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pls i need help on interfacing 4x4 hex kepad to pic16f877

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babatundeawe

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pic 74hc922

hi guys, pls i need help on interfacing 4x4 hex kepad to pic 16f877. pls good schematic and source code with comments will be appreciated.
thanks.
 

Re: pls i need help on interfacing 4x4 hex kepad to pic16f87

You can use this circuit, enable the pullup at RB4 - RB7 and set to zero RB0 - RB3 (only one for each cilce) to read each colon an read RB4 - RB7 to know hwo is pressed (red zero).

Code:
void Main(void)
{
//Enable pull ups for Bort B (4 to 7)
//Set bits 0 to 3 from port B to output mode

....
}

//Rotine to read a key (0 to 15) return true if pressed and false if not.
bool ReadKey(char keynr)
{
//Reset all outpurts
bit_set(Port_B, 0xF0);

//Select de colum
bit_clear(Port_B, (keynr >> 2));

//Read the line
return !(bit_test(Port_B, (keynr & 0x03) + 4));
}
if you have Any question, ask....

If I helped you, click at helped me...



babatundeawe said:
hi guys, pls i need help on interfacing 4x4 hex kepad to pic 16f877. pls good schematic and source code with comments will be appreciated.
thanks.
Click to expand...
[/img]
 
If you want to avoid key debounce in your code use 74HC922 key encoder IC, which will nullify key debouncing problem


Bibin John
www.bibinjohn.tk
 

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