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Saves ~250µA during button presses by fixing a bug that caused the GPIO interrupt to repeatedly trigger as long as the button was down.

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This commit is contained in:
Travis Goodspeed 2018-10-09 18:05:35 -04:00
parent 43e1ebce78
commit 13cdb36323
1 changed files with 23 additions and 6 deletions
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29
firmware/keypad.c
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@ -36,7 +36,6 @@ void key_init(){
P2DIR|=BIT7; // Buzzer is on P2.7.
//Trigger interrupts for keypresses so we needn't scan.
//P2IE|=BIT2|BIT1|BIT0;
P2IE=BIT3|BIT4|BIT5|BIT6;
}
@ -48,10 +47,15 @@ int key_pressed(){
//! Bitfields indicate pressed rows.
int key_row(){
int row;
/* Already the default directions when this is called, but uncomment
if used elsewhere.
P1DIR|=0x80; //P1.7 out.
P1OUT|=0x80; //P1.7 high.
P2DIR|=0x07; //P2.0, 2.1, 2.2 out.
P2OUT|=0x07; //P2.0, 2.1, 2.2 high.
*/
//We'll return this result, but after cleaning up.
row=(P2IN>>3)&0x0F;
@ -66,9 +70,9 @@ int key_col(){
P1OUT&=~0x80; //Low
P2DIR&=~0x07; //P2.0, 2.1, 2.2 in
P2DIR|= 0x78; //P2.3, 2.4, 2.5, 2.6 out
P2OUT&=~0x07; //P2.0, 2.1, 2.2 low.
P2OUT|= 0x78; //P2.3, 2.4, 2.5, 2.6 high
P2DIR|= 0x78; //P2.3, 2.4, 2.5, 2.6 out
//We'll return this result, but after cleaning up.
col=((P2IN&0x7)<<1) | ((P1IN&0x80)>>7);
@ -107,7 +111,7 @@ unsigned int key_scan(){
scan=(key_row()<<4)|key_col();
setdirections();
if(scan&0xF0)
return scan;
else{
@ -156,10 +160,20 @@ void __attribute__ ((interrupt(PORT2_VECTOR))) PORT2_ISR(void){
static char lastchar=0x00;
char newchar;
//It's important that we clear the flags, and *then* scan, to catch
//keyups.
P2IFG=0;
//We used to clear P2IFG here, but it would cause the interrupt to
//be re-triggered until the button was released, wasting a lot of
//power now that the CPU clock is fast.
//P2IFG=0;
//We must also configure the edge triggering such that we get
//another interrupt on the *change* rather than just because a
//button is still held.
P2IES=P2IN&(BIT3|BIT4|BIT5|BIT6);
//Scan for the new character, which we will compare to the old to
//reduce duplicates.
newchar=key_chr(key_scan());
//Bail quickly when the key is the same.
if(lastchar!=newchar){
@ -171,7 +185,10 @@ void __attribute__ ((interrupt(PORT2_VECTOR))) PORT2_ISR(void){
//printf(".");
}
//Fix the pin directions before we return.
setdirections();
//Clear the interrupt flags.
P2IFG=0;
}