4412linux编写串口驱动,Tiny4412之串口（Uart）驱动编写

今天药忘吃喽~ 2023-01-21 02:30 209阅读 0赞

一：tiny4412串口驱动编写

1、串口通信简介

串口通信指串口按位(bit)发送和接收字节，串口通信的概念非常简单，串口按位(bit)发送和接收字节。尽管比按字节(byte)的并行通信慢，但是串口可以在使用一根线发送数据的同时用另一根线 接收数据。它很简单并且能够实现远距离通信。比如IEEE488定义并行通行状态时，规定设备线总长不得超过20米，并且任意两个设备间的长度不得超过2 米；而对于串口而言，长度可达1200米。

串口通信所采用的通信协议为RS-232，RS-232通信方式允许简单连接三线：Tx、Rx和地线。但是对于数据传输，双方必须对数据定时采用使用相同的波特率。RS-232(ANSI/EIA-232标准)是IBM-PC及其兼容机上的串行连接标准。可用于许多用途，比如连接鼠标、打印机或者Modem，同时也 可以接工业仪器仪表。用于驱动和连线的改进，实际应用中RS-232的传输长度或者速度常常超过标准的值。RS-232只限于PC串口和设备间点对点的通信。

2、串口的通信基本模型如下图所示：

![20180110172625428775.png][]

TXD:发送数据

RXD:接收数据

GND:地线

串口驱动跟其他外设的驱动配置流程差不多，大概分为如下几步：

(1)查看电路图，配置相应的gpio功能引脚

(2)配置串口控制器的相应寄存器

(3)测试串口接收、发送

今天用的是第一个串口com0，下面是电路图：

![20180110172625431704.png][]

找到相应的gpio功能引脚

![20180110172625434634.png][]

下面是串口工作的整个模式图：

![20180110172625436587.png][]

下面是串口控制器相应的寄存器：

![20180110172625437563.png][]

今天我们实验用到的几个主要的寄存器是：

ULCON0：数据格式控制寄存器(配置数据位，停止位，校验位等)；

UCON0：串口控制开关

UTXH0：发送数据

URXH0：接收数据

UTRSTAT0:数据收发状态寄存器

UBRDIV0，UFRACVAL0：配置波特率的

下面是uart所需要的工作得时钟频率，以及比特率计算公式：

![20180110172625439516.png][]

![20180110172625441469.png][]

经过计算uart所采用的SCLK\_UART为100M

UBRDIV0=(100000000)/(115200 x16) - 1 = 53.3=53=0x35;

UFRACVAL0= 4;

下面具体测试代码：

1 \#ifndef \_\_REGS\_H2 \#define \_\_REGS\_H

4 \#define gpa0base 0x11400000

5 \#define GPA0CON (\*(volatile unsigned long \*)(gpa0base + 0x0000))

7 \#define uart0base 0x13800000

8 \#define ULCON0 (\*(volatile unsigned long \*)(uart0base + 0x0000))

9 \#define UCON0 (\*(volatile unsigned long \*)(uart0base + 0x0004))

10 \#define UFCON0 (\*(volatile unsigned long \*)(uart0base + 0x0008))

11 \#define UMCON0 (\*(volatile unsigned long \*)(uart0base + 0x000C))

12 \#define UTRSTAT0 (\*(volatile unsigned long \*)(uart0base + 0x0010))

13 \#define UERSTAT0 (\*(volatile unsigned long \*)(uart0base + 0x0014))

14 \#define UFSTAT0 (\*(volatile unsigned long \*)(uart0base + 0x0018))

15 \#define UMSTAT0 (\*(volatile unsigned long \*)(uart0base + 0x001C))

16 \#define UTXH0 (\*(volatile unsigned char \*)(uart0base + 0x0020))

17 \#define URXH0 (\*(volatile unsigned char \*)(uart0base + 0x0024))

18 \#define UBRDIV0 (\*(volatile unsigned long \*)(uart0base + 0x0028))

19 \#define UFRACVAL0 (\*(volatile unsigned long \*)(uart0base + 0x002C))

20 \#define UINTP0 (\*(volatile unsigned long \*)(uart0base + 0x0030))

21 \#define UINTSP0 (\*(volatile unsigned long \*)(uart0base + 0x0034))

22 \#define UINTM0 (\*(volatile unsigned long \*)(uart0base + 0x0038))

24 \#define uart3base 0x13830000

25 \#define ULCON3 (\*(volatile unsigned long \*)(uart3base + 0x0000))

26 \#define UCON3 (\*(volatile unsigned long \*)(uart3base + 0x0004))

27 \#define UFCON3 (\*(volatile unsigned long \*)(uart3base + 0x0008))

28 \#define UMCON3 (\*(volatile unsigned long \*)(uart3base + 0x000C))

29 \#define UTRSTAT3 (\*(volatile unsigned long \*)(uart3base + 0x0010))

30 \#define UERSTAT3 (\*(volatile unsigned long \*)(uart3base + 0x0014))

31 \#define UFSTAT3 (\*(volatile unsigned long \*)(uart3base + 0x0018))

32 \#define UMSTAT3 (\*(volatile unsigned long \*)(uart3base + 0x001C))

33 \#define UTXH3 (\*(volatile unsigned char \*)(uart3base + 0x0020))

34 \#define URXH3 (\*(volatile unsigned char \*)(uart3base + 0x0024))

35 \#define UBRDIV3 (\*(volatile unsigned long \*)(uart3base + 0x0028))

36 \#define UFRACVAL3 (\*(volatile unsigned long \*)(uart3base + 0x002C))

37 \#define UINTP3 (\*(volatile unsigned long \*)(uart3base + 0x0030))

38 \#define UINTSP3 (\*(volatile unsigned long \*)(uart3base + 0x0034))

39 \#define UINTM3 (\*(volatile unsigned long \*)(uart3base + 0x0038))

41 \#endif //\_\_REGS\_H

1 \#ifndef \_\_UART\_H2 \#define \_\_UART\_H

4 voiduart\_init();5 voidset\_gpio();6 voidshow\_serial();7 void myputc(unsigned charc);8 unsigned char mygetc(void);9 void myputs(unsigned char \*str);10 void mygets(unsigned char \*str);11

12 \#endif //\_\_UART\_H

1 \#include "regs.h"

2 \#include "uart.h"

4 intmain()5 \{6 set\_gpio();7 uart\_init();8 show\_serial();9 return 0;10 \}11

12 voidshow\_serial()13 \{14 /\*循环进行数据收发\*/

15 unsigned char cmd\[512\];16 while(1) \{17 myputs("");18 mygets(cmd);19 myputs(cmd);20 myputs("\\n");21 \}22

23 \}24

25 void myputc(unsigned charc)26 \{27 while(!(UTRSTAT0 & (1 << 1)));//等待buffer为空，再发送字符

28 UTXH0 =c;29 \}30 unsigned char mygetc(void)31 \{32 unsigned charch;33 while(!(UTRSTAT0 & 1));//等待buffer不为空

34 ch =URXH0;35

36 returnch;37 \}38

39 void myputs(unsigned char \*str)40 \{41 while(\*str) \{42 myputc(\*str);43 if(\*str == ‘\\n‘)44 myputc(‘\\r‘);45 str++;46 \}47 \}48

49 void mygets(unsigned char \*str)50 \{51 unsigned charch;52 while(1) \{53 ch = mygetc();//获取字符

54 myputc(ch);55 if(ch == ‘\\r‘) \{56 myputc(‘\\n‘);57 break;58 \}59 \*str =ch;60 str++;61 \}62 \*str = 0;63 \}64

65 voidset\_gpio()66 \{67 /\*0x2 = UART\_0\_RXD68 \*0x2 = UART\_0\_TXD\*/

69 GPA0CON &= ~0xff;70 GPA0CON |= 0x22;71 \}72

73 voiduart\_init()74 \{75 /\*step 1:数据格式控制\*/

76 ULCON0 = 3; /\*8bit data 1bit stop no parity\*/

77 /\*step 2: uart 开关\*/

78 UCON0 = 1 | (1 << 2);79 /\*step 3: set Baud-rate\*/

80 UBRDIV0 = 0x35;81 UFRACVAL0 = 0x4;82 /\*step 4: 数据收发缓存\*/

83 //UTXH084 //URXH0

85 /\*step 5：数据收发状态寄存器\*/

86 //UTRSTAT0

87 \}

原文：http://www.cnblogs.com/wenqiang/p/4984756.html

[20180110172625428775.png]: /images/20221021/1a19cb12604e429fb0bd592d02266f84.png
[20180110172625431704.png]: /images/20221021/aa365c226c1b4d3c85776111fe2c3cb2.png
[20180110172625434634.png]: /images/20221021/099cddce0665455e9d5f05f395f38c40.png
[20180110172625436587.png]: /images/20221021/14abd9bbc1454fc1b571950e9f5209eb.png
[20180110172625437563.png]: /images/20221021/ce4b25979dfe40fe9557037d2ed60237.png
[20180110172625439516.png]: /images/20221021/7df4b9d04b2a487fb2cafc38228dae17.png
[20180110172625441469.png]: /images/20221021/0108cf8906934ba7b2df4660ea70e040.png