Merge pull request #16934 from wosym/dht11fix

drivers/dht: correct interpreting raw values

CODEOWNERS

@@ -82,6 +82,7 @@
 /drivers/ccs811/                            @gschorcht
 /drivers/enc28j60/                          @haukepetersen
 /drivers/dcf77/                             @daexel
+/drivers/dht/                               @wosym
 /drivers/dose/                              @jue89
 /drivers/ds18/                              @leandrolanzieri
 /drivers/itg320x/                           @gschorcht
@@ -141,6 +142,7 @@
 /tests/                                     @smlng @leandrolanzieri @aabadie @MichelRottleuthner @fjmolinas
 /tests/candev/                              @wosym
 /tests/driver_bq2429x/                      @jeandudey
+/tests/driver_dht/                          @wosym
 /tests/gnrc*                                @miri64
 /tests/lwip*                                @miri64
 /tests/slip/                                @miri64

drivers/dht/dht.c

@@ -13,7 +13,7 @@
  * @{
  *
  * @file
- * @brief       Device driver implementation for the DHT 11 and 22
+ * @brief       Device driver implementation for the DHT11, 21 and 22
  *              temperature and humidity sensor
  *
  * @author      Ludwig Knüpfer <ludwig.knuepfer@fu-berlin.de>
@@ -75,12 +75,12 @@ static inline int _wait_for_level(gpio_t pin, bool expect, unsigned timeout)
     return (timeout > 0) ? 0 : -1;
 }
 
-static int _read(uint16_t *dest, gpio_t pin, int bits)
+static int _read(uint8_t *dest, gpio_t pin)
 {
-    DEBUG("read\n");
+    DEBUG("[dht] read\n");
     uint16_t res = 0;
 
-    for (int i = 0; i < bits; i++) {
+    for (int i = 0; i < 8; i++) {
         uint32_t start, end;
         res <<= 1;
         /* measure the length between the next rising and falling flanks (the
@@ -107,11 +107,10 @@ static int _read(uint16_t *dest, gpio_t pin, int bits)
 
 int dht_init(dht_t *dev, const dht_params_t *params)
 {
-    DEBUG("dht_init\n");
+    DEBUG("[dht] dht_init\n");
 
     /* check parameters and configuration */
     assert(dev && params);
-    assert((params->type == DHT11) || (params->type == DHT22) || (params->type == DHT21));
 
     memset(dev, 0, sizeof(dht_t));
     dev->params = *params;
@@ -120,14 +119,14 @@ int dht_init(dht_t *dev, const dht_params_t *params)
 
     xtimer_msleep(2000);
 
-    DEBUG("dht_init: success\n");
+    DEBUG("[dht] dht_init: success\n");
     return DHT_OK;
 }
 
 int dht_read(dht_t *dev, int16_t *temp, int16_t *hum)
 {
-    uint16_t csum;
+    uint8_t csum;
-    uint16_t raw_hum, raw_temp;
+    uint8_t raw_temp_i, raw_temp_d, raw_hum_i, raw_hum_d;
 
     assert(dev);
 
@@ -158,17 +157,24 @@ int dht_read(dht_t *dev, int16_t *temp, int16_t *hum)
          */
 
         /* read the humidity, temperature, and checksum bits */
-        if (_read(&raw_hum, dev->params.pin, 16)) {
+        if (_read(&raw_hum_i, dev->params.pin)) {
+            _reset(dev);
+            return DHT_TIMEOUT;
+        }
+        if (_read(&raw_hum_d, dev->params.pin)) {
+            _reset(dev);
+            return DHT_TIMEOUT;
+        }
+        if (_read(&raw_temp_i, dev->params.pin)) {
+            _reset(dev);
+            return DHT_TIMEOUT;
+        }
+        if (_read(&raw_temp_d, dev->params.pin)) {
             _reset(dev);
             return DHT_TIMEOUT;
         }
 
-        if (_read(&raw_temp, dev->params.pin, 16)) {
+        if (_read(&csum, dev->params.pin)) {
-            _reset(dev);
-            return DHT_TIMEOUT;
-        }
-
-        if (_read(&csum, dev->params.pin, 8)) {
             _reset(dev);
             return DHT_TIMEOUT;
         }
@@ -178,33 +184,23 @@ int dht_read(dht_t *dev, int16_t *temp, int16_t *hum)
         _reset(dev);
 
         /* validate the checksum */
-        uint8_t sum = (raw_temp >> 8) + (raw_temp & 0xff) + (raw_hum >> 8)
+        uint8_t sum = (raw_temp_i) + (raw_temp_d) + (raw_hum_i) + (raw_hum_d);
-                    + (raw_hum & 0xff);
         if (sum != csum) {
-            DEBUG("error: checksum doesn't match\n");
+            DEBUG("[dht] error: checksum doesn't match\n");
             return DHT_NOCSUM;
         }
 
         /* parse the RAW values */
-        DEBUG("RAW values: temp: %7i hum: %7i\n", (int)raw_temp, (int)raw_hum);
+        DEBUG("[dht] RAW values: temp: %2i.%i hum: %2i.%i\n", (int)raw_temp_i,
-        switch (dev->params.type) {
+            (int)raw_temp_d, (int)raw_hum_i, (int)raw_hum_d);
-            case DHT11:
+
-                dev->last_val.temperature = (int16_t)((raw_temp >> 8) * 10);
+        dev->last_val.humidity = raw_hum_i * 10 + raw_hum_d;
-                dev->last_val.humidity = (int16_t)((raw_hum >> 8) * 10);
+        /* MSB set means negative temperature on DHT22. Will always be 0 on DHT11 */
-                break;
+        if (raw_temp_i & 0x80) {
-            /* DHT21 == DHT22 (same value in enum), so both are handled here */
+            dev->last_val.temperature = -((raw_temp_i & ~0x80) * 10 + raw_temp_d);
-            case DHT22:
-                dev->last_val.humidity = (int16_t)raw_hum;
-                /* if the high-bit is set, the value is negative */
-                if (raw_temp & 0x8000) {
-                    dev->last_val.temperature = (int16_t)((raw_temp & ~0x8000) * -1);
         }
         else {
-                    dev->last_val.temperature = (int16_t)raw_temp;
+            dev->last_val.temperature = raw_temp_i * 10 + raw_temp_d;
-                }
-                break;
-            default:
-                return DHT_NODEV;      /* this should never be reached */
         }
 
         /* update time of last measurement */

drivers/dht/include/dht_params.h

@@ -34,15 +34,11 @@ extern "C" {
 #ifndef DHT_PARAM_PIN
 #define DHT_PARAM_PIN               (GPIO_PIN(0, 0))
 #endif
-#ifndef DHT_PARAM_TYPE
-#define DHT_PARAM_TYPE              (DHT11)
-#endif
 #ifndef DHT_PARAM_PULL
 #define DHT_PARAM_PULL              (GPIO_IN_PU)
 #endif
 #ifndef DHT_PARAMS
 #define DHT_PARAMS                  { .pin     = DHT_PARAM_PIN,  \
-                                      .type    = DHT_PARAM_TYPE, \
                                       .in_mode = DHT_PARAM_PULL }
 #endif
 #ifndef DHT_SAULINFO

drivers/include/dht.h

@@ -46,35 +46,23 @@ enum {
     DHT_OK      =  0,       /**< all good */
     DHT_NOCSUM  = -1,       /**< checksum error */
     DHT_TIMEOUT = -2,       /**< communication timed out */
-    DHT_NODEV   = -3        /**< device type not defined */
 };
 
 /**
  * @brief   Data type for storing DHT sensor readings
  */
 typedef struct {
-    uint16_t humidity;      /**< relative deca-humidity */
+    uint16_t humidity;      /**< relative percent */
-    uint16_t temperature;   /**< temperature in deca-Celsius */
+    uint16_t temperature;   /**< temperature in deci-Celsius */
 } dht_data_t;
 
-/**
- * @brief   Device type of the DHT device
- */
-typedef enum {
-    DHT11,                  /**< DHT11 device identifier */
-    DHT22,                  /**< DHT22 device identifier */
-    DHT21 = DHT22           /**< DHT21 device identifier */
-} dht_type_t;
-
 /**
  * @brief   Configuration parameters for DHT devices
  */
 typedef struct {
     gpio_t pin;             /**< GPIO pin of the device's data pin */
-    dht_type_t type;        /**< type of the DHT device */
     gpio_mode_t in_mode;    /**< input pin configuration, with or without pull
                              *   resistor */
-
 } dht_params_t;
 
 /**
@@ -110,7 +98,6 @@ int dht_init(dht_t *dev, const dht_params_t *params);
  * @retval DHT_OK       Success
  * @retval DHT_NOCSUM   Checksum error
  * @retval DHT_TIMEOUT  Reading data timed out (check wires!)
- * @retval DHT_NODEV    Unsupported device type specified
  */
 int dht_read(dht_t *dev, int16_t *temp, int16_t *hum);
 

tests/driver_dht/Makefile

@@ -1,7 +1,6 @@
 include ../Makefile.tests_common
 
 USEMODULE += dht
-USEMODULE += fmt
 USEMODULE += xtimer
 
 include $(RIOTBASE)/Makefile.include

tests/driver_dht/app.config.test

@@ -1,5 +1,4 @@
 # this file enables modules defined in Kconfig. Do not use this file for
 # application configuration. This is only needed during migration.
 CONFIG_MODULE_DHT=y
-CONFIG_MODULE_FMT=y
 CONFIG_MODULE_XTIMER=y

tests/driver_dht/main.c

@@ -35,8 +35,6 @@ int main(void)
 {
     dht_t dev;
     int16_t temp, hum;
-    char temp_s[10];
-    char hum_s[10];
 
     puts("DHT temperature and humidity sensor test application\n");
 
@@ -57,13 +55,8 @@ int main(void)
             continue;
         }
 
-        size_t n = fmt_s16_dfp(temp_s, temp, -1);
+        printf("DHT values - temp: %d.%d°C - relative humidity: %d.%d%%\n",
-        temp_s[n] = '\0';
+               temp/10, temp%10, hum/10, hum%10);
-        n = fmt_s16_dfp(hum_s, hum, -1);
-        hum_s[n] = '\0';
-
-        printf("DHT values - temp: %s°C - relative humidity: %s%%\n",
-                temp_s, hum_s);
 
         xtimer_usleep(DELAY);
     }