本程序是基于447的，也在156上运行过，不过IO的初始化操作需要作些修改，其他可以完全不用修改。
程序开头的几行ADD A,@0xFF是非常有用的，在以后的文章中会有描述。
程序如下：
;SYSTEM CLOCK 4MHz
;IO port define
SDA == 4
SCL == 3
MSDA == 0
MSCL == 1
MCS == 2
MRST == 5
;Register define
TREG == 0X10
TCNT == 0X11
GCNT == 0X12
IICADDR == 0X1E
IICBUF == 0X28
IICDAT0 == 0X28
IICDAT1 == 0X29
IICDAT2 == 0X2A
IICDAT3 == 0X2B
IICDAT4 == 0X2C
IICDAT5 == 0X2D
IICDAT6 == 0X2E
IICDAT7 == 0X2F
INCLUDE "EM78P447S.H"
ORG 0X000
ADD A,@0XFF
ADD A,@0XFF
ADD A,@0XFF
ADD A,@0XFF
ADD A,@0XFF
START:
DISI
SET P6 P7 PULL UP EN
CONTR
MOV TREG,A
BC TREG,7
MOV A,TREG
CONTW
SET SCL SDA OUTPUT HIGH
MOV A,@0XFF
MOV TREG,A
BC TREG,SCL SCL OUTPUT
BC TREG,SDA SDA OUTPUT
MOV A,TREG
IOW IOC6
BS R6,SCL SCL HIGH
BS R6,SDA SDA HIGH
;********************************************************************
;读入的测试程序，读取2401的0x00～0x07地址内容
READ_2401:
MOV A,@0X00
MOV IICADDR,A
CALL IIC_R8BYT
RET
;********************************************************************
;写入的测试程序，向2401的0x00～0x07地址写入0x00
WRITE_2401:
MOV A,@0X00
MOV IICADDR,A
CLR IICDAT
CLR IICDAT
CLR IICDAT
CLR IICDAT
CLR IICDAT
CLR IICDAT
CLR IICDAT
CLR IICDAT
CALL IIC_W8BYT
RET
;********************************************************************
;与Microchip的2401接口程序
;********************************************************************
;IIC_W8BYT,向2401的指定地址写入8个字节数据
;地址由IICADDR指定，数据存在IICDAT0～IICDAT7
IIC_W8BYT:
CALL IIC_START
MOV A,@0XA0
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W8BYT
MOV A,IICADDR
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W8BYT
WRITE 8 BYTES TO 24C01
MOV A,@IICBUF
MOV R4,A
MOV A,@8
MOV GCNT,A
IIC_W8BYT1:
MOV A,R0
INC R4
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W8BYT
DJZ GCNT
JMP IIC_W8BYT1
CALL IIC_STOP
RET
;********************************************************************
;IIC_W1BYT,向2401的指定地址写入1个字节数据
;地址由IICADDR指定，数据存在IICDAT0
IIC_W1BYT:
CALL IIC_START
MOV A,@0XA0
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W1BYT
MOV A,IICADDR
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W1BYT
WRITE 1 BYTES TO 24C01
MOV A,@IICBUF
MOV A,IICDAT0
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_W1BYT1
CALL IIC_STOP
RET
;********************************************************************
;IIC_R8BYT，从2401的指定地址（IICADDR）读入8个字节数据
IIC_R8BYT:
CALL IIC_START
MOV A,@0XA0
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R8BYT
MOV A,IICADDR
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R8BYT
CALL IIC_START
MOV A,@0XA1
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R8BYT
READ 8 BYTES FROM 24C01
MOV A,@IICBUF
MOV R4,A
MOV A,@7
MOV GCNT,A
IIC_R8BYT1:
CALL IIC_RBYT
MOV R0,A
INC R4
CALL IIC_SACK
DJZ GCNT
JMP IIC_R8BYT1
CALL IIC_RBYT
MOV R0,A
CALL IIC_SNACK
CALL IIC_STOP
RET
;********************************************************************
;IIC_R1BYT,向2401的指定地址读出1个字节数据
;地址由IICADDR指定，数据存在IICDAT0
IIC_R1BYT:
CALL IIC_START
MOV A,@0XA0
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R1BYT
MOV A,IICADDR
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R1BYT
CALL IIC_START
MOV A,@0XA1
CALL IIC_WBYT
CALL IIC_CACK
JBC R3,GP IF GP=1 OPTION AGAIN
JMP IIC_R1BYT
READ 1 BYTES FROM 24C01
CALL IIC_RBYT
MOV IICDAT0,A
CALL IIC_SNACK
CALL IIC_STOP
RET
;********************************************************************
;IIC_START
IIC_START:
BS R6,SCL SCL=1
BS R6,SDA SDA=1
CALL IIC_DELAY
BC R6,SDA SDA=0
CALL IIC_DELAY
RET
;********************************************************************
;IIC_STOP
IIC_STOP:
BS R6,SCL SCL=1
BC R6,SDA SDA=0
CALL IIC_DELAY
BS R6,SDA SDA=1
CALL IIC_DELAY
RET
;********************************************************************
;IIC_CACK IF ACK,FIIC=0
IIC_CACK:
SET SDA INPUT
IOR IOC6
MOV TREG,A
BS TREG,SDA
MOV A,TREG
IOW IOC6
BS R6,SCL SCL=1
BC R3,GP
JBC R6,SDA
BS R3,GP
BC R6,SCL SCL=0
SET SDA OUTPUT
IOR IOC6
MOV TREG,A
BC TREG,SDA
MOV A,TREG
IOW IOC6
RET
;********************************************************************
;IIC_SACK
IIC_SACK:
BC R6,SDA SDA=0
NOP
BS R6,SCL SCL=1
CALL IIC_DELAY
BC R6,SCL SCL=0
CALL IIC_DELAY
RET
;********************************************************************
;IIC_SNACK
IIC_SNACK:
BS R6,SDA SDA=1
NOP
BS R6,SCL SCL=1
CALL IIC_DELAY
BC R6,SCL SCL=0
CALL IIC_DELAY
RET
;********************************************************************
;IIC_WBYT
IIC_WBYT:
MOV TREG,A
MOV A,@8
MOV TCNT,A
IIC_WBYT1:
BC R6,SCL SCL=0
JBC TREG,7
JMP IIC_WBIT1
JMP IIC_WBIT0
IIC_WBIT1:
BS R6,SDA
JMP IIC_WBYT2
IIC_WBIT0:
BC R6,SDA SDA=X
JMP IIC_WBYT2
IIC_WBYT2:
RLC TREG
CALL IIC_DELAY
BS R6,SCL SCL=1
CALL IIC_DELAY
DJZ TCNT
JMP IIC_WBYT1
BC R6,SCL SCL=0
CALL IIC_DELAY
RET
;********************************************************************
;IIC_RBYT
IIC_RBYT:
MOV A,@8
MOV TCNT,A
SET SDA INPUT
IOR IOC6
OR A,@0X10
IOW IOC6
IIC_RBYT1:
BS R6,SCL SCL=1
JBC R6,SDA
JMP IIC_RBIT1
JMP IIC_RBIT0
IIC_RBIT1:
BS TREG,0
JMP IIC_RBYT2
IIC_RBIT0:
BC TREG,0 SDA=X
JMP IIC_RBYT2
IIC_RBYT2:
RLC TREG
BC R6,SCL SCL=0
CALL IIC_DELAY
DJZ TCNT
JMP IIC_RBYT1
STORE READ RESULT
RRC TREG
MOV A,TREG
MOV TCNT,A
SET SDA OUTPUT
IOR IOC6
AND A,@0XEF
IOW IOC6
RESTORE READ RESULT
MOV A,TCNT
RET
;********************************************************************
;
IIC_DELAY:
NOP
NOP
RET
ORG 0XFFF
JMP START