关于内部数据寄存器的问题

neesam

关于内部数据寄存器的问题 [复制链接]

在keilC51里，用了可以位寻址的存储器，可是工程芯片设成89C51时编译可以通过，就是不能实现功能（在电脑上通过串口仿真）。只有把芯片改成89C52才可以实现。
在平凡单片机书上也写了用到内部数据存储器时工程里需要把芯片设成52系列的。
不知道这是为什么？51也有位寻址的存储器啊。
在实际应用中，51的芯片也不能实现想要的功能么？也必须用52的芯片么？
正在选芯片，希望大家指导啊！
附：用到的程序
unsigned char bdata hb; //用于实现hex向bin的转换
sbit hb_0 = hb^0;
for(i=0;i<3;i++)
{
        hb=hex;
        for(j=0;j<8;j++)
        {
                if(hb_0) bin[j]=1;
                else bin[j]=0;
                hb=hb>>1;
        }
}

rabbit_007

这是你的仿真器的问题，跟内部RAM没关系。你这个程序有必要这么麻烦吗，我晕!

unsigned char  hb ;
for(i=0;i <3;i++)
{
hb=hex;
for(j=0;j <8;j++)
{
bin[j] = hb & 0x01;

hb >>= 1;
}
}

搞定

starliu

Trouble with the bdata Memory Type
Some users have reported difficulties in using the bdata memory type. Using
bdata is similar to using the sfr modifier. The most common error is
encountered when referencing a bdata variable defined in another module. For
example:
extern bdata char xyz_flag;
sbit xyz_bit1 = xyz_flag^1;
In order to generate the appropriate instructions, the compiler must have the
absolute value of the reference to be generated. In the above example, this
cannot be done, as this address of xyz_flag cannot be known until after the
linking phase has been completed. Follow the rules below to avoid this problem.
1. A bdata variable (defined and used in the same way as an sfr) must be
defined in global space; not within the scope of a procedure.
2. A bdata bit variable (defined and used in the same way as an sbit) must also
be defined in global space, and cannot be located within the scope of a
procedure.
3. The definition of the bdata variable and the creation of its sbit access
component name must be accomplished where the compiler has a “view” of
both the variable and the component.
For example, declare the bdata variable and the bit component in the same
source module:
bdata char xyz_flag;
sbit xyz_bit1 = xyz_flag^1;
Then, declare the bit component external:
extern bit xyz_bit1;
As with any other declared and named C variable that reserves space, simply
define your bdata variable and its component sbits in a module. Then, use the
extern bit specifier to reference it as the need arises.

hemp

多谢啊，你的程序更简单了。就是说是keil的问题，实际上51芯片也是可以完成任务的。
不过因为单片机要控制MAX7219，所以还是要用到位寻址。这个有办法改的更简洁些么？多谢啊
unsigned char bdata v; //v为MAX7219 用可位操作全局变量
sbit v_7=v^7;
void MAX_input()
{
        unsigned char i;
        for(i=0;i<8;i++)
        {
                MAX_clk=0;
                MAX_din=v_7;
                MAX_clk=1;
                v=v<<1;
        }
}
void MAX_load(unsigned int m)
{
        MAX_cs=0;
        v=m>>8;
        MAX_input();
        v=m;
        MAX_input();
        MAX_cs=1;
}

guochenfang

这个也可以这样啊
unsigned char v; //v为MAX7219 用可位操作全局变量

void MAX_input()
{
unsigned char i;
for(i=0;i <8;i++)
{
MAX_clk=0;
MAX_din= (bit)(v & 0x80);
MAX_clk=1;
v <<= 1;
}

simba_chen

2楼的意思是说只要再用extern声明，编译器就可以识别了是吗？

sgyao

用bit做强制类型转换时输出的不是最低位么？
我赶紧去实验一下。多谢多谢！