playback selected by software
Embedded class AB power amplifier for ear phone speaker driving (32Ω)×2
Embedded High Performance 16-bit stereo audio Sigma-Delta DAC
Pass Microsoft® DTM (WHQL) USB audio device
Audio playback digital volume control
6 endpoints supported including endpoint 0
Support 1 Control, 2 Interrupts, 1 Isochronous and 2 Bulk transfers
One hardware implemented Isochronous transfer
Total FIFO size are 528 bytes (8, 8, 384, 32, 32, 64 for EP0~EP2,EP4~EP6)
8192×16 Program Memory
352×8 MCU type data memory RAM (Bank 0, Bank 9)
128×8×4 Speaker Output Data or 12-bit ADC Converted Data RAM (Bank1, Bank2, Bank3, Bank4)
USB Audio and 12-bit ADC Stereo Data Capture DMA
128×8×4 MCU Type General Purpose Data RAM (Bank5, Bank6, Bank7, Bank8)
6-channel 12-bit A/D converter
2-channel PWM function shared with PB2~PB3
Dual Programmable Attenuator for 2-channel external stereo audio input
Universal Asynchronous Receiver Transmitter (UART) shared with PB0~PB1
SPI interface (master and slave mode) shared with PC4~PC7
Programmable frequency divider (PFD) function shared with PC0
Power-down function and wake-up reduce power consumption
Up to 21 bidirectional I/O lines
Dual 16-bit programmable Timer/Event Counters with overflow interrupts
Watchdog Timer
16-level subroutine nesting
Bit manipulation instruction
16-bit table read instruction
63 powerful instructions.
All instructions executed within one or two machine cycles
Low voltage reset function((3.0V±0.3V)
48-pin LQFP package

图1. HT82A824R方框图

图2. HT82A824R应用电路图