mirror of
https://github.com/RIOT-OS/RIOT.git
synced 2024-12-29 04:50:03 +01:00
100 lines
2.1 KiB
C
100 lines
2.1 KiB
C
/*
|
|
* Copyright (C) 2018 Freie Universität Berlin
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU Lesser
|
|
* General Public License v2.1. See the file LICENSE in the top level
|
|
* directory for more details.
|
|
*/
|
|
|
|
/**
|
|
* @ingroup drivers_srf04
|
|
* @{
|
|
*
|
|
* @file
|
|
* @brief driver for srf04 ultra sonic range finder
|
|
*
|
|
* @author Semjon Kerner <semjon.kerner@fu-berlin.de>
|
|
*
|
|
* @}
|
|
*/
|
|
|
|
#include "srf04.h"
|
|
#include "srf04_params.h"
|
|
|
|
#define ENABLE_DEBUG 0
|
|
#include "debug.h"
|
|
|
|
#define SRF04_DISTANCE (584U)
|
|
#define SRF04_SAMPLE_PERIOD (50U * US_PER_MS)
|
|
|
|
static void _cb(void *arg)
|
|
{
|
|
uint32_t t = xtimer_now_usec();
|
|
|
|
srf04_t *dev = (srf04_t *)arg;
|
|
|
|
if (dev->distance > SRF04_ERR_MEASURING) {
|
|
dev->distance = SRF04_ERR_MEASURING;
|
|
dev->time = t;
|
|
}
|
|
else {
|
|
gpio_irq_disable(dev->p.echo);
|
|
dev->distance = (t - dev->time);
|
|
}
|
|
}
|
|
|
|
int srf04_init(srf04_t *dev, const srf04_params_t *params)
|
|
{
|
|
dev->p = *params;
|
|
|
|
dev->distance = SRF04_ERR_INVALID;
|
|
dev->time = 0;
|
|
|
|
if (gpio_init(dev->p.trigger, GPIO_OUT) != 0) {
|
|
DEBUG("[srf04] Error: could not initialize GPIO trigger pin\n");
|
|
return SRF04_ERR_GPIO;
|
|
}
|
|
|
|
if (gpio_init_int(dev->p.echo, GPIO_IN, GPIO_BOTH, _cb, (void *)dev) != 0) {
|
|
DEBUG("[srf04] Error: could not initialize GPIO echo pin\n");
|
|
return SRF04_ERR_GPIO;
|
|
}
|
|
|
|
gpio_irq_disable(dev->p.echo);
|
|
|
|
return SRF04_OK;
|
|
}
|
|
|
|
void srf04_trigger(const srf04_t *dev)
|
|
{
|
|
if (dev->distance == SRF04_ERR_MEASURING) {
|
|
return;
|
|
}
|
|
|
|
gpio_irq_enable(dev->p.echo);
|
|
|
|
gpio_set(dev->p.trigger);
|
|
xtimer_usleep(10);
|
|
gpio_clear(dev->p.trigger);
|
|
}
|
|
|
|
int srf04_read(const srf04_t *dev)
|
|
{
|
|
return dev->distance;
|
|
}
|
|
|
|
int srf04_get_distance(const srf04_t *dev)
|
|
{
|
|
/* Trigger new reading */
|
|
srf04_trigger(dev);
|
|
|
|
/* Give the sensor the required time for sampling */
|
|
xtimer_usleep(SRF04_SAMPLE_PERIOD);
|
|
|
|
/* Get the result */
|
|
if (dev->distance >= SRF04_OK) {
|
|
return ((dev->distance * 100) / SRF04_DISTANCE);
|
|
}
|
|
return dev->distance;
|
|
}
|