Key program design can handle accelerator keys, one-key multi-function, etc.

My key program design can handle accelerator keys, one-key multi-function, etc. 
There is a P1 port determinant keyboard program example at the back.
 xwj  posted on  2005-4-15  16:36  Talking about single-chip microcomputers  ← Return to the forum    Report this post 

Hehe
Seeing the forum discussing keys, I also talked about my ideas for designing key programs. Welcome to criticize.

1. Generally, there is no delay in the keyboard program, but the keys are scanned by calling at intervals (such as 10 milliseconds) to release CPU resources as much as possible;
2. All keyboard programs are basically in one mode, which can handle accelerator keys, one-key multi-function, etc.;
3. There are only 2 external interfaces. To change to a keyboard with different hardware, you only need to add the keyboard program to the project and compile it. No other changes are required. It is very convenient.


Basically, it is a pattern:
Is there a key? - YES - the same as last time? - No - Keyold = 0; Exit 
  |       |
  |      YES - Keyold++;
  |       |
  |      Keyold == first key delay KEYDELAY? - No - Exit
  |       |
  |      YES - Keyok = 1;      // Press and hold for a certain period of time to send the first key, and then send the acceleration key
  |             Save the key value to Keydata; (decode if necessary)
  |             Keyold = KEYDELAY-KEYLOOP (delay for pressing and holding); - Exit
  |
  No - Keyold = 0? - YES - Exit
            |
           N0 - Keyok = 1;     // Not 0 means that the key was pressed and then released, of course, it is treated as a valid key and
                 saved to Keydata; (decode if necessary)
                 Keyold = 0; - Exit

All keyboard program external interfaces:
unsigned  char  KeyGetcode (void)         // Return key code
{
    key_ok = 0;
    return (key_data);
}

bit  KeyTest (void)             // Check if there is a key
{
    KeyScan ();             //Key scanreturn
    (key_ok);
}
     
 



//--------------------------------------------------------------------------//
//                                 Source program open to the public                               //
//                     (c)  Copyright  2001-2005  xuwenjun                      //
//                             All  Rights  Reserved                            //
//                                     V1.00                                  //
//--------------------------------------------------------------------------//
//Title:  P1 port determinant keyboard program                                                 //
//File name:  xwj_hlkey.c                                                        //
//Version:  V1.00                                                              //
//Modifier:  Xu WenjunE                          -mail:xuwenjun@21cn.com            //
//Date:  05-05-13                                                           //
//Description:  P1 port determinant keyboard program                                                 //
//Statement:                                                                    //
//         The following code is only provided free of charge for learning purposes, but the source must be stated in the file after quotation or modification.  //
//         Please contact the author for commercial use.     E-mail:xuwenjun@21cn.com            //
//         If you have any questions, please mailto  xuwenjun@21cn.com  and feel free   to communicate with me!                   //
//--------------------------------------------------------------------------//
//Old version:  No                              old version file name:                       //
//Created by:  Xu Wenjun                          E-mail: xuwenjun@21cn.com            //
//Date:  05-05-13                                                           //
//--------------------------------------------------------------------------//
#i nclude 
#i nclude  "xwj_hlkey.h"                 //   P1 port column keyboard   //
//#i nclude  "xwj_bp.h"                 //Peak buzzer

#define  KEYDELAY  25     
#define  KEYLOOP  10     
unsigned  char  key_bak;
unsigned  char  key_temp;
unsigned  char  key_old;
unsigned  char  key_data;
bit  key_ok;

    //   P1 port column keyboard   //
#define  KEYPIN_L   P1                //  Define the key scan column port as  the low four-bit input of P1   //
#define  KEYPIN_H   P1               //  Define the key scan row port as  the high four-bit scan output of P1   //

    //Internal private function   //
unsigned  char  fnKeycode(unsigned  char  key);      //   Output sequential key values ​​according to the keyboard mapping table             //

    //   P1 port column keyboard   //
//---------------------------------------------------------------------------//
void  KeyScan(void)                     //key scan
    {
    unsigned  char  sccode,recode;
    KEYPIN_L  =  KEYPIN_L|0x0f;                     //   P1 low four bits are column line input          //
    KEYPIN_H  =  KEYPIN_H&0x0f;                     //   P1 high four bits are row line all zero scan code  //
    if  ((KEYPIN_L&0x0f)  !=   0x0f)     //A key is pressed
        {
        key_temp  =  key value;              //Key scan, get key valueif
        (  key_temp  ==  key_bak)
            {
            key_old++;
            if  (key_old==KEYDELAY)                 //Continuous key, if not, shield this if
                {
                key_ok=1;
                key_data=fnKeycode(key_temp);     //Key decodingkey_old
                =KEYDELAY-KEYLOOP;
            }
        }
        else
            {
            key_old=0;
            key_bak=key_temp;
        }
    }
    else                             //Key lifted
        {
        if  (key_old)
            {
            key_ok=1;
            key_data=fnKeycode(key_temp);     //key decoding

        }
        key_old=0;
    }
    KEYPIN_H  =  KEYPIN_H|0xf0;
}

//---------------------------------------------------------------------------//

unsigned  char  KeyGetcode(void)         //return key code
{
    key_ok=0;
    return(key_data);
}

bit  KeyTest(void)                 //Check if there is a key
{
    KeyScan();             //Key scan
    return(key_ok);
}