Posted on January 02, 2011 at 20:15Hi all,
Here's an improved code for the 4x3 keypad with debounce and autorepeat.
With STM8S 2MHz clock it performs pretty close to the PC keyboard.
The action() function is out from the keypad management state machine for clarity.
Suggestions and improvements are welcome.
Hope it helps.
Merry Xmas and happy holidays
Steven
u8 key = 255;
u8 oldkey = 255;
u8 AutoRptMax = 64;
u8 AutoRptCount = 0;
while(1)
{
key = GetKeyPressed(); //Scan the keypad to getting the code of the key pressed
// < Is it a valid key pressed ? >
if (key < 12) // YES
{
// < Is key still the old one ? >
if (key == oldkey) // YES
{
// (Start counting for autorepeat to occour)
DelayMS(50);
AutoRptCount++;
// < Is time to execute the key action? >
if (AutoRptCount >= AutoRptMax) // YES
{
Action(key); // perform the action according to the key code
AutoRptCount = 0; // reset the autorepeat counter to get ready for the next autorepeat event
AutoRptMax = 16; // make the autorepeat limit short for speeding up the next repetition when keeps keypressing
}
}
else // NO, the key is new brand
{
Action(key); // perform the action according to the key code
DelayMS(50); // and also make a little debouncing
}
} // END if (key < 12)
else // NO, the key is not among the 12 defined keys
{
// < Was the key pad released ? >
if (oldkey < 255 ) // YES
{
AutoRptCount = 0; // reset the autorepeat counter
AutoRptMax = 128; // and restart using the first typing delay long
}
}
oldkey = key;
}
void Action(u8 key)
{
switch(key)
{
case 9: // backspace (mode entry is ''right after writing'' so we need to cursor left twice)
LCD_DATA(0x10,0);
LCD_CHR(32);
LCD_DATA(0x10,0);
break;
case 11:
LCD_DATA(0x14,0); // cursor right
break;
default:
LCD_CHR(key + 48 + 1); // display keycode
break;
}
}
void DelayMS(int delay)
{
int nCount = 0;
while (delay != 0)
{
nCount = 100;
while (nCount != 0)
{
nCount--;
}
delay--;
}
}
