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*第37759篇: 求助：8052总是写不进去at28c256
楼 主:
求助：8052总是写不进去at28c256板子上用8052给EEPROM at28c256写数据，总是写不进去，读出来全是0xff
下面是我编的两个c函数，分别用来读写，请高手百忙之中指点一下，谢谢！
unsigned char read_EE(unsigned int addr)
{
unsigned char output;
nWE_EE=1;
nCE_EE=1;
nOE_EE=1;
P0=(unsigned char)(0x00ff & addr);
P2=(unsigned char)((0xff00 & addr)> > 8);
nCE_EE=0;
nOE_EE=0;
output=P0;
nOE_EE=1;
nCE_EE=1;
return output;
}
// --------------------------------------------------------------------
// --------------------------------------------------------------------
void write_EE(unsigned int addr,unsigned char input)
{
nOE_EE=1;
nCE_EE=1;
nWE_EE=1;
P0=(unsigned char)(0x00ff & addr);
P2=(unsigned char)((0xff00 & addr)> > 8);
nCE_EE=0;
nWE_EE=0;
P0=input;
nWE_EE=1;
nCE_EE=1;
nOE_EE=1;
}
28cxx 有写保护/写允许命令的28cxx 有写保护/写允许命令的.
而且,写入是需要时间的.
写入后要经过大约20毫秒才能读出来