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ccslearner
Joined: 12 Jan 2013
Posts: 10
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| playing with key on PIC16F877A |
 Posted: Wed Apr 03, 2013 10:40 pm |
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hello everyone,
I am beginner in embedded system programming, still i have been learning it. The below code is when switch is pressed --> led ON.
My question is can I modify it to get when switch is pressed --> led OFF, such as reverse of this code, and initially all the led's are ON ?
| Code: |
#include <trial_1.h>
#define KEY_1 0x10
#define LED_1 0x01
#define KEY_2 0x20
#define LED_2 0x02
#define KEY_3 0x40
#define LED_3 0x04
#define SET_PIN 0x70
#define LED_OFF 0x0
#use delay(crystal=4000000)
void main ()
{
int8 key_input = LED_OFF;
port_b_pullups (true);
set_tris_b (SET_PIN) ; // 0111 0000 -> configure RB0, RB1, RB2 as output
// -> configure RB4, RB5, RB6 as input
output_b (LED_OFF) ; // Initialize all to off
//infinite loop
while (1)
{
key_input = SET_PIN & ~input_b();
if ( key_input==KEY_1) // 0x10 0001 0000 configure RB4 as input RB4
output_b (LED_1) ; // 0x01 0000 0001 configure Rb0 as output
else if( key_input==KEY_2 ) // 0x20 0010 0000 configure RB5 as input RB5
output_b (LED_2) ; //0x02 0000 0010 configure RB1 as output
else if( key_input==KEY_3) // 0x40 0100 0000 configure RB6 as input RB6
output_b (LED_3) ; //0x04 0000 0100 configure RB2 as output
}
}
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Thanks |
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ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
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| Posted: Thu Apr 04, 2013 6:52 am |
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Hi,
I'd recommend that you use the 'Input' function to test your switch, and the 'Output_toggle' function to control your LED. You should be able to accomplish what you want in 5 or 6 lines of code, and it will be much simpler and easy to read!
| Code: |
#define SW_Input PIN_A0
#define LED PIN_A1
main()
{
Output_high(LED);
while(1)
{
if (input(SW_Input))
output_toggle(LED);
}
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Obviously, change the pin defines to match your hardware, and change the 'Output_high' statement to 'Output_low' to reverse the startup behaviour of the LED. You'll also need to add the #include for your PIC, and the correct fuses.
John (the kinder and gentler version!) |
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