义隆单片机_总结

义隆单片机总结
1.EM78P173N使用外部中断时，需要外部上拉；
2.建议不用BC清除中断标志位；
3.判断某个I/O口的状态前，先执行MOV R,R
4.义隆C语言注意事项：
The total parameters passed to a function should be a fixed number.The compiler does not support uncertain parameter_list.
Recursive functions are not supported in the compiler.（不支持递归）
Do not use“struct”or“union”or“bit”as parameter for function.
Function pointer is not supported.
Bit data type cannot be used as a return value.
Bit data type is not supported in the IO control register.
Bit is a reserved word,so DO NOT use it as a name of“struct”or“union”.
Only global variable can be declared as“bit”data type.
You cannot assign location for Bit data in local field.Otherwise compilation error will occur.
For reduced RAM bank wastage,it is suggest that you use global variable in function,instead of using argument.
5.Bit data type cannot be used in“struct”and“union.”It is recommended to use
“bitfield”instead,such as:
union mybit{
unsigned int b0:1
unsigned int b1:1
unsigned int b2:1
unsigned int b3:1
unsigned int b4:1
unsigned int b5:1
unsigned int b6:1
unsigned int b7:1
};
6.bit变量推荐使用Struct定义：
struct
{
uint8_t b0:1;
uint8_t b1:1;
uint8_t b2:1;
uint8_t b3:1;
uint8_t b4:1;
uint8_t b5:1;
uint8_t b6:1;
uint8_t b7:1;
}
7.程序写法：
The Compiler allows you to access the C variable in the inline assembly as follows:
mov a,%<variable name>//move variable value to ACC
mov a,@%<variable name>//move address of variable to ACC
eg1:
int temp;
temp=0x03;//assume temp is at0x21of bank0
_asm{mov a,%temp}//move value0x03to ACC
_asm{mov a,@%temp}//move address0x21to ACC
6.
Eg:
asm
{
//Save procedure of rpage,iopage and bank register
mov a,0x3
mov%nbuf,a
mov a,0x04
mov%nbuf+1,a
bs0x03,7
bs0x03,6//Switch to other rpages
……
//Restore procedure of rpage,iopage and bank
mov a,%//register
mov0x03,a
mov a,%nbuf+1
mov0x04,a
}
7.
eg:
#define SetIO(portnum,var)_asm{mov a,@var}\
_asm{iow portnum}
#define SetReg(reg,3)_asm{mov a,@3}\
_asm{iow portnum}
8.Reserved Common Registers Operation
Compiler saves the common registers(0x11~0x1F)which the Compiler uses.Note the usage of“reti”instruction in restoring inline assembly in some MCUs
eg:
EM78567:This particular MCU has only one interrupt vector.The hardware does not save nor restore any register and Compiler just can save and restore R3and R4. void_intcall interrupt(void)@int
{
//Write your code(inline assembly or C)here
//restore ACC and R5
_asm{
reti//tell compiler to recover common registers here
SWAPA0X1E
MOV0X5,A
SWAP0X1F
SWAPA0X1F
}
}
void_intcall interrupt_l(void)@0x08:low_int0
{
//save ACC and R5
_asm{
MOV0X1F,A
SWAPA0X5
MOV0X1E,A
PAGE@0X0
}
}
8.ELAN C语言程序优化
(1)对位变量的取反操作，应该使用变量异或来实现，不能使用“~”，不推荐使用“！”，
Eg：对P67取反
推荐PORT6^=0X80;，不推荐P67=!P67;
(2)尽量不使用复杂运算，如果必须，尽量减少运算次数，可使用临时变量存储计算结果；
9.I2C调试总结：
（1）通信双方要共地，(如：仿真器与目标板要共地)；
（2）SDA读取状态时，应设置为输入；
10.。