Add gyroscope abstraction layer

6 files changed, 114 insertions, 24 deletions

diff --git a/Makefile b/Makefile
index ab206ef..b273b86 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ MCU = atmega88
 
 all: sanduhr.hex
 
-sanduhr.elf: main.c i2c.c i2c.h uart.c uart.h timer.c timer.h
+sanduhr.elf: main.c i2c.c i2c.h uart.c uart.h timer.c timer.h gyroscope.c gyroscope.h
 	avr-gcc -std=gnu99 -mmcu=$(MCU) -Os -o $@ $^
 
 sanduhr.hex: sanduhr.elf
diff --git a/gyroscope.c b/gyroscope.c
new file mode 100644
index 0000000..0f932c2
--- /dev/null
+++ b/gyroscope.c
@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
+
+#include "i2c.h"
+#include "gyroscope.h"
+
+/* device address */
+#define L3GD20 0b11010100
+/* registers */
+#define L3GD20_WHOAMI 0xf
+#define L3GD20_CTRLREG1 0x20
+#define L3GD20_CTRLREG3 0x22
+#define L3GD20_CTRLREG4 0x23
+
+#define sleepwhile(cond) \
+	sleep_enable (); \
+	while (cond) { sleep_cpu (); } \
+	sleep_disable ();
+
+/* the first interrupt is lost */
+volatile bool drdy = true;
+volatile int16_t val[3] = {0, 0, 0};
+
+/* data ready interrupt
+ */
+ISR(PCINT0_vect) {
+	drdy = true;
+}
+
+void gyroscopeInit () {
+	/* set PB1 to input, with pull-up */
+	DDRB = (DDRB & ~((1 << PB1)));
+	PORTB = (PORTB | (1 << PB1));
+	/* enable interrupt PCI0 */
+	PCICR = (1 << PCIE0);
+	/* enable interrupts on PB1/PCINT1 */
+	PCMSK0 = (1 << 1);
+}
+
+/* XXX: make nonblocking */
+void gyroscopeStart () {
+	/* XXX: implement multi-write */
+	/* disable power-down-mode */
+	if (!twWrite (L3GD20, L3GD20_CTRLREG1, 0b00001111)) {
+		printf ("cannot start write\n");
+	}
+	sleepwhile (twr.status == TWST_WAIT);
+	printf ("final twi status was %i\n", twr.status);
+
+	/* enable drdy interrupt */
+	if (!twWrite (L3GD20, L3GD20_CTRLREG3, 0b00001000)) {
+		printf ("cannot start write\n");
+	}
+	sleepwhile (twr.status == TWST_WAIT);
+	printf ("final twi status was %i\n", twr.status);
+
+	/* select 500dps */
+	if (!twWrite (L3GD20, L3GD20_CTRLREG4, 0b00010000)) {
+		printf ("cannot start write\n");
+	}
+	sleepwhile (twr.status == TWST_WAIT);
+	printf ("final twi status was %i\n", twr.status);
+}
+
+bool gyroscopeRead () {
+	if (drdy) {
+		drdy = false;
+
+		if (!twReadMulti (L3GD20, 0x28, (uint8_t *) val, 6)) {
+			printf ("cannot start read\n");
+		}
+
+		return true;
+	} else {
+		return false;
+	}
+}
+
+volatile const int16_t *gyroscopeGet () {
+	return val;
+}
+
diff --git a/gyroscope.h b/gyroscope.h
new file mode 100644
index 0000000..20ef373
--- /dev/null
+++ b/gyroscope.h
@@ -0,0 +1,13 @@
+#ifndef GYROSCOPE_H
+#define GYROSCOPE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+void gyroscopeInit ();
+void gyroscopeStart ();
+bool gyroscopeRead ();
+volatile const int16_t *gyroscopeGet ();
+
+#endif /* GYROSCOPE_H */
+
diff --git a/i2c.h b/i2c.h
index 1381663..abcf5f3 100644
--- a/i2c.h
+++ b/i2c.h
@@ -33,9 +33,6 @@ typedef struct {
 extern volatile twReq twr;
 
 /* i2c device addresses */
-#define L3GD20 0b11010100
-#define L3GD20_WHOAMI 0xf
-#define L3GD20_CTRLREG1 0x20
 #define LIS302DL 0b00111000
 #define LIS302DL_WHOAMI 0xf
 #define LIS302DL_CTRLREG1 0x20
diff --git a/main.c b/main.c
index 4a65c84..fa3b3c1 100644
--- a/main.c
+++ b/main.c
@@ -11,6 +11,7 @@
 #include "i2c.h"
 #include "uart.h"
 #include "timer.h"
+#include "gyroscope.h"
 
 static void ledInit () {
 	/* set led1,led2 to output */
@@ -42,36 +43,29 @@ int main () {
 	ledInit ();
 	twInit ();
 	uartInit ();
+	gyroscopeInit ();
 	set_sleep_mode (SLEEP_MODE_IDLE);
-	
+
 	printf ("initialization done\n");
 
 	/* global interrupt enable */
 	sei ();
-	/* disable power-down-mode */
-	if (!twWrite (LIS302DL, LIS302DL_CTRLREG1, 0b01000111)) {
-		printf ("cannot start write\n");
-	}
-	sleepwhile (twr.status == TWST_WAIT);
-	printf ("final twi status was %i\n", twr.status);
+	gyroscopeStart ();
 
-	timerStart ();
-	unsigned char seconds = 0;
+	//timerStart ();
 	while (1) {
-		uint8_t val[6];
-
-		sleepwhile (!timerHit ());
-		++seconds;
-		printf ("running for %u seconds\n", seconds);
+		//sleepwhile (!timerHit ());
+		//printf ("running for %u seconds\n", seconds);
 
-		if (!twReadMulti (LIS302DL, 0x28, val, 6)) {
-			printf ("cannot start read\n");
-		}
+		sleepwhile (!gyroscopeRead ());
 		sleepwhile (twr.status == TWST_WAIT);
-		printf ("%i/%i/%i\n", (int8_t) val[1], (int8_t) val[3],
-				(int8_t) val[5]);
+
+		volatile const int16_t *val = gyroscopeGet ();
+		printf ("%i/%i/%i\n", val[0], val[1], val[2]);
+
+		_delay_ms (50);
 	}
-	timerStop ();
+	//timerStop ();
 
 	/* global interrupt disable */
 	cli ();
diff --git a/timer.c b/timer.c
index 5830b38..c78ebda 100644
--- a/timer.c
+++ b/timer.c
@@ -6,6 +6,8 @@
 volatile unsigned char count = 0;
 volatile unsigned char hit = 0;
 
+/* XXX: use high-res timer1 for doing this
+ */
 ISR(TIMER0_OVF_vect) {
 	/* there seems to be no mode of operation which disconnects pin OC0A _and_
 	 * clears the value */