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Driver for ultrasonic range meters + example

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UncleRus 2016-10-11 09:28:16 +05:00
parent 29bd8d832a
commit f31ea70e1b
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extras/ultrasonic/ultrasonic.c Normal file
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/*
* Driver for ultrasonic range meters, e.g. HC-SR04, HY-SRF05 and so on
*
* Part of esp-open-rtos
* Copyright (C) 2016 Ruslan V. Uss <unclerus@gmail.com>
* BSD Licensed as described in the file LICENSE
*/
#include "ultrasonic.h"
#include <esp/gpio.h>
#include <espressif/esp_common.h>
#include <stdio.h>
#define TRIGGER_LOW_DELAY 4
#define TRIGGER_HIGH_DELAY 10
#define PING_TIMEOUT 6000
#define ROUNDTRIP 58
void ultrasoinc_init(const ultrasonic_sensor_t *dev)
{
gpio_enable(dev->trigger_pin, GPIO_OUTPUT);
gpio_enable(dev->echo_pin, GPIO_INPUT);
gpio_write(dev->trigger_pin, false);
}
int32_t ultrasoinc_measure_cm(const ultrasonic_sensor_t *dev, uint32_t max_distance)
{
// Ping: Low for 2..4 us, then high 10 us
gpio_write(dev->trigger_pin, false);
sdk_os_delay_us(TRIGGER_LOW_DELAY);
gpio_write(dev->trigger_pin, true);
sdk_os_delay_us(TRIGGER_HIGH_DELAY);
gpio_write(dev->trigger_pin, false);
// Previous ping isn't ended
if (gpio_read(dev->echo_pin))
return ULTRASONIC_ERROR_PING;
// Wait for echo
uint32_t timeout = sdk_system_get_time() + PING_TIMEOUT;
while (!gpio_read(dev->echo_pin))
{
if (sdk_system_get_time() >= timeout)
return ULTRASONIC_ERROR_PING_TIMEOUT;
}
// got echo, measuring
uint32_t echo_start = sdk_system_get_time();
uint32_t time = echo_start;
timeout = echo_start + max_distance * ROUNDTRIP;
while (gpio_read(dev->echo_pin))
{
time = sdk_system_get_time();
if (time >= timeout)
return ULTRASONIC_ERROR_ECHO_TIMEOUT;
}
return (time - echo_start) / ROUNDTRIP;
}