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-rw-r--r--accel.c109
-rw-r--r--accel.h4
-rw-r--r--main.c6
3 files changed, 118 insertions, 1 deletions
diff --git a/accel.c b/accel.c
index ede53ff..9e3bda4 100644
--- a/accel.c
+++ b/accel.c
@@ -17,8 +17,33 @@
#define LIS302DL_CTRLREG1 0x20
#define LIS302DL_UNUSED1 0x28
+/* value for 1g with +-2g max; measured */
+#define ACCEL_1G_POS (55)
+#define ACCEL_1G_NEG (-55)
+/* offset for horizon detection */
+#define ACCEL_1G_OFF (5)
+/* shake detection values; 2g for +-2g max */
+#define ACCEL_SHAKE_POS (INT8_MAX)
+#define ACCEL_SHAKE_NEG (INT8_MIN)
+/* 250ms for 100Hz data rate */
+#define ACCEL_SHAKE_TIMEOUT (25)
+
/* 0, 2 and 4 are zero, as they contain the dummy register’s content */
static volatile int8_t val[6] = {0, 0, 0, 0, 0, 0};
+/* number of times shaken (i.e. peak level measured) */
+static uint8_t shakeCount = 0;
+/* if max in one direction direction has been detected give it some time to
+ * wait for max in the other direction */
+static uint8_t shakeTimeout = 0;
+/* sign of last shake peak */
+static enum {SHAKE_NONE, SHAKE_POS, SHAKE_NEG} shakeSign = SHAKE_NONE;
+/* horizon position */
+/* current */
+static horizon horizonSign = HORIZON_NONE;
+/* how long has sign been stable? */
+static uint8_t horizonStable = 0;
+/* previous measurement */
+static horizon horizonPrevSign = HORIZON_NONE;
/* currently reading from i2c */
static bool reading = false;
@@ -55,9 +80,85 @@ void accelStart () {
printf ("final twi status was %i\n", twr.status);
}
+/* register shake gesture
+ *
+ * “shake” means a peak in one direction followed by another one in the other
+ * direction. called for every data set pulled.
+ */
+static void accelProcessShake () {
+ const int8_t zval = val[5];
+ /* detect shake if:
+ * a) horizon is positive and accel z value is >= ACCEL_SHAKE_POS
+ * b) horizon is negative and accel z value is >= ACCEL_SHAKE_POS offset by
+ * the value for 1g (negative)
+ * (same for negative horizon)
+ */
+ if (((zval >= ACCEL_SHAKE_POS &&
+ horizonSign == HORIZON_POS) ||
+ (zval >= (ACCEL_SHAKE_POS + ACCEL_1G_NEG) &&
+ horizonSign == HORIZON_NEG)) &&
+ shakeSign != SHAKE_POS) {
+ /* if we did not time out (i.e. max in other direction has been
+ * detected) register shake */
+ if (shakeTimeout > 0) {
+ ++shakeCount;
+ /* correctly detect double/triple/… shakes; setting this to
+ * ACCEL_SHAKE_TIMEOUT yields wrong results */
+ shakeTimeout = 0;
+ } else {
+ shakeTimeout = ACCEL_SHAKE_TIMEOUT;
+ }
+ shakeSign = SHAKE_POS;
+ } else if (((zval <= ACCEL_SHAKE_NEG &&
+ horizonSign == HORIZON_NEG) ||
+ (zval <= (ACCEL_SHAKE_NEG + ACCEL_1G_POS) &&
+ horizonSign == HORIZON_POS)) &&
+ shakeSign != SHAKE_NEG) {
+ if (shakeTimeout > 0) {
+ ++shakeCount;
+ shakeTimeout = 0;
+ } else {
+ shakeTimeout = ACCEL_SHAKE_TIMEOUT;
+ }
+ shakeSign = SHAKE_NEG;
+ } else {
+ if (shakeTimeout > 0) {
+ --shakeTimeout;
+ }
+ }
+}
+
+/* register horizon change
+ *
+ * i.e. have we been turned upside down?
+ */
+static void accelProcessHorizon () {
+ const int8_t zval = val[5];
+ /* measuring approximately 1g */
+ if (zval > (ACCEL_1G_POS - ACCEL_1G_OFF) &&
+ zval < (ACCEL_1G_POS + ACCEL_1G_OFF) &&
+ horizonPrevSign == HORIZON_POS && horizonSign != HORIZON_POS) {
+ ++horizonStable;
+ } else if (zval < (ACCEL_1G_NEG + ACCEL_1G_OFF)
+ && zval > (ACCEL_1G_NEG - ACCEL_1G_OFF) &&
+ horizonPrevSign == HORIZON_NEG && horizonSign != HORIZON_NEG) {
+ ++horizonStable;
+ } else {
+ horizonStable = 0;
+ }
+ /* make sure its not just shaking */
+ if (horizonStable > 5) {
+ horizonSign = horizonPrevSign;
+ horizonStable = 0;
+ }
+ horizonPrevSign = zval >= 0 ? HORIZON_POS : HORIZON_NEG;
+}
+
bool accelProcess () {
if (reading) {
if (twr.status == TWST_OK) {
+ accelProcessHorizon ();
+ accelProcessShake ();
/* new data transfered */
reading = false;
return true;
@@ -85,3 +186,11 @@ volatile const int8_t *accelGet () {
return val;
}
+const uint8_t accelGetShakeCount () {
+ return shakeCount;
+}
+
+const horizon accelGetHorizon () {
+ return horizonSign;
+}
+
diff --git a/accel.h b/accel.h
index 7d82933..6c1022d 100644
--- a/accel.h
+++ b/accel.h
@@ -4,10 +4,14 @@
#include <stdbool.h>
#include <stdint.h>
+typedef enum {HORIZON_NONE, HORIZON_POS, HORIZON_NEG} horizon;
+
void accelInit ();
void accelStart ();
bool accelProcess ();
volatile const int8_t *accelGet ();
+const uint8_t accelGetShakeCount ();
+const horizon accelGetHorizon ();
#endif /* ACCEL_H */
diff --git a/main.c b/main.c
index 608327c..84aa75e 100644
--- a/main.c
+++ b/main.c
@@ -60,9 +60,11 @@ int main () {
gyroStart ();
accelStart ();
+#if 0
speakerStart ();
_delay_ms (200);
speakerStop ();
+#endif
timerStart ();
bool checkGyro = false;
@@ -81,7 +83,9 @@ int main () {
sleep_cpu ();
sleep_disable ();
}
- printf ("ticks=%i\n", gyroGetZTicks ());
+
+ printf ("t=%i, h=%i, s=%i\n", gyroGetZTicks (), accelGetHorizon (),
+ accelGetShakeCount ());
#if 0
volatile const int32_t *gyroval = gyroGetAccum ();
volatile const int16_t *gyroraw = gyroGetRaw ();