Driver for ultrasonic range meters + example

examples/ultrasonic/Makefile

@@ -0,0 +1,4 @@
+PROGRAM = ultrasonic
+EXTRA_COMPONENTS = extras/ultrasonic
+
+include ../../common.mk

examples/ultrasonic/main.c

@@ -0,0 +1,60 @@
+/*
+ * Example of using ultrasonic rnaghe meter like HC-SR04
+ *
+ * Part of esp-open-rtos
+ * Copyright (C) 2016 Ruslan V. Uss <unclerus@gmail.com>
+ * BSD Licensed as described in the file LICENSE
+ */
+#include <espressif/esp_common.h>
+#include <esp/uart.h>
+#include <esp/gpio.h>
+#include <ultrasonic/ultrasonic.h>
+
+#define TRIGGER_PIN 5
+#define ECHO_PIN    4
+
+#define MAX_DISTANCE_CM 500 // 5m max
+
+void delay_ms(uint32_t ms)
+{
+    for (uint32_t i = 0; i < ms; i ++)
+        sdk_os_delay_us(1000);
+}
+
+void user_init()
+{
+    uart_set_baud(0, 115200);
+    printf("SDK version : %s\n", sdk_system_get_sdk_version());
+
+    ultrasonic_sensor_t sensor = {
+        .trigger_pin = TRIGGER_PIN,
+        .echo_pin = ECHO_PIN
+    };
+
+    ultrasoinc_init(&sensor);
+
+    while (true)
+    {
+        int32_t distance = ultrasoinc_measure_cm(&sensor, MAX_DISTANCE_CM);
+        if (distance < 0)
+        {
+            printf("Error: ");
+            switch (distance)
+            {
+                case ULTRASONIC_ERROR_PING:
+                    printf("Cannot ping (device is in invalid state)\n");
+                    break;
+                case ULTRASONIC_ERROR_PING_TIMEOUT:
+                    printf("Ping timeout (no device found)\n");
+                    break;
+                case ULTRASONIC_ERROR_ECHO_TIMEOUT:
+                    printf("Echo timeout (i.e. distance too big)\n");
+                    break;
+            }
+        }
+        else
+            printf("Distance: %d cm, %.02f m\n", distance, distance / 100.0);
+
+        delay_ms(200);
+    }
+}

extras/ultrasonic/component.mk

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+# Component makefile for extras/ultrasonic
+
+# expected anyone using this driver includes it as 'ultrasonic/ultrasonic.h'
+INC_DIRS += $(ultrasonic_ROOT)..
+
+# args for passing into compile rule generation
+ultrasonic_SRC_DIR = $(ultrasonic_ROOT)
+
+$(eval $(call component_compile_rules,ultrasonic))

extras/ultrasonic/ultrasonic.c

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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;
+}

extras/ultrasonic/ultrasonic.h

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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
+ */
+#ifndef EXTRAS_ULTRASONIC_H_
+#define EXTRAS_ULTRASONIC_H_
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define ULTRASONIC_ERROR_PING         (-1)
+#define ULTRASONIC_ERROR_PING_TIMEOUT (-2)
+#define ULTRASONIC_ERROR_ECHO_TIMEOUT (-3)
+
+/**
+ * Device descriptor
+ */
+typedef struct
+{
+    uint8_t trigger_pin;
+    uint8_t echo_pin;
+} ultrasonic_sensor_t;
+
+/**
+ * Init ranging module
+ * \param dev Pointer to the device descriptor
+ */
+void ultrasoinc_init(const ultrasonic_sensor_t *dev);
+
+/**
+ * Measure distance
+ * \param dev Pointer to the device descriptor
+ * \param max_distance Maximal distance to measure, centimeters
+ * \return Distance in centimeters or ULTRASONIC_ERROR_xxx if error occured
+ */
+int32_t ultrasoinc_measure_cm(const ultrasonic_sensor_t *dev, uint32_t max_distance);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* EXTRAS_ULTRASONIC_H_ */