IAP可以方便用户更新FLASH内容，不过用户必须遵循一定规则，以确保IAP正确执行，否则可能引起不确定的结果，甚至损坏器件。此外，下文对于正确执行IAP有很好建议。
(1)没有IAP操作时，用户必须清IAPEN (CHPCON.0)位。可以防止系统意外触发IAP。此外，IAP需要使用内部HIRC振荡器。如果选择外部时钟源，禁止IAP将停止内部HIRC，可以达到省电的目的。注：写IAPEN受TA保护。
(2)当LOCK位(CONFIG0.1) 被激活，IAP读、写或擦除仍然有效。
在进行IAP时，如果中断打开应该临时清除EA位
擦除或编程的页不能是当前代码执行的页。否则会出现不可预计程序动作，甚至破坏存储的数据
使用flash存储器作为数据存储
在一般应用中，有时需要一些数据在断电情况下不能丢失，以便用户读回或更新，作为系统控制的参数。N76E003支持IAP功能并且存储在flash中的字节都可以用MOVC指令读取，所以很适合作为非易失数据存储器。Flash写次数为100,000次，以下参考应用代码：
汇编例程如下:
;******************************************************************************
; This code illustrates how to use IAP to make APROM 201h as a byte of
; Data Flash when user code is executed in APROM.
;******************************************************************************
PAGE_ERASE_AP EQU 00100010b
BYTE_PROGRAM_AP EQU 00100001b
ORG 0000h
MOV TA,#0Aah ;CHPCON is TA protected
MOV TA,#55h
ORL CHPCON,#00000001b ;IAPEN = 1, enable IAP mode
MOV TA,#0Aah ;IAPUEN is TA protected
MOV TA,#55h
ORL IAPUEN,#00000001b ;APUEN = 1, enable APROM update
MOV IAPCN,#PAGE_ERASE_AP ;Erase page 200h~27Fh
MOV IAPAH,#02h
MOV IAPAL,#00h
MOV IAPFD,#0FFh
MOV TA,#0Aah ;IAPTRG is TA protected
MOV TA,#55h
ORL IAPTRG,#00000001b ;write ‘1’ to IAPGO to trigger IAP process
MOV IAPCN,#BYTE_PROGRAM_AP ;Program 201h with 55h
MOV IAPAH,#02h
MOV IAPAL,#01h
MOV IAPFD,#55h
MOV TA,#0Aah
MOV TA,#55h
ORL IAPTRG,#00000001b
MOV TA,#0Aah
MOV TA,#55h
ANL IAPUEN,#11111110b ;APUEN = 0, disable APROM update
MOV TA,#0Aah
MOV TA,#55h
ANL CHPCON,#11111110b ;IAPEN = 0, disable IAP mode
MOV DPTR,#201h
CLR A
MOVC A,@A+DPTR ;Read content of address 201h
MOV P0,A
SJMP $
//******************************************************************************
// This code illustrates how to use IAP to make APROM 201h as a byte of
// Data Flash when user code is executed in APROM.
//******************************************************************************
#define PAGE_ERASE_AP 0x22
#define BYTE_PROGRAM_AP 0x21
/*Data Flash, as part of APROM, is read by MOVC. Data Flash can be defined as
128-element array in “code” area from absolute address 0x0200 */
volatile unsigned char code Data_Flash[128] _at_ 0x0200;
Main (void)
{
TA = 0xAA; //CHPCON is TA protected
TA = 0x55;
CHPCON |= 0x01; //IAPEN = 1, enable IAP mode
TA = 0xAA; //IAPUEN is TA protected
TA = 0x55;
IAPUEN |= 0x01; //APUEN = 1, enable APROM update
IAPCN = PAGE_ERASE_AP; //Erase page 200h~27Fh
IAPAH = 0x02;
IAPAL = 0x00;
IAPFD = 0xFF;
TA = 0xAA; //IAPTRG is TA protected
TA = 0x55;
IAPTRG |= 0x01; //write ‘1’ to IAPGO to trigger IAP process
IAPCN = BYTE_PROGRAM_AP; // Program 201h with 55h
IAPAH = 0x02;
IAPAL = 0x01;
IAPFD = 0x55;
TA = 0xAA;
TA = 0x55;
IAPTRG |= 0x01; //write ‘1’ to IAPGO to trigger IAP process
TA = 0xAA; //IAPUEN is TA protected
TA = 0x55;
IAPUEN &= ~0x01; //APUEN = 0, disable APROM update
TA = 0xAA; //CHPCON is TA protected
TA = 0x55;
CHPCON &= ~0x01; //IAPEN = 0, disable IAP mode
P0 = Data_Flash[1]; //Read content of address 200h+1
while(1);
}
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