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Hi,
I wanted to create a game where a player has to repeat a random pattern of flashing lights with the keys on the MSP430. The random pattern is created with an ADC - 0 represents the red light on P1.0 blinking and 1 the green light on P4.7.
After playing it myself I noticed that sometimes when I press a button once it is registered as pressed twice.
For example: The pattern is red/red/red/green (0/0/0/1) then pressing the left button twice and the right button once is enough because the first push of the left button is registered as two pushes.
I reduced the code of the game to a smaller program in which it's only necessary to repeate the pattern of the example above:
#include <msp430.h>
int pattern[4];
unsigned int index = 0;
unsigned int button;
unsigned int buttonPressed = 0;
void Initialize_LED(void)
{
P4DIR = P4DIR | 0x80;
P4OUT &= ~0x80;
P1DIR = P1DIR | 0x01;
P1OUT &=~0x01;
pattern[0] = 0;
pattern[1] = 0;
pattern[2] = 0;
pattern[3] = 1;
}
void Initialize_Buttons(void){
P1REN |= 0x02;
P1OUT |= 0x02;
P2REN |= 0x02;
P2OUT |= 0x02;
P1IFG &= ~0x02;
P2IFG &= ~0x02;
P1IE |= 0x02;
P2IE |= 0x02;
// Timer: ----------------------------
TA1CTL = TASSEL_1+ID_0+MC_2+TACLR; //
TA1R = 40000; //
// ----------------
_BIS_SR(GIE);
}
void main(void)
{
WDTCTL = WDTPW + WDTHOLD;
Initialize_LED();
Initialize_Buttons();
int done = 0;
while(done == 0){
if(buttonPressed == 1){
if(pattern[index] != button){
P1OUT ^= 0x01;
done++; //wrong button --> green light on
} else {
index++;
buttonPressed = 0;
if (index == 4){
done++;
}
}
}
}
P1OUT ^= 0x01; // correct pattern --> both lights on
P4OUT ^= 0x80;
}
#pragma vector=PORT1_VECTOR // ----------- Interrupt Service Routine -----------
__interrupt void Port1_Interrupt (void) {
buttonPressed = 1;
if (P1IFG&0x02){
button = 1;
P1IE &= ~0x02;
TA1CTL |= TAIE;
TA1R = 50000;
}
}
#pragma vector=PORT2_VECTOR // ----------- Interrupt Service Routine -----------
__interrupt void Port2_Interrupt (void) {
buttonPressed = 1;
if (P2IFG&0x02){
button = 0;
P2IE &= ~0x02;
TA1CTL |= TAIE;
TA1R = 50000;
}
}
#pragma vector=TIMER1_A1_VECTOR // Timer1_A3 Interrupt Vector(TAIV) handler
__interrupt void TIMER1_A1_ISR(void)
{
switch (__even_in_range(TA1IV, 14))
{
case 0: break;
case 2: break;
case 4: break;
case 6: break;
case 8: break;
case 10: break;
case 12: break;
case 14:
P1IFG &= ~0x02;
P1IE |= 0x02;
P2IFG &= ~0x02;
P2IE |= 0x02;
TA1CTL &= ~TAIE;
break;
default: break;
}
}I went through the code with the debugger but can't find the reason why this keeps happening. Is someone able to help me?
Thanks for your time!
Hello Martin,
This phenomena is called switch bouncing (one push from human perspective, multiple pushes from MSP430 perspective) and requires a technique called switch debouncing. To get you started, check out the following resources. You can find several threads and other resources online by searching for "msp430 debounce".
Debouncing Switches on MSP430G2553 - MSP low-power microcontroller forum - MSP low-power microcontrollers...
Other Parts Discussed in Thread: MSP430G2553 I'm trying to handle 3 separate push buttons on P1.3, P1.4, and P1.5 on an msp430g2553. I'm using some sample code
DEBOUNCING THE SWITCH S2(P1.3) IN MSP430 - MSP low-power microcontroller forum - MSP low-power microcontrollers...
HAI
i am using p1.3 as a switch so that when i push it..it generates the interrupt and in the port ISR..i m sending a character by UART...i m getting the output
Regards,
James
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