Mikroelektronika MIKROE-742 데이터 시트

The Button library contains miscellaneous routines useful for a project development.

- Button 

484

- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 6

var Button_Pin :
sbit; sfr; external;

Declares button pins.

var Button_Pin : sbit
at PINB.B0; 

var
Button_Pin_Direction :
sbit; sfr; external;

Declares direction of the
button pin.

var
Button_Pin_Direction
: 

sbit at DDRB.B0;

function Button(time_ms : byte; active_state : byte) : byte;

- 

255

if the pin was in the active state for given period. 

- 

0

otherwise 

The function eliminates the influence of contact flickering upon pressing a but-
ton (debouncing). The Button pin is tested just after the function call and then
again after the debouncing period has expired. If the pin was in the active state
in both cases then the function returns 255 (true).

Parameters : 

- 

time_ms

: debouncing period in milliseconds 

- 

active_state

: determines what is considered as active state. Valid values: 0   

(logical zero) and 1 (logical one) 

Global variables : 

- 

Button_Pin

: Button pin line 

- 

Button_Pin_Direction

: Direction of the button pin 

must be defined before using this function.