From 9883e2d8d6c6ca61c39704e56504597c6bc5e63b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Mon, 14 Oct 2013 13:36:25 +0200
Subject: [PATCH] added function to calculate IR pulse times

---
 src/main.c | 41 ++++++++++++++++++++++++++++++-----------
 src/main.h |  1 +
 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/src/main.c b/src/main.c
index dd4b4fa..60fdaf6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -16,9 +16,10 @@ volatile uint8_t timer2_ovf = 0; /* to measure fan speed using timer 2 */
 static const uint16_t TIMER2_PRESCALE[8] = {0,1,8,32,64,128,256,1024}; /* timer 2 CS2[2:0] values */
 volatile uint16_t tachometer = 0; /* the tachometer time (from timer) */
 volatile uint8_t ir; /* IR signal state, to measure IR code */
-volatile uint8_t pulse_i = 1; /* pulse index */
-# define PULSE_MAX 64 /* maximum number of pulses to save */
-volatile uint16_t pulse[PULSE_MAX]; /* pulse times (from timer) */
+static const uint16_t TIMER1_PRESCALE[8] = {0,1,8,64,256,1024,0,0}; /* timer 1 CS1[2:0] values */
+volatile uint8_t pulse = 1; /* pulse index within the burst */
+#define PULSE_MAX 128 /* maximum number of pulses to save */
+volatile uint16_t burst[PULSE_MAX]; /* pulse times forming a burst (from timer) */
 
 
 /* power ok interrupt */
@@ -33,12 +34,12 @@ ISR(PCINT0_vect) { /* PCI0 Interrupt Vector for PCINT[7:0] */
 		}
 	} else if (ir!=(PINB&(1<<IR))) { /* did the IR pin state changed */
 		ir = PINB&(1<<IR); /* save new state */
-		if (pulse_i>0) { /* save pulse, except the first */
-			pulse[pulse_i-1] = TCNT1;
-			pulse[pulse_i] = 0;
+		if (pulse>0) { /* save pulse, except the first */
+			burst[pulse-1] = TCNT1;
+			burst[pulse] = 0;
 		}
-		if (pulse_i<PULSE_MAX-1) { /* prepare to save next pulse */
-			pulse_i++;
+		if (pulse<PULSE_MAX-1) { /* prepare to save next pulse */
+			pulse++;
 		}
 		TCNT1 = 0; /* clear timer 1 */
 	}
@@ -65,9 +66,10 @@ ISR(TIMER2_OVF_vect) { /* timer 2 overflow interrupt vector */
 
 /* timer 1 interrupt used to measure IR pulse */
 ISR(TIMER1_COMPA_vect) { /* timer 1 OCR1A match interrupt vector */
-	if (pulse_i>0) {
-		pulse_i = 0;
+	if (pulse>0) {
+		pulse2us();
 		OCR0A = ~OCR0A;
+		pulse = 0;
 	}
 }
 
@@ -127,7 +129,8 @@ static void ioinit(void)
 	/* clock/8 prescaler, offers most precision for 15ms (up to 28.5ms) */
 	TCCR1B |= (1<<CS11);
 	TCCR1B &= ~((1<<CS12)|(1<<CS10));
-	OCR1A = (uint32_t)(15*F_CPU)/(1000*8); /* set clear time to 15 ms (no IR toggle should be longer) */
+	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10];
+	OCR1A = (uint32_t)(15*F_CPU)/(1000*prescale); /* set clear time to 15 ms (no IR toggle should be longer) */
 	TIFR1 &= ~(1<<OCF1A); /* clear timer 1 overflow interrupt flag */
 	TIMSK1 |= (1<<OCIE1A); /* enable timer 1 overflow interrupt */
 
@@ -145,6 +148,22 @@ static void ioinit(void)
 	sei(); /* enable interrupts */
 }
 
+/* convert burst to micro-seconds */
+static void pulse2us(void)
+{
+	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10]; /* timer 1 presacler */
+	uint16_t tick = F_CPU/(1000*prescale); /* ticks per ms */
+	//uint16_t time; /* pulse time in us */
+
+	if (0==prescale) {
+		return;
+	}
+	for (uint8_t i=0; i<pulse; i++) {
+		burst[i] = (burst[i]*1000UL)/tick;
+		printf("pulse %u: %uus\n",i,burst[i]);
+	}
+}
+
 int main(void)
 {
 	ioinit(); /* initialize IOs */
diff --git a/src/main.h b/src/main.h
index 1f92129..9018376 100644
--- a/src/main.h
+++ b/src/main.h
@@ -17,3 +17,4 @@
 #define CH2_5 PD7
 
 static void ioinit(void);
+static void pulse2us(void);