CORE8051-APB总线

1 APB总线

core8051s内核支持APB3总线，APB writebuffer 为{XWB3, XWB2, XWB1, ACC};

写访问

对FC00以上地址写值，即表示APB写操作，值为(XWB3, XWB2, XWB1, ACC)。

MOV DPTR, #0FC20H

MOVX @DPTR, A

读访问

MOV DPTR, #0FC20H

MOVX A, @DPTR即可更新 (XWB3, XWB2, XWB1, ACC)。

2 APB汇编示例

FC00-FFFFH空间映射了1个1K的SRAM，通过APB总线来读写。

apb3.asm

    XWB3 EQU   9CH
    XWB2 EQU   9BH
    XWB1 EQU   9AH

    XRB3 EQU   9FH
    XRB2 EQU   9EH
    XRB1 EQU   9DH

main:
     MOV R7, #0H
     MOV DPTR, #0ff40H
     MOV XWB3, #10H
     MOV XWB2, #10H
     MOV XWB1, #10H
     MOV ACC,  #10H

LOOP:
     MOVX @DPTR, A  ;apb write 

     MOVX A, @DPTR  ; apb read 

     ;display
     MOV SBUF, XRB3
     MOV SBUF, XRB2
     MOV SBUF, XRB1
     MOV SBUF, A

     INC DPTR
     INC R7
     INC XWB3
     INC XWB2
     INC XWB1
     MOV ACC, #10H
     ADD A, R7

     CJNE R7, #010H , LOOP 

     SJMP $
     

执行结果：

write op @f40: 10101010
read op @f40: 10101010
write op @f41: 11111111
read op @f41: 11111111
write op @f42: 12121212
read op @f42: 12121212
write op @f43: 13131313
read op @f43: 13131313
write op @f44: 14141414
read op @f44: 14141414
write op @f45: 15151515
read op @f45: 15151515
write op @f46: 16161616
read op @f46: 16161616
write op @f47: 17171717
read op @f47: 17171717
write op @f48: 18181818
read op @f48: 18181818
write op @f49: 19191919
read op @f49: 19191919
write op @f4a: 1a1a1a1a
read op @f4a: 1a1a1a1a
write op @f4b: 1b1b1b1b
read op @f4b: 1b1b1b1b
write op @f4c: 1c1c1c1c
read op @f4c: 1c1c1c1c
write op @f4d: 1d1d1d1d
read op @f4d: 1d1d1d1d
write op @f4e: 1e1e1e1e
read op @f4e: 1e1e1e1e
write op @f4f: 1f1f1f1f
read op @f4f: 1f1f1f1f