Diff: Handlers/GroveDht22.h

Revision:

0:2df78a4443cd

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Handlers/GroveDht22.h	Sun Apr 10 15:47:33 2016 +1000
@@ -0,0 +1,81 @@
+#ifndef __GROVE_DHT_22_H__
+#define __GROVE_DHT_22_H__
+
+#include "DHT.h"
+#include "mbed.h"
+#include "AbstractHandler.h"
+
+class MeasurementHandler;
+
+/*!
+ * \brief The Dht22Result struct is the information read from a Dht22 Grove sensor
+ */
+struct Dht22Result {
+    time_t resultTime;      ///< timestamp of when the result was returned from the Dht22
+    float  lastCelcius;     ///< Temperature result (degC)
+    float  lastHumidity;    ///< Humidity result
+    float  lastDewpoint;    ///< Dewpoint result
+};
+
+/*!
+ * \brief The GroveDht22 class handles the interface to the DHT22 humidity and temperature sensor.
+ *
+ * The state machine checks for errors and retries and will power cycle the sensor if there are
+ * GROVE_NUM_RETRIES number of retries.
+
+ * The state machine also ensures that at least two seconds is left between readings.
+
+ * At any time the parent class can access the last good readings, or the last error.
+
+ * The newInfo flag exists so that the parent can decide to only notify (print to terminal or otherwise) when there
+ * is new information available. Calling the newInfo getter will clear the newInfo flag.
+ */
+class GroveDht22 : public AbstractHandler
+{
+public:
+    GroveDht22(MeasurementHandler *_measure, MyTimers * _timer);
+    ~GroveDht22();
+
+    void run();
+
+    void setRequest(int request, void *data = 0);
+
+    // getters
+    float  lastCelcius()  { return _lastCelcius; }
+    float  lastHumidity() { return _lastHumidity; }
+    float  lastDewPoint() { return _lastDewpoint; }
+    eError lastError()    { return _lastError; }
+    unsigned char newInfo();
+
+private:
+    // state machine
+    typedef enum {
+        dht_StartTurnOff,       ///< Begin by ensuring the sensor is switched off
+        dht_StartTurnOffWait,   ///< Allow it to power down completely
+        dht_StartTurnOn,        ///< Turn the sensor on
+        dht_StartTurnOnWait,    ///< Allow sensor to settle after powering on
+        dht_TakeMeasurement,    ///< Take a measurement, check if valid, update measurment vars, set newInfo
+        dht_WaitMeasurement     ///< Wait for 2 seconds between measurements
+    } mode_t;
+
+    mode_t mode;            ///< The current state in the state machine
+
+    float _lastCelcius;     ///< Last temperature reading from the Dht22 sensor
+    float _lastHumidity;    ///< Last humidity reading from the Dht22 sensor
+    float _lastDewpoint;    ///< Last dewpoint calculation from last temp, humidity vales
+    unsigned char _newInfo; ///< This flag indicates there is new information (an error, or a measurement)
+    int _retries;           ///< Number of bad readings from the Dht22 sensor
+    eError _lastError;      ///< The last error, or lack thereof
+
+    /*!
+     * \brief powerOn powers the Dht22 on or off, by toggling the enable pin
+     * \param ON true to power on, false to power off
+     */
+    void powerOn(unsigned char ON);
+
+    MeasurementHandler *m_measure;  ///< Reference to send measurement results and errors to for handling
+
+    DHT *m_sensor;                  ///< Interface to hardware DHT sensor
+};
+
+#endif // __GROVE_DHT_22_H__