盛群半导体（Holtek）公司的HT98R068是双向无线电应用专用SOC MCU。在音讯处理功能方面, 包括预加重/去加重，压扩，可程序扰频设定，DTMF 编译码，可程序选择码编译码 及亚音频之CTCSS/DCS编解码。在MCU资源方面, 16kx16 ROM、1K Bytes RAM、34 I/O、内建有8个通道的12位ADC，4个通道的8位DAC，休眠快速唤醒、高低双频系统操作切换、串行传输接口SPI与RTC等功能，可减少外围零件、缩小PCB 尺寸及降低成本。主要是用于模拟无线电对讲机产品如 FRS, MURS, GMRS等市场。本文介绍了HT98R068主要特性和典型应用电路图。
The device is an ASSP MCU for analog two way radio applications such as FRS. This device contains an 8-bit MCU, Audio Processor, ADC, DAC as well as an Operational Amplifier for peripheral interfaces. Additionally there are external interrupt functions and 16K of OTP Program Memory and 1K of SRAM Data Memory for general MCU control application. The Internal Audio Processor supports various programmable functions. These functions include CTCSS/DCSS encoding/decoding, DTMF encoding/decoding, scramble/descramble, VOX, compandor and so on. By connecting to a suitable RF module, the device provides a cost effective and flexible audio RF solution. Applications should include products in the Leisure Radio application area such as General Mobile Radios, Personal Mobile Radios, Multiple User Radios etc.

HT98R068主要特性：
●●Operating voltage: 3V~5V
●●Up to 0.25μs instruction cycle with 16MHz system clock
●●OTP Program Memory:16K x 16
●●Data Memory: 1K x8
●●Up to 34 bidirectional I/O lines
●●Ocillator type: external 32768Hz crystal -- LXT
●●Internal PLL to generate the system clock
––Input reference clock : 32768Hz
––Output: 2.048MHz x4/x5/x6/x8 (optional)
●●Four operational modes: Normal, Slow, Idle, Sleep
●●Watchdog Timer function with WDT oscillator
●●Real Time Clock function
●●8 channel 12-bit A/D converter
●●4 channel 8-bit D/A converter
●●All instructions executed in one or two instruction cycles
●●Table read instructions
●●63 powerful instructions
●●Up to 10-level subroutine nesting
●●Bit manipulation instruction
●●Low voltage reset function
●●Low voltage detect function
●●SPI interface for external MCU control
●●Two 8-bit and signal 16-bit programmable Timer/Event Counter with overflow interrupt and prescaler
●●Programmable Frequency Divider -- PFD
●●PGA : 5bit Operational Amplifier Gain setup
●●Sub-tone processor
––CTCSS/DCS encode/decode
●●In-band-Tone processor
––DTMF encoder/decode
––Selective call encoder/decoder
––User defined tone encoder/decoder
●●Audio processor
––Pre-emphasis/De-emphasis
––Scrambler
––Compandor
––VOX
●●Package types: 48/64-pin LQFP

图1。HT98R068方框图

图2。HT98R068典型应用电路图