Merge pull request #2990 from LudwigOrtmann/pr/dht

drivers/dht: initial import

drivers/Makefile.include

@@ -10,6 +10,9 @@ endif
 ifneq (,$(filter cc110x_legacy,$(USEMODULE)))
     USEMODULE_INCLUDES += $(RIOTBASE)/drivers/cc110x_legacy/include
 endif
+ifneq (,$(filter dht,$(USEMODULE)))
+    USEMODULE_INCLUDES += $(RIOTBASE)/drivers/dht/include
+endif
 ifneq (,$(filter at86rf231,$(USEMODULE)))
     USEMODULE_INCLUDES += $(RIOTBASE)/drivers/at86rf231/include
 endif

drivers/dht/Makefile

@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base

drivers/dht/dht.c

@@ -0,0 +1,199 @@
+/*
+ * Copyright 2015 Ludwig Ortmann
+ * Copyright 2015 Christian Mehlis
+ *
+ * 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     driver_dht
+ * @{
+ *
+ * @file
+ * @brief       Device driver implementation for the DHT 11 and 22
+ *              temperature and humidity sensor
+ *
+ * @author      Ludwig Ortmann <ludwig.ortmann@fu-berlin.de>
+ * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
+ *
+ * @}
+ */
+
+#include <stdint.h>
+
+#include "hwtimer.h"
+#include "timex.h"
+#include "periph/gpio.h"
+
+#include "dht.h"
+
+#define ENABLE_DEBUG    (0)
+#include "debug.h"
+
+/***********************************************************************
+ * internal API declaration
+ **********************************************************************/
+
+static void dht_read_data(gpio_t dev, uint32_t *data, uint8_t *checksum);
+static int dht_test_checksum(uint32_t data, uint8_t checksum);
+void dht_parse_11(dht_data_t *data, float *outhum, float *outtemp);
+void dht_parse_22(dht_data_t *data, float *outhum, float *outtemp);
+
+/***********************************************************************
+ * internal API implementation
+ **********************************************************************/
+
+void dht_parse_11(dht_data_t *data, float *outhum, float *outtemp)
+{
+    *outhum = data->humidity >> 8;
+    *outtemp = data->temperature >> 8;
+}
+
+void dht_parse_22(dht_data_t *data, float *outhum, float *outtemp)
+{
+    *outhum = data->humidity / 10;
+
+    /* the highest bit indicates a negative value */
+    if (data->temperature & 0x8000) {
+        *outtemp = (data->temperature & 0x7FFF) / -10;
+    }
+    else {
+        *outtemp = data->temperature / 10;
+    }
+}
+
+static int dht_test_checksum(uint32_t data, uint8_t checksum)
+{
+    uint8_t sum;
+    sum  = (data >>  0) & 0x000000FF;
+    sum += (data >>  8) & 0x000000FF;
+    sum += (data >> 16) & 0x000000FF;
+    sum += (data >> 24) & 0x000000FF;
+
+    return ((checksum == sum) && (checksum != 0));
+}
+
+static void dht_read_data(gpio_t dev, uint32_t *data, uint8_t *checksum)
+{
+    /* send init signal to device */
+    gpio_clear(dev);
+    hwtimer_wait(HWTIMER_TICKS(20 * MS_IN_USEC));
+    gpio_set(dev);
+    hwtimer_wait(HWTIMER_TICKS(40));
+
+    /* sync on device */
+    gpio_init_in(dev, GPIO_PULLUP);
+    while (!gpio_read(dev)) ;
+    while (gpio_read(dev)) ;
+
+    /*
+     * data is read in sequentially, highest bit first:
+     *  40 .. 24  23   ..   8  7  ..  0
+     * [humidity][temperature][checksum]
+     */
+
+    /* read all the bits */
+    uint64_t les_bits = 0x00000000000000;
+    for (int c = 0; c < 40; c++) {
+        les_bits <<= 1; /* this is a nop in the first iteration, but
+                           we must not shift the last bit */
+        /* wait for start of bit */
+        while (!gpio_read(dev)) ;
+        unsigned long start = hwtimer_now();
+        /* wait for end of bit */
+        while (gpio_read(dev)) ;
+        /* calculate bit length (long 1, short 0) */
+        unsigned long stop = hwtimer_now();
+        /* compensate for overflow if needed */
+        if (stop < start) {
+            stop = HWTIMER_MAXTICKS - stop;
+            start = 0;
+        }
+        if ((stop - start) > 40) {
+            /* read 1, set bit */
+            les_bits |= 0x0000000000000001;
+        }
+        else {
+            /* read 0, don't set bit */
+        }
+    }
+
+    *checksum = les_bits & 0x00000000000000FF;
+    *data = (les_bits >> 8) & 0x00000000FFFFFFFF;
+
+    gpio_init_out(dev, GPIO_PULLUP);
+    gpio_set(dev);
+}
+
+/***********************************************************************
+ * public API implementation
+ **********************************************************************/
+
+int dht_init(dht_t *dev, dht_type_t type, gpio_t gpio)
+{
+    DEBUG("dht_init\n");
+
+    dev->gpio = gpio;
+    dev->type = type;
+
+    if (gpio_init_out(gpio, GPIO_PULLUP) == -1) {
+        return -1;
+    }
+    gpio_set(gpio);
+
+    hwtimer_wait(HWTIMER_TICKS(2000 * MS_IN_USEC));
+
+    DEBUG("dht_init: success\n");
+    return 0;
+}
+
+
+int dht_read_raw(dht_t *dev, dht_data_t *outdata)
+{
+    uint32_t data;
+    uint8_t checksum;
+
+    /* read raw data */
+    dht_read_data(dev->gpio, &data, &checksum);
+
+    /* check checksum */
+    int ret = dht_test_checksum(data, checksum);
+    if (!ret) {
+        DEBUG("checksum fail\n");
+    }
+
+    outdata->humidity = data >> 16;
+    outdata->temperature = data & 0x0000FFFF;
+
+    return (ret - 1); /* take that logic! */
+}
+
+void dht_parse(dht_t *dev, dht_data_t *data, float *outrelhum, float *outtemp)
+{
+    switch (dev->type) {
+        case (DHT11):
+            dht_parse_11(data, outrelhum, outtemp);
+            break;
+
+        case DHT22:
+            dht_parse_22(data, outrelhum, outtemp);
+            break;
+
+        default:
+            DEBUG("unknown DHT type\n");
+    }
+}
+
+int dht_read(dht_t *dev, float *outrelhum, float *outtemp)
+{
+    /* read data, fail on error */
+    dht_data_t data;
+    if (dht_read_raw(dev, &data) == -1) {
+        return -1;
+    }
+
+    dht_parse(dev, &data, outrelhum, outtemp);
+    return 0;
+}

drivers/include/dht.h

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2015 Ludwig Ortmann, Christian Mehlis
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup    driver_dht DHT Family of Humidity and Temperature Sensors
+ * @ingroup     drivers
+ * @brief       Device driver for the DHT Family of humidity
+ *              and temperature sensors
+ *
+ * @{
+ *
+ * @file
+ * @brief       Device driver interface for the DHT family of humidity
+ *              and temperature sensors
+ *
+ * @author      Ludwig Ortmann <ludwig.ortmann@fu-berlin.de
+ * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
+ */
+
+#ifndef DHT_H
+#define DHT_H
+
+#include <stdint.h>
+
+#include "periph/gpio.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief data type for storing DHT sensor readings
+ */
+typedef struct {
+    uint16_t humidity;      /**< relative deca-humidity */
+    uint16_t temperature;   /**< temperature in deca-Celsius */
+} dht_data_t;
+
+/**
+ * @brief device type of the DHT device
+ */
+typedef enum {
+    DHT11,                  /**< DHT11 device identifier */
+    DHT22                   /**< DHT22 device identifier */
+} dht_type_t;
+
+/**
+ * @brief device descriptor for DHT sensor devices
+ */
+typedef struct {
+    gpio_t gpio;            /**< GPIO pin of the device's data pin */
+    dht_type_t type;        /**< type of the DHT device */
+} dht_t;
+
+/**
+ * @brief initialize a new DHT device
+ *
+ * @param[in] dev       device descriptor of a DHT device
+ * @param[in] type      type of the DHT device
+ * @param[in] gpio      GPIO pin the device's data pin is connected to
+ *
+ * @return              0 on success
+ * @return              -1 on error
+ */
+int dht_init(dht_t *dev, dht_type_t type, gpio_t gpio);
+
+ /**
+ * @brief   read sensor data from device
+ *
+ * @param[in]  dev      device descriptor of a DHT device
+ * @param[out] relhum   pointer to relative humidity in g/m^3
+ * @param[out] temp     pointer to temperature in degrees Celsius
+ *
+ * @return              0 on success
+ * @return              -1 on error
+ */
+int dht_read(dht_t *dev, float *relhum, float *temp);
+
+ /**
+ * @brief   read sensor data from device
+ *
+ * @note    When reading fails and the function indicates an error,
+ *          data will contain garbage.
+ *
+ * @param[in] dev       device descriptor of a DHT device
+ * @param[in] data      pointer to DHT data object
+ *
+ * @return              0 on success
+ * @return              -1 on checksum error
+ */
+int dht_read_raw(dht_t *dev, dht_data_t *data);
+
+/**
+ * @brief   parse raw sensor data into relative humidity and Celsius
+ *
+ * @param[in]   dev     device descriptor of a DHT device
+ * @param[in]   data    sensor data
+ * @param[out]  relhum  pointer to relative humidity in g/m^3
+ * @param[out]  temp    pointer to temperature in degrees Celsius
+ */
+void dht_parse(dht_t *dev, dht_data_t *data, float *relhum, float *temp);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* DHT_H */
+/** @} */

tests/driver_dht/Makefile

@@ -0,0 +1,27 @@
+APPLICATION = driver_dht
+include ../Makefile.tests_common
+
+FEATURES_REQUIRED = periph_gpio
+
+# define default pin mappings for some boards:
+ifneq (,$(filter stm32f4discovery,$(BOARD)))
+  export DHT_GPIO ?= GPIO_4
+endif
+
+USEMODULE += dht
+
+ifneq (,$(DHT_TYPE))
+  CFLAGS += -DDHT_TYPE=$(DHT_TYPE)
+else
+  # set random default
+  CFLAGS += -DDHT_TYPE=DHT11
+endif
+
+ifneq (,$(DHT_GPIO))
+  CFLAGS += -DDHT_GPIO=$(DHT_GPIO)
+else
+  # set random default
+  CFLAGS += -DDHT_GPIO=GPIO_0
+endif
+
+include $(RIOTBASE)/Makefile.include

tests/driver_dht/main.c

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2015 Ludwig Ortmann, Christian Mehlis
+ *
+ * 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 tests
+ * @{
+ *
+ * @file
+ * @brief       Test application for the dht humidity and temperature sensor driver
+ *
+ * @author      Ludwig Ortmann <ludwig.ortmann@fu-berlin.de>
+ * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
+ *
+ * @}
+ */
+
+#ifndef DHT_TYPE
+#error "DHT_TYPE not defined"
+#endif
+
+#ifndef DHT_GPIO
+#error "DHT_GPIO not defined"
+#endif
+
+#include <stdio.h>
+
+#include "hwtimer.h"
+#include "timex.h"
+
+#include "dht.h"
+
+int main(void)
+{
+    dht_t dev;
+
+    puts("DHT temperature and humidity sensor test application\n");
+
+    printf("Initializing DHT sensor at GPIO_%i... ", DHT_GPIO);
+    if (dht_init(&dev, DHT_TYPE, DHT_GPIO) == 0) {
+        puts("[OK]\n");
+    }
+    else {
+        puts("[Failed]");
+        return 1;
+    }
+
+    dht_data_t data;
+    float temp, hum;
+    while (1) {
+
+        if (dht_read_raw(&dev, &data) == -1) {
+            puts("error reading data");
+        }
+        dht_parse(&dev, &data, &hum, &temp);
+        printf("raw relative humidity: %i\nraw temperature: %i C\n", data.humidity, data.temperature);
+        printf("relative humidity: %i\ntemperature: %i C\n", (int) hum, (int) temp);
+        hwtimer_wait(HWTIMER_TICKS(2000 * MS_IN_USEC));
+    }
+
+    return 0;
+}