Add wakeup source mechanism

Should reduce amount of cpu wakeups with expensive computations.

9 files changed, 67 insertions, 24 deletions

diff --git a/Makefile b/Makefile
index 56998e1..6d1783d 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CFLAGS=-Os -Wall -Wextra
 
 all: sanduhr.hex
 
-sanduhr.elf: main.c i2c.c i2c.h uart.c uart.h timer.c timer.h gyro.c gyro.h accel.c accel.h common.h pwm.c pwm.h ui.c ui.h
+sanduhr.elf: main.c i2c.c i2c.h uart.c uart.h timer.c common.c timer.h gyro.c gyro.h accel.c accel.h common.h pwm.c pwm.h ui.c ui.h
 	avr-gcc -std=gnu99 -mmcu=$(MCU) $(CFLAGS) -o $@ $^
 
 sanduhr.hex: sanduhr.elf
diff --git a/accel.c b/accel.c
index bd73043..ed2aa81 100644
--- a/accel.c
+++ b/accel.c
@@ -51,7 +51,13 @@ static bool reading = false;
 /* data ready interrupt
  */
 ISR(PCINT1_vect) {
-	/* empty */
+	const bool interrupt = (PINC >> PINC1) & 0x1;
+	/* low-active */
+	if (!interrupt) {
+		enableWakeup (WAKE_ACCEL);
+	} else {
+		disableWakeup (WAKE_ACCEL);
+	}
 }
 
 void accelInit () {
@@ -79,6 +85,7 @@ void accelStart () {
 	}
 	sleepwhile (twr.status == TWST_WAIT);
 	puts ("accelStart done");
+	disableWakeup (WAKE_I2C);
 }
 
 /*	register shake gesture
@@ -154,25 +161,26 @@ static void accelProcessHorizon () {
 }
 
 bool accelProcess () {
-	if (reading) {
+	if (reading && shouldWakeup (WAKE_I2C)) {
+		disableWakeup (WAKE_I2C);
+		reading = false;
 		if (twr.status == TWST_OK) {
 			accelProcessHorizon ();
 			accelProcessShake ();
 			/* new data transfered */
-			reading = false;
 			return true;
 		} else if (twr.status == TWST_ERR) {
 			puts ("accel i2c error: ");
 			fwrite ((void *) &twr.error, sizeof (twr.error), 1, stdout);
-			reading = false;
 		}
 	} else {
-		if (!((PINC >> PINC1) & 0x1) && twr.status == TWST_OK) {
+		if (shouldWakeup (WAKE_ACCEL) && twr.status == TWST_OK) {
 			/* new data available in device buffer and bus is free */
 			if (!twRequest (TWM_READ, LIS302DL, LIS302DL_OUTZ,
 					(uint8_t *) &zval, sizeof (zval))) {
 				puts ("cannot start read");
 			} else {
+				/* wakeup source is disabled by isr to prevent race condition */
 				reading = true;
 			}
 		}
diff --git a/common.c b/common.c
new file mode 100644
index 0000000..e3f3195
--- /dev/null
+++ b/common.c
@@ -0,0 +1,4 @@
+#include "common.h"
+
+volatile uint8_t wakeup = 0;
+
diff --git a/common.h b/common.h
index 5957da3..fb53d4d 100644
--- a/common.h
+++ b/common.h
@@ -23,5 +23,27 @@
 		} \
 	}
 
+#include <stdbool.h>
+
+/* global wakeup flag, incremented by functions that interact with the main
+ * loop (i.e. not pwm) */
+extern volatile uint8_t wakeup;
+
+/* wakeup sources */
+enum {
+	WAKE_ACCEL = 0,
+	WAKE_GYRO = 1,
+	WAKE_I2C = 2,
+	WAKE_TIMER = 3,
+};
+
+#define shouldWakeup(x) (wakeup & (1 << x))
+#define enableWakeup(x) wakeup |= 1 << x;
+#include <util/atomic.h>
+#define disableWakeup(x) \
+	ATOMIC_BLOCK (ATOMIC_FORCEON) { \
+		wakeup &= ~(1 << x); \
+	}
+
 #endif /* COMMON_H */
 
diff --git a/gyro.c b/gyro.c
index f31385d..fdf2d1f 100644
--- a/gyro.c
+++ b/gyro.c
@@ -31,7 +31,13 @@ static bool reading = false;
 /* data ready interrupt
  */
 ISR(PCINT0_vect) {
-	/* empty */
+	const bool interrupt = (PINB >> PINB1) & 0x1;
+	/* high-active */
+	if (interrupt) {
+		enableWakeup (WAKE_GYRO);
+	} else {
+		disableWakeup (WAKE_GYRO);
+	}
 }
 
 void gyroInit () {
@@ -60,6 +66,7 @@ void gyroStart () {
 	}
 	sleepwhile (twr.status == TWST_WAIT);
 	puts ("gyroStart done");
+	disableWakeup (WAKE_I2C);
 }
 
 /*	calculate ticks for z rotation
@@ -84,7 +91,9 @@ static void gyroProcessTicks () {
 /*	process gyro sensor data, returns true if new data is available
  */
 bool gyroProcess () {
-	if (reading) {
+	if (reading && shouldWakeup (WAKE_I2C)) {
+		disableWakeup (WAKE_I2C);
+		reading = false;
 		if (twr.status == TWST_OK) {
 			/* new data transfered, process it */
 			/* poor man's noise filter */
@@ -92,19 +101,18 @@ bool gyroProcess () {
 				zaccum += zval;
 			}
 			gyroProcessTicks ();
-			reading = false;
 			return true;
 		} else if (twr.status == TWST_ERR) {
 			puts ("gyro i2c error");
-			reading = false;
 		}
 	} else {
-		if (((PINB >> PINB1) & 0x1) && twr.status == TWST_OK) {
+		if (shouldWakeup (WAKE_GYRO) && twr.status == TWST_OK) {
 			/* new data available in device buffer and bus is free */
 			if (!twRequest (TWM_READ, L3GD20, L3GD20_OUTZ,
 					(uint8_t *) &zval, sizeof (zval))) {
 				puts ("cannot start read");
 			} else {
+				/* wakeup source is disabled by isr to prevent race condition */
 				reading = true;
 			}
 		}
diff --git a/i2c.c b/i2c.c
index 00dee14..a94b3a0 100644
--- a/i2c.c
+++ b/i2c.c
@@ -255,5 +255,8 @@ ISR(TWI_vect) {
 			assert (0 && "nope\n");
 			break;
 	}
+	if (twr.status == TWST_ERR || twr.status == TWST_OK) {
+		enableWakeup (WAKE_I2C);
+	}
 }
 
diff --git a/pwm.c b/pwm.c
index 568ed73..944720e 100644
--- a/pwm.c
+++ b/pwm.c
@@ -19,7 +19,6 @@ static const uint8_t offbits[2] = {(uint8_t) ~((1 << PB6) | (1 << PB7)),
 		(uint8_t) ~((1 << PD2) | (1 << PD3) | (1 << PD4) | (1 << PD5) | (1 << PD6))};
 
 ISR(TIMER0_COMPA_vect) {
-#warning "speaker works now, led1 and 2 do not work"
 	if (speakerCount > 0) {
 		--speakerCount;
 		/* stop speaker after beep */
@@ -36,6 +35,8 @@ ISR(TIMER0_COMPA_vect) {
 
 	/* auto wrap-around */
 	count = (count+1) & (PWM_MAX_BRIGHTNESS-1);
+
+	/* no wakeup */
 }
 
 static uint8_t ledToArray (const uint8_t i) {
@@ -105,7 +106,7 @@ void pwmSet (const uint8_t i, const uint8_t value) {
 	}
 }
 
-void speakerStart (const speakerMode mode) {
+void speakerStart (const speakerMode mode __unused__) {
 	/* 12.8ms */
 	speakerCount = 100;
 	for (uint8_t i = 0; i < PWM_MAX_BRIGHTNESS; i += 2) {
diff --git a/timer.c b/timer.c
index ce30b60..8de6157 100644
--- a/timer.c
+++ b/timer.c
@@ -22,13 +22,17 @@ ISR(TIMER1_COMPA_vect) {
 	time += OCR1A * US_PER_TICK;
 	if (hits == maxhits-1) {
 		OCR1A = lastcount;
+	} else if (hits >= maxhits) {
+		enableWakeup (WAKE_TIMER);
 	}
 }
 
 /*	Check if timer was hit, return time since last restart or 0 if not hit yet
  */
 uint32_t timerHit () {
-	if (hits >= maxhits) {
+	if (shouldWakeup (WAKE_TIMER)) {
+		disableWakeup (WAKE_TIMER);
+
 		const uint32_t ret = time;
 		/* reset timer, start again */
 		hits = 0;
diff --git a/ui.c b/ui.c
index 7bd393d..9175133 100644
--- a/ui.c
+++ b/ui.c
@@ -266,14 +266,6 @@ static void doInit () {
 	}
 }
 
-/*	Sleep CPU
- */
-static void cpuSleep () {
-	sleep_enable ();
-	sleep_cpu ();
-	sleep_disable ();
-}
-
 /*	Main loop
  */
 void uiLoop () {
@@ -329,7 +321,7 @@ void uiLoop () {
 
 	while (1) {
 		processSensors ();
-		
+
 		horizon newh = accelGetHorizon ();
 		if (newh != h) {
 			horizonChanged = true;
@@ -367,7 +359,8 @@ void uiLoop () {
 				assert (0 && "invalid ui mode");
 				break;
 		}
-		cpuSleep ();
+
+		sleepwhile (wakeup == 0);
 
 #if 0
 		printf ("t=%i, h=%i, s=%i\n", gyroGetZTicks (), accelGetHorizon (),