From 43257b8acee3414abe766a7b1225f1a24cfeea0b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Sat, 26 Jul 2014 20:30:39 -0700
Subject: [PATCH] use interrupts for switches

---
 pic/MDR/MDR.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/pic/MDR/MDR.c b/pic/MDR/MDR.c
index 1d1a179..ef46cea 100644
--- a/pic/MDR/MDR.c
+++ b/pic/MDR/MDR.c
@@ -46,6 +46,7 @@
 #define sleep() __asm sleep __endasm
 
 /* variables */
+static uint8_t switches; /* save the last switch state */
 
 /* configuration bits */
 uint16_t __at(_CONFIG1) __CONFIG1 = _FCMEN_ON & /* enable fail-safe clock monitor */
@@ -68,11 +69,13 @@ void init (void) {
 	TRISB |= SWITCH1|SWITCH2; /* switches are inputs (with external pull-ups) */
 	TRISB &= ~(LED|MEMORY_CLK|MEMORY_DATA); /* LED is I2C memory are outputs */
 	led_off(); /* starting state */
-/*
-  IOC |= (SWITCH1|SWITCH2|SWITCH3|SWITCH4); // enable interrupt for the switches
-  GPIE = 1; // enable interrupt on GPIO
-  last_gpio = GPIO; // save current state
 
+	IOCIE = 1; /* enable interrupt on individual GPIO (typo in the lib) */
+	IOCBP |= (SWITCH1|SWITCH2); /* enable interrupt when switch is released */
+	IOCBN |= (SWITCH1|SWITCH2); /* enable interrupt when switch is pressed */
+	switches = PORTB; /* save current switch state */
+
+/*
   T1CON = _T1CKPS1 | _T1CKPS0; // set prescaler to 8
   // 0 is set per default, but just be sure
   TMR1ON = 0; // stop timer 1
@@ -81,16 +84,32 @@ void init (void) {
   TMR1IF = 0; // clear interrupt
   PIE1 = 1; // enable timer 1 interrupt
   PEIE = 1; // enable timer interrupt
-
-  GIE = 1; // enable interrups
 */
 
+	GIE = 1; /* golablly enable interrupts */
 }
 
 /* funcion called on interrupts */
 /* interrupt 0 is only one on PIC16 */
 static void interrupt(void) __interrupt 0
 {
+	if (IOCIF) { /* GPIO interrupt (typo in library?) */
+		if (IOCBF&(SWITCH1|SWITCH2)) { /* switch activity */
+			switches ^= PORTB; /* figure out which switch changed */
+			if (switches&SWITCH1) { /* switch 1 changed */
+				if (PORTB&SWITCH1) { /* switch 1 released */
+					led_off();
+				} else { /* switch 1 pressed */
+					led_on();
+				}
+			}
+			if (switches&SWITCH2) { /* switch 2 changed */
+			}
+			switches = PORTB; /* save current switch state */
+			IOCBF &= ~(SWITCH1|SWITCH2); /* clear switch interrupts */
+		}
+		IOCIF = 0; /* clear GPIO interrupt */
+	}
 }
 
 void main (void)
@@ -98,11 +117,6 @@ void main (void)
 	init(); /* configure micro-controller */
 	led_on();
 	while (1) { /* a microcontroller runs forever */
-		if (PORTB&SWITCH1) {
-			led_off();
-		} else {
-			led_on();
-		}
 //		sleep(); /* sleep to save power */
 	}
 }