uint16_t acc_magnitude(int8_t* angle)
{
int16_t acc[3], a, alpha;
/* briefly turn on accelerometer */
acc_write(ACC_REG_CTRL_REG1, 0x97);
timer_wait(MILLISECONDS(2));
acc_read(ACC_REG_OUT_X, sizeof(acc), (uint8_t*)&acc);
acc_write(ACC_REG_CTRL_REG1, 0x00);
/* get acceleration vector magnitude */
a = sqrt32(
((int)acc[0])*acc[0] +
((int)acc[1])*acc[1] +
((int)acc[2])*acc[2]
)/64;
/* calculate tag angle */
if(angle)
{
if(!a)
alpha = 127;
else
{
alpha = (acc[2]*2)/a;
if(alpha>127)
alpha=127;
else
if(alpha<-127)
alpha=-127;
}
*angle = asin7deg(alpha);
}
return a;
}
uint8_t acc_init(void)
{
int i;
uint8_t data;
/* initialize GPIO */
nrf_gpio_cfg_input(CONFIG_ACC_INT1, NRF_GPIO_PIN_NOPULL);
nrf_gpio_cfg_input(CONFIG_ACC_MISO, NRF_GPIO_PIN_NOPULL);
nrf_gpio_cfg_output(CONFIG_ACC_MOSI);
nrf_gpio_cfg_output(CONFIG_ACC_SCK);
nrf_gpio_cfg_output(CONFIG_ACC_nCS);
/* mark inactive by default */
nrf_gpio_pin_set(CONFIG_ACC_nCS);
/* configure peripheral */
SPI_ACC->PSELMISO = CONFIG_ACC_MISO;
SPI_ACC->PSELMOSI = CONFIG_ACC_MOSI;
SPI_ACC->PSELSCK = CONFIG_ACC_SCK;
/* configure accelerometer for 8MHz */
SPI_ACC->FREQUENCY = SPI_FREQUENCY_FREQUENCY_M8;
SPI_ACC->CONFIG =
(SPI_CONFIG_ORDER_MsbFirst << SPI_CONFIG_ORDER_Pos) |\
(SPI_CONFIG_CPHA_Trailing << SPI_CONFIG_CPHA_Pos) |\
(SPI_CONFIG_CPOL_ActiveLow << SPI_CONFIG_CPOL_Pos);
/* reset events */
SPI_ACC->EVENTS_READY = 0U;
/* enable SPI accelerometer peripheral */
SPI_ACC->ENABLE =
(SPI_ENABLE_ENABLE_Enabled << SPI_ENABLE_ENABLE_Pos);
/* check accelerometer read */
acc_read(ACC_REG_WHO_AM_I, sizeof(data), &data);
if(data!=0x33)
return 1;
/* initialize accelerometer */
for(i=0; i<ACC_INIT_COUNT; i++)
acc_write(g_acc_init[i][0], g_acc_init[i][1]);
return 0;
}
/**
* Flushes the content of the output-buffer.
* The content of achat_channel::sendbuffer is written into achat_channel::fd.
*
* @param chan The channel
* @return If the complete content of the output-buffer was written into the
* filedescriptor achat_rc::ACHAT_RC_OK is returned. When there are
* still some pending data left, achat_rc::ACHAT_RC_PENDING is returned.
*/
achat_rc
acc_flush(struct achat_channel *chan)
{
void *buf;
ssize_t bwritten, bsize;
achat_rc ret;
int error;
ACC_CHKPARAM(chan != NULL);
buf = acc_bufferptr(chan->sendbuffer);
bsize = acc_bufferlen(chan->sendbuffer);
if (bsize <= 0) {
/* Nothing to do */
return ACHAT_RC_OK;
}
bwritten = acc_write(chan->fd, buf, bsize);
error = errno;
if (bwritten > 0) {
achat_rc rc;
/* Remove chunk of data from buffer */
rc = acc_bufferconsume(chan->sendbuffer, bwritten);
if (rc != ACHAT_RC_OK)
return ACHAT_RC_ERROR;
}
if (bwritten < 0)
ret = (error == EAGAIN) ? ACHAT_RC_PENDING : ACHAT_RC_ERROR;
else /* bwritten > 0 */
ret = (bwritten == bsize) ? ACHAT_RC_OK : ACHAT_RC_PENDING;
if (ret == ACHAT_RC_PENDING && chan->event) {
event_add(chan->event, NULL);
ret = ACHAT_RC_OK;
}
return ret;
}