Microcontroller Programming Experience

  1. For the single-chip microcomputer that can set the system clock, the delay program uniformly sets the system clock frequency to the lowest first, and then writes the delay
     function according to this lowest clock frequency. The advantages of this are: first, the delay under different system clocks is unified; second, power consumption is reduced.
  2. For the single-chip microcomputer system, different external clocks have different corresponding times for the delay program. For ease of use, add the pre-compilation instructions #ifdef/#else/#
     endif. In this way, if a system clock is pre-defined, the corresponding delay parameters are selected for compilation, and the main body of the delay program remains unchanged, but there is
     a delay parameter in it, and the corresponding parameters are selected according to the pre-definition.

2. For loop processing:
   Use for(i=XX,i>0,i--) instead of for(i=0;i    For two or more layers of for loops, frequent loops are placed in the inner layer to reduce the time spent on jumping between loops.

3. Operation of peripherals: You can operate the peripherals as a file. For example, you can treat the LCD as a file. To print strings
   or , you can use fprintf() (51's C standard library does not support it, but you can write a file operation library yourself). As long as it is an input and output
   device, try to operate it with file operations.

4. Use of standard library functions:
  1. Standard input and output library (stdio.h):
   When a character string mixed with variable numbers (for example, send the nihao character string, and then send the value of the variable i) is sent to the LCD display or to the serial port, the format output function printf("nihao%d",i) can be used to
   send port; but it is not easy to display on the LCD. Usually, a function of converting numbers to strings is written,
   and then the original string is sent first, and then the string after digital conversion is sent. This is too troublesome. You can use the sprintf() function in the standard input and output library to complete it. Its
   prototype is: sprintf(char *buffer, const char *format, …), *buffer is the buffer to which the string and variable are written. You can
   use an array or a pointer. The subsequent format is the same as the printf() function; the corresponding function is the sscanf() function, which reads a string from the buffer
   , converts it to the corresponding type, and then assigns it to the specified variable.
   For example:
    #include
    void PrintToLcd(unsigned char *str)
    {
        ...
    }
    void main()
    {
        unsigned char *p;
        unsigned char i = 50;
        sprintf(p,"nihao%d",i);
        PrintToLcd(p);
    }
  2. String library (string.h)
    string concatenation (addition) char *strcat(char *dest,const char *stc)
   connects src to the end of the dest string and returns a pointer to dest
    String comparison int strcmp(char *str1,char *str2)
   Return value: less than 0: str1str2
    String copy 1 char *strcpy(char *dest,const char *src)
   Result Copy the contents of src into dest, the contents of the two strings are the same, and return a pointer to dest
    String copy 2 char *strdup(const char *src)
   src: source string to be copied, return value: pointer to the copied string
    String reversal char *strrev(char *s);
   returns a pointer to the reversed string
  3. Type conversion (math.h; stdlib.h)
   String to double precision (similar to StrToDouble in C++Builder) double atof(char *str)
   String to integer (similar to StrToInt) int atoi(char *str)
   String to long integer long atol(char *str)
   Floating point number to string char *ecvt(double value,int ndigit,int*dec,int *sign)
                   char *fcvt(double value,int ndigit,int*dec,int *sign)
    Input parameters: value: floating point number to be converted, ndigit: length of the converted string
    Output parameters: dec: decimal point position, sign: sign
    Returns the converted string pointer
   Integer to string char *itoa(int value,char *string,int radix)
    Input parameters: value: number to be converted, radix: Converted binary
    output parameter: string: The converted string
    returns a pointer to string.
   Long integer to string conversion char *ltoa(long value,char *string,int radix)