第1 章 STC89 C52RC 开发平台和

工具·············································· 1

1.1 初识单片机··························2

1.1.1 单片机的概念·······················2

1.1.2 常见的51 单片机种类·············2

1.1.3 STC 单片机的命名规则···········3

1.2 STC89 C52RC 介绍················4

1.2.1 结构框架·····························4

1.2.2 引脚功能·····························5

1.2.3 *存储结构····························7

1.3 *51 核心板最小系统电路

介绍································· 10

1.3.1 电源电路··························· 10

1.3.2 时钟电路··························· 11

1.3.3 复位电路··························· 12

1.4 搭建开发环境····················· 13

1.4.1 本书资料包························ 13

1.4.2 Keil C51 的安装及设置·········· 13

1.4.3 STC-ISP 程序下载环境配置··· 18

思考题····································· 21

应用实践·································· 21

第2 章 C51 程序设计基础···················22

2.1 C51 程序的基本组成部分······ 23

2.1.1 包含头文件························ 23

2.1.2 主函数······························ 23

2.1.3 标识符与关键字·················· 24

2.1.4 程序注释··························· 24

2.1.5 其他规范····························24

2.2 C51 数据类型····················· 25

2.2.1 基本数据类型······················25

2.2.2 扩展数据类型······················26

2.3 C51 变量与常量·················· 26

2.3.1 变量··································27

2.3.2 常量··································29

2.4 C51 运算符························ 29

2.4.1 算术运算符·························29

2.4.2 关系运算符·························30

2.4.3 逻辑运算符·························30

2.4.4 位运算符····························31

2.5 C51 程序结构····················· 31

2.5.1 顺序结构····························32

2.5.2 选择结构····························32

2.5.3 循环结构····························35

2.6 C51 函数··························· 38

2.6.1 函数的定义·························38

2.6.2 函数的声明·························39

2.6.3 函数的参数·························39

2.6.4 函数的返回值······················39

2.6.5 函数的调用·························39

2.6.6 内部函数····························40

2.6.7 函数的命名规范···················41

2.7 C51 数组··························· 41

2.7.1 数组的定义·························41

2.7.2 数组的初始化······················41

2.7.3 数组元素的引用···················41

2.7.4 *二维数组·························· 42

2.7.5 字符串数组························ 42

2.7.6 数组的命名规范·················· 43

2.8 *C51 指针·························· 43

2.8.1 指针变量的定义和使用········· 44

2.8.2 指针变量的注意事项············ 45

2.8.3 指针与数组························ 45

2.9 Keil 编辑和编译及程序下载··· 46

2.9.1 新建Keil 工程····················· 46

2.9.2 新建并添加main.c 文件········· 48

2.9.3 配置工程··························· 49

2.9.4 编写程序代码····················· 49

2.9.5 程序编译··························· 50

2.9.6 STC-ISP 程序下载················ 51

思考题····································· 53

应用实践·································· 53

第3 章 LED 流水灯······························ 54

3.1 LED 灯的工作原理·············· 55

3.2 I/O 引脚部分寄存器············· 55

3.3 I/O 引脚控制的方法············· 56

3.3.1 字节操作··························· 56

3.3.2 位操作······························ 57

3.4 *I/O 引脚的内部结构············ 57

3.4.1 P0 组I/O 引脚····················· 57

3.4.2 P1 组I/O 引脚····················· 59

3.4.3 P2 组I/O 引脚····················· 60

3.4.4 P3 组I/O 引脚····················· 61

3.5 实例与代码解析·················· 62

3.5.1 位操作控制流水灯··············· 63

3.5.2 字节操作控制流水灯············ 66

思考题····································· 67

应用实践·································· 68

第4 章 独立按键输入·························· 69

4.1 按键检测原理····················· 70

4.2 按键软件去抖原理··············· 70

4.3 实例与代码解析·················· 72

思考题····································· 75

应用实践·································· 75

第5 章 蜂鸣器······································ 76

5.1 蜂鸣器介绍························ 77

5.2 蜂鸣器的工作原理··············· 77

5.3 实例与代码解析·················· 78

思考题····································· 80

应用实践·································· 80

第6 章 数码管显示······························ 82

6.1 数码管介绍························ 83

6.2 数码管的工作原理··············· 85

6.3 数码管静态显示·················· 86

6.4 数码管动态显示·················· 86

6.5 实例与代码解析·················· 87

思考题····································· 90

应用实践·································· 91

第7 章 外部中断·································· 92

7.1 中断的概念························ 93

7.2 中断系统框架····················· 94

7.2.1 中断源·······························94

7.2.2 中断触发条件······················95

7.2.3 中断请求标志······················97

7.2.4 中断允许控制······················98

7.2.5 中断优先级·························99

7.2.6 中断处理··························101

7.3 实例与代码解析·················103

思考题····································105

应用实践·································105

第8 章 定时器/计数器·······················107

8.1 机器周期与时钟周期···········108

8.2 定时器/计数器的工作原理····108

8.3 定时器/计数器系统框架·······110

8.3.1 定时/计数功能的选择········· 110

8.3.2 定时器/计数器的运行控制··· 111

8.3.3 工作模式与计数初值·········· 112

8.3.4 定时器/计数器中断············ 114

8.4 实例与代码解析·················117

8.4.1 计数器控制LED 灯············ 117

8.4.2 定时器控制LED 灯············ 120

思考题····································123

应用实践·································123

第9 章 PWM 与呼吸灯·····················124

9.1 PWM 基本参数··················125

9.1.1 电平标准························· 125

9.1.2 周期和频率······················ 125

9.1.3 占空比···························· 125

9.2 PWM 控制LED 亮度的

原理································126

9.3 PWM 输出原理··················126

9.3.1 输出PWM 信号················ 126

9.3.2 按照规律调节PWM 占空比···· 127

9.4 实例与代码解析·················129

思考题····································133

应用实践·································133

第10 章 串口通信······························134

10.1 通信协议介绍··················135

10.1.1 并行通信和串行通信······ 135

10.1.2 单工、半双工和全双工

数据传输····················· 136

10.2 串口通信协议介绍············136

10.2.1 UART 物理层··············· 137

10.2.2 UART 数据帧格式········· 137

10.2.3 UART 传输速率············ 138

10.2.4 UART 通信实例············ 138

10.3 UART 电路原理图·············139

10.4 串口中断························140

10.4.1 串口中断请求标志位·······140

10.4.2 串口中断允许控制位·······141

10.4.3 *串口中断优先级

控制位·························141

10.5 串口工作模式··················142

10.5.1 *工作模式0 ··················143

10.5.2 工作模式1····················143

10.5.3 *工作模式2 ··················147

10.5.4 *工作模式3 ··················149

10.6 实例与代码解析···············149

思考题····································155

应用实践·································155

第11 章 看门狗··································157

11.1 复位方法························158

11.1.1 外部RST 引脚复位·········158

11.1.2 软件复位······················158

11.1.3 通电/关电复位···············159

11.1.4 看门狗复位···················159

11.2 看门狗相关寄存器············159

11.3 看门狗溢出时间···············160

11.4 看门狗喂狗操作···············161

11.5 实例与代码解析···············161

思考题····································164

应用实践·································165

第12 章 内部Flash 读写··················166

12.1 ISP 与IAP·······················167

12.2 内部Flash 存储结构··········167

12.3 IAP 读写与擦除Flash 的

方法······························168

12.3.1 读取操作······················169

12.3.2 擦除操作······················170

12.3.3 写入操作······················171

12.4 Flash 读写注意事项···········172

12.5 实例与代码解析···············173

思考题····································181

应用实践·································181

附录·························································182

附录A 数制及转换方法············183

附录B 逻辑门表示符号············185

附录C 常用寄存器及部分位的

解释说明·····················186

附录D 51 核心板电路图···········191

参考文献·················································192