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#include "common.h"
#include <stdio.h>
#include <string.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <util/atomic.h>
#include "i2c.h"
#include "accel.h"
/* device address */
#define LIS302DL 0b00111000
/* registers */
#define LIS302DL_WHOAMI 0xf
#define LIS302DL_CTRLREG1 0x20
#define LIS302DL_UNUSED1 0x28
#define LIS302DL_OUTZ 0x2D
/* 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)
/* z value */
static volatile int8_t zval = 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;
/* data ready interrupt
*/
ISR(PCINT1_vect) {
/* empty */
}
void accelInit () {
/* set interrupt lines to input with pull-up */
DDRC = DDRC & ~((1 << DDC0) | (1 << DDC1));
PORTC = PORTC | (1 << PORTC0) | (1 << PORTC1);
/* enable interrupt PCI1 for PCINT8/9 */
PCICR = PCICR | (1 << PCIE1);
/* enable interrupts from port PC0/PC1 aka PCINT8/PCINT9 */
PCMSK1 = (1 << PCINT9) | (1 << PCINT8);
}
/* XXX: make nonblocking */
void accelStart () {
/* configuration:
* disable power-down-mode, enable z-axis
* defaults
* low active, data ready interrupt on int2
*/
uint8_t data[] = {0b01000100, 0b0, 0b10100000};
if (!twRequest (TWM_WRITE, LIS302DL, LIS302DL_CTRLREG1, data,
sizeof (data)/sizeof (*data))) {
printf ("cannot start write\n");
}
sleepwhile (twr.status == TWST_WAIT);
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 () {
/* 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 () {
/* 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;
} else if (twr.status == TWST_ERR) {
printf ("accel i2c error %x at step %i\n", twr.error, twr.step);
reading = false;
}
} else {
if (!((PINC >> PINC1) & 0x1) && twr.status != TWST_WAIT) {
/* new data available in device buffer and bus is free */
if (!twRequest (TWM_READ, LIS302DL, LIS302DL_OUTZ,
(uint8_t *) &zval, sizeof (zval))) {
printf ("cannot start read\n");
} else {
reading = true;
}
}
}
return false;
}
int8_t accelGetZ () {
return zval;
}
uint8_t accelGetShakeCount () {
return shakeCount;
}
void accelResetShakeCount () {
shakeCount = 0;
}
horizon accelGetHorizon () {
return horizonSign;
}
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