From 254fb0c490c62c0e29518cab2d8b5c90a30b378c Mon Sep 17 00:00:00 2001 From: Lars-Dominik Braun Date: Tue, 9 Dec 2014 12:42:20 +0100 Subject: accel: Fix shake gesture detection --- accel.c | 101 +++++++++++++++++++++++++++++++-------------------------------- accel.h | 1 + common.h | 2 ++ 3 files changed, 53 insertions(+), 51 deletions(-) diff --git a/accel.c b/accel.c index ce44c42..350bf9f 100644 --- a/accel.c +++ b/accel.c @@ -1,6 +1,7 @@ #include "common.h" #include +#include #include #include #include @@ -20,25 +21,27 @@ #define LIS302DL_OUTZ 0x2D /* value for 1g with +-2g max; measured */ -#define ACCEL_1G_POS (55) -#define ACCEL_1G_NEG (-55) +#define ACCEL_1G (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) +/* threshold starting shake detection */ +#define ACCEL_SHAKE_START (70) +/* difference prev and current value to get the current one registered as peak */ +#define ACCEL_SHAKE_REGISTER (120) +/* 100ms for 100Hz data rate */ +#define ACCEL_SHAKE_TIMEOUT (10) /* z value */ -static volatile int8_t zval = 0; +static volatile int8_t zval = 0, zvalnormal = 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; +static int8_t prevShakeVal = 0; +static uint8_t peakCount = 0; + /* horizon position */ /* current */ static horizon horizonSign = HORIZON_NONE; @@ -46,6 +49,7 @@ static horizon horizonSign = HORIZON_NONE; static uint8_t horizonStable = 0; /* previous measurement */ static horizon horizonPrevSign = HORIZON_NONE; + /* currently reading from i2c */ static bool reading = false; @@ -91,49 +95,32 @@ void accelStart () { /* register shake gesture * - * “shake” means a peak in one direction followed by another one in the other - * direction. called for every data set pulled. + * “shake” means three peaks in directions 1, -1, 1 */ static void accelProcessShake () { - /* 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 { + if (shakeTimeout > 0) { + --shakeTimeout; + if (abs ((int16_t) prevShakeVal - (int16_t) zvalnormal) > ACCEL_SHAKE_REGISTER) { + ++peakCount; shakeTimeout = ACCEL_SHAKE_TIMEOUT; + prevShakeVal = zvalnormal; + } else if (sign (prevShakeVal) == sign (zvalnormal) && + abs (zvalnormal) > abs (prevShakeVal)) { + /* actually we did not measure the peak yet */ + prevShakeVal = zvalnormal; } - 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; + if (shakeTimeout == 0) { + /* just timed out, can register gesture now. XXX: why 3? */ + shakeCount += peakCount/3; } } + + /* start shake detection */ + if (shakeTimeout == 0 && abs (zvalnormal) > ACCEL_SHAKE_START) { + shakeTimeout = ACCEL_SHAKE_TIMEOUT; + peakCount = 1; + prevShakeVal = zvalnormal; + } } /* register horizon change @@ -142,12 +129,12 @@ static void accelProcessShake () { */ static void accelProcessHorizon () { /* measuring approximately 1g */ - if (zval > (ACCEL_1G_POS - ACCEL_1G_OFF) && - zval < (ACCEL_1G_POS + ACCEL_1G_OFF) && + if (zval > (ACCEL_1G - ACCEL_1G_OFF) && + zval < (ACCEL_1G + 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) && + } else if (zval < (-ACCEL_1G + ACCEL_1G_OFF) + && zval > (-ACCEL_1G - ACCEL_1G_OFF) && horizonPrevSign == HORIZON_NEG && horizonSign != HORIZON_NEG) { ++horizonStable; } else { @@ -167,6 +154,14 @@ bool accelProcess () { reading = false; if (twr.status == TWST_OK) { accelProcessHorizon (); + + /* calculate normalized z (i.e. without earth gravity component) */ + if (horizonSign == HORIZON_NEG) { + zvalnormal = zval - (-ACCEL_1G); + } else if (horizonSign == HORIZON_POS) { + zvalnormal = zval - ACCEL_1G; + } + accelProcessShake (); /* new data transfered */ return true; @@ -194,6 +189,10 @@ int8_t accelGetZ () { return zval; } +int8_t accelGetNormalizedZ () { + return zvalnormal; +} + uint8_t accelGetShakeCount () { return shakeCount; } diff --git a/accel.h b/accel.h index 092bd1e..b984fdd 100644 --- a/accel.h +++ b/accel.h @@ -10,6 +10,7 @@ void accelInit (); void accelStart (); bool accelProcess (); int8_t accelGetZ (); +int8_t accelGetNormalizedZ (); uint8_t accelGetShakeCount (); void accelResetShakeCount (); horizon accelGetHorizon (); diff --git a/common.h b/common.h index eced70e..e879e92 100644 --- a/common.h +++ b/common.h @@ -44,5 +44,7 @@ enum { void shutdownError (); +#define sign(x) ((x < 0) ? -1 : 1) + #endif /* COMMON_H */ -- cgit v1.2.3