19.4.3 A20门..............................................................................................................539

19.4.4主机接口关闭功能（ LPCPD ） ........................................ ............... 542

19.4.5主机接口序列化中断操作（ SERIRQ ） ..................................... 546

19.4.6主机接口时钟开始请求（ CLKRUN ） ....................................... ........... 548

19.5中断源...............................................................................................................548

19.5.1 IBFI1 ， IBFI2 ， IBFI3和ERRI ....................................... ..................................... 548

19.5.2 SMI ， HIRQ1 ， HIRQ6 ， HIRQ9 ， HIRQ10 ， HIRQ11和HIRQ12 ........................ 549

19.6用法Notes.......................................................................................................................551

19.6.1设置模块停止模式........................................... ........................................ 551

在使用主机接口19.6.2说明.......................................... ................................... 551

第20 D / A转换器............................................ ..................................... 553

20.1特点.............................................................................................................................553

20.2输入/输出引脚..............................................................................................................554

20.3注册Descriptions.........................................................................................................554

20.3.1 D / A数据寄存器0和1 （ DADR0 ， DADR1 ） ................................. ................ 554

20.3.2 D / A控制寄存器（ DACR ） ....................................... ...................................... 555

20.4 Operation...........................................................................................................................556

20.5使用说明........................................................................................................................557

20.5.1设置模块停止模式........................................... ........................................ 557

第21节A / D转换............................................ ..................................... 559

21.1特点.............................................................................................................................559

21.2输入/输出引脚..............................................................................................................561

21.3注册Descriptions.........................................................................................................562

21.3.1 A / D数据寄存器A至D （ ADDRA到ADDRD ） ................................. ............ 562

21.3.2 A / D控制/状态寄存器（ ADCSR ） ..................................... ........................... 563

21.3.3 A / D控制寄存器（ ADCR ） ....................................... ...................................... 564

21.3.4键盘比较器控制寄存器（ KBCOMP ） ........................................ ..565

21.4 Operation...........................................................................................................................566

21.4.1单模.........................................................................................................566

21.4.2扫描Mode............................................................................................................566

21.4.3输入采样和A / D转换时间....................................... ................... 568

21.4.4外部触发输入时序........................................... .................................. 569

21.5中断源...............................................................................................................569

21.6 A / D转换精度的定义........................................... ................................... 570

21.7用法Notes.......................................................................................................................572

21.7.1允许的信号源阻抗........................................... ....................... 572

21.7.2影响的绝对精度........................................... .............................. 572

21.7.3设置模拟电源范围和其他引脚...................................... 573

在电路板设计21.7.4注意事项........................................... ............................................. 573

对噪声对策21.7.5注意事项........................................... .............................. 573

21.7.6设置模块停止模式........................................... ........................................ 574

修订版2.0 ， 08/02 ，三十八第十九页