原创 串行通信接口典型应用举例

SCI_FLAG                   .usect         ".data0"，1                                     ;SCI标志寄存器<?xml:namespace prefix = o />

TXD_PTR                   .usect         ".data0"，8                                     ;发送的数据存放区

RXD_PTR                   .usect         ".data0"，8                                     ;接收到的数据存放区

                            .include           "F2407REGS.H"            ;引用头部文件

.def               _c_int0

;（1）建立中断向量表

                            .sect         ".vectors"                                        ;定义主向量段

RSVECT             B    _c_int0                                            ;PM 0        复位向量                         1

INT1                          B    GISR1                                               ;PM 2         中断优先级1                   4

INT2                          B    PHANTOM                                   ;PM 4        中断优先级2                  5

INT3                          B    PHANTOM                                   ;PM 6        中断优先级3                  6

INT4                          B    PHANTOM                                   ;PM 8        中断优先级4                  7

INT5                          B    PHANTOM                                   ;PM A        中断优先级5                  8

INT6                          B    PHANTOM                                   ;PM C        中断优先级6                  9

RESERVED      B    PHANTOM                                   ;PM E        (保留位)                      10

SW_INT8        B    PHANTOM                                   ;PM 10    用户定义软件中断            —

                                             …

SW_INT31       B    PHANTOM                                   ;PM 3E    用户定义软件中断         —

;中断子向量入口定义pvecs

                            .sect         ".pvecs"                                          ;定义子向量段

PVECTORS        B         PHANTOM                                     ;保留向量地址偏移量0000h

                            B         PHANTOM                                     ;保留向量地址偏移量0001h

                                             …

                            B         PHANTOM                                     ;保留向量地址偏移量0005h

                            B         SCI_RX_ISR                                     ;保留向量地址偏移量0006h SCI接收中断

                            B         PHANTOM                                     ;保留向量地址偏移量0007h

                                             …

                            B         PHANTOM                                     ;保留向量地址偏移量0041h

;（2）主程序：

        .text

_c_int0    

SETC          INTM

               CLRC          SXM

               CLRC          OVM

CLRC          CNF

LDP                   #0E0H

SPLK                  #81FEH，SCSR1                                     ;CLKIN=6 M，CLKOUT=24 M

SPLK                  #0E8h，WDCR                                   ;关看门狗

                   CALL         SCI_INIT                                       ;调串口初始化程序

                   LDP           #5H

                   SPLK                   #00H，SCI_FLAG                            ;清发送软件标志位

TXD_LOOP：  

                   LDP           #5H

                   BIT            SCI_FLAG，BIT0

                   BCND           TXD_DATA，TC                            ;SCI_FLAG.0=1则发送数据

                   B                WAIT

TXD_DATA：                                                                   ;发送N个数据程序

                   MAR                   *，AR0

                   LAR          AR0，#TXD_PTR

                   ADRK         #N+1                                                        ;发送N个数据

                   MAR                   *，AR4

                   LACC         *+                                                   ;读数据

                   CMPR         00

                   BCND         TXD_DATA_END，TC                 ;判数据发送完？

                   MAR                   *，AR2

                   SACL         *，AR4                                          ;数据送SCITXBUF寄存器

XMIT_RDY：  

                   LDP           #DP_PF1

                   BIT            SCICTL2，BIT7

                   BCND         XMIT_RDY，NTC                         ;判发送器是否空？

                   B                TXD_DATA

TXD_DATA_END：

                   MAR                   *， AR4

                   LAR          AR4，#TXD_PTR                           ;恢复发送的数据指针

                   LDP             #5H

                   SPLK                   #00H，SCI_FLAG                            ;清发送软件标志位

WAIT：    NOP

                   B                TXD_LOOP

（3）串行通信初始化程序：

SCI_INIT：

                   LDP                    #0E1H

                   LACL         MCRA

                   OR             #03H

                   SACL         MCRA                                           ;配置串行口引脚为特殊功能：TXD、RXD

                   LDP                   #DP_PF1  

                   SPLK          #000FH，SCICCR                     ;地址位唤醒模式，8位数据，

;1位停止位，无奇偶校验

SPLK          #0007H，SCICTL1                             ;接收、发送、内部时钟使能 ，SLEEP=1

               SPLK          #0002H，SCICTL2                    ;接收中断使能

               SPLK          #0001H，SCIHBAUD

               SPLK          #0038H，SCILBAUD                          ;波特率为9600

               SPLK          #0027H，SCICTL1                    ;串口初始化完成

               LAR          AR1，#SCIRXBUF                         ;接收缓冲寄存器地址

               LAR          AR2，#SCITXBUF                         ;发送缓冲寄存器地址

               LAR          AR3，#RXD_PTR                           ;接收的数据指针

LAR          AR4，#TXD_PTR                            ;发送的数据指针

LDP          #0

                   SPLK                  #0001h，IMR                                     ;允许INT1中断

                   SPLK                  #0FFFFh，IFR                               ;清所有中断标志

                   CLRC         INTM                                             ;开总中断

                   RET

（4）中断程序

GISR1：                                                                              ;优先级INT1中断人口

                   ;保护现场

                   LDP           #0E0H

                   LACC         PIVR，1                                         ;读取外设中断向量寄存器（PIVR），并左移一位

                   ADD                  #PVECTORS                                     ;加上外设中断人口地址

                   BACC                                                                 ;跳到相应的中断服务子程序

SCI_RX_ISR：                                                                   ;接收中断服务程序

                   LDP           #DP_PF1

                   MAR                   *，AR1        

                   BIT            SCICTL1，BIT2

                   BCND         RXD_DATA，NTC                         ;SLEEP=0，接收数据

                   LACC         *                                                      ;读入地址

                   SUB           #0AAH

                   BCND         TXD_FLAG，EQ                            ;接收到的地址为AAH，则发送数据

                   SUB           #0001H

                   BCND         SCI_RX_END，NEQ                      ;地址错误，退出中断

                   SPLK                  #0033H，SCICTL1                     ;地址为ABH，则清SLEEP=0

;表示准备接收数据

                   B                SCI_RX_END

TXD_FLAG：                                                                    ;置发送标志

                   LDP           #5H

SPLK                  #01H，SCI_FLAG

                   B                SCI_RX_END

RXD_DATA：                                                                   ;接收N个数据

                   LACC         *，AR3                                          ;读入数据

                   SACL         *+，AR0                                        ;保存数据

                   LAR          AR0，#RXD_PTR

                   ADRK         #N

                   MAR                   *，AR3

                   CMPR         00

                   BCND         SCI_RX_END，NTC                      ;判是否接收完

                   LAR          AR3，#RX_PTR                              ;恢复接收的数据指针

                   SPLK                  #0037H，SCICTL1                     ;置SLEEP=1表示准备接收地址

SCI_RX_END：                                                                           ;中断返回

                   ;恢复现场

                   CLRC         INTM                                             ;开总中断，因为一进中断就

;自动关闭总中断

                   RET

（5）假中断程序

PHANTOM      

KICK_DOG                                                         ;复位看门狗

                   RET

                   END