51单片机密码锁Proteus仿真

Something About Return Value Of Master_readByte(addr) if you defined a unsigned char variable to save the values from Master_readByte(addr).it's value equal to ASCII,the value printf to screen used "%c" is ASCII codes! But,with using "%d" unexpected value will occour! if your defined a int variable to save the values from Master_readByte(addr). As we all know,a int needs 16 bits in Keil C51,the 8 bits of MSB are real value of Master_readByte(addr). And the 8 bits of LSB are all zeros.So,when using printf() with "%c" unexpected value will occour! Using printf() with "%d" ,the value printed is the real value multiply 256. Also we can use _iror_( ,8) function,then printf with "%c".The value printed is a char's(ACII) corresponding decimalism(DEC)value. Using printf() with "%d",print the real value.