接口芯片综合应用课件.ppt

例1 8253与8251综合应用举例;流程图;参考程序;;******************************; ;*8251串行通讯(自发自收)*; ;******************************; data segment ioport equ 5400h-0280h ;tpc 卡中设备的io地址 io8253t0 equ ioport+280h io8253ctrl equ ioport+283h io8251a equ ioport+2b8h io8251b equ ioport+2b9h mes1 db you can play a key on the keybord!,0dh,0ah,24h mes2 dd mes1 data ends stacks segment stack db 100 dup (?) stacks ends code segment assume cs:code,ds:data,ss:stacks;start: mov ax,data mov ds,ax mov dx,io8253ctrl ;设置8253计数器0工作方式 mov al,16h ;00 01 011 0 out dx,al mov dx,io8253t0 mov al,52 ;给8253计数器0送初值 out dx,al mov dx,io8251b ;初始化8251 xor al,al mov cx,03 ;向8251控制端口送3个0 delay: call out1 loop delay mov al,40h ;向8251控制端口送40H,使其复位 call out1; mov al,4eh ;设置为1个停止位,8个数据位,波特率因子为16 call out1 mov al,27h ;向8251送控制字允许其发送和接收 call out1 lds dx,mes2 ;显示提示信息 mov ah,09 int 21h waiti: mov dx,io8251b in al,dx test al,01 ;发送是否准备好 jz waiti mov ah,01h ;是,从键盘上读一字符 int 21h cmp al,27 jz exit ;若为ESC键,则结束返回 inc al mov dx,io8251a out dx,al ;发送 mov cx,40h delay: loop delay ;延时;next: mov dx,io8251b in al,dx test al,02h ;检查接收是否准备好 jz next ;没有,等待 mov dx,io8251a in al,dx ;准备好，接收 mov dl,al mov ah,02h ;显示接收到的字符 int 21h jmp waiti exit: mov ax,4c00h ;退出 int 21h;例2 8253、8255A与8259A综合应用举例; 8253、8255A与8259A接口电路图 ;;应用程序; csreg dw ? ipreg dw ? ;旧中断向量保存空间 portout db 00h ;中断计数 msg1 db 0dh,0ah,TPC pci card Interrupt,0dh,0ah,$ msg2 db 0dh,0ah,Press K0 to exit!,0dh,0ah,$ data ends stacks segment stack db 100 dup (?) stacks ends code segment assume cs:code,ds:data,ss:stacks,es:data .386 start: cli ;关中断 mov ax,data mov ds,ax mov es,ax; ;设置 tpc 卡中9054芯片端口,使能9054中断 mov dx,ioport_cent+68h ；中断使能寄存器 in ax,dx or ax,0900h ；D8=1，允许产