Revision 13:11d0770eb603, committed 2021-09-15

Comitter:

ajp109

Date:

Wed Sep 15 14:47:06 2021 +0000

Parent:

12:af1eadec17e5

Commit message:

Interface changes to remove the need for separate readData() calls

Changed in this revision

--- a/DHT11.cpp	Mon May 31 07:02:00 2021 +0000
+++ b/DHT11.cpp	Wed Sep 15 14:47:06 2021 +0000
@@ -1,4 +1,5 @@
 /* Copyright (c) 2014 Shigenori Inoue, MIT License
+ * Modified by Andy Pomfret 2021
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
  * and associated documentation files (the "Software"), to deal in the Software without restriction, 
@@ -25,7 +26,7 @@
     io_irq.fall(callback(this, &DHT11::neg_edge));
     io_irq.disable_irq();
     t.start();
-    first_time = true;
+    readNewData();
 }
 
 // Destructor
@@ -39,10 +40,10 @@
 int DHT11::readData(void)
 {
     // Checking the measurement frequency
-    if (chrono::duration_cast<chrono::milliseconds>(t.elapsed_time()).count() < 2000 && first_time == false) {
-        t.reset();
-        return READ_TOO_OFTEN;
-    }
+//    if (chrono::duration_cast<chrono::milliseconds>(t.elapsed_time()).count() < 2000) {
+//        t.reset();
+//        return READ_TOO_OFTEN;
+//    }
     
     // Initialize
     init();
@@ -57,8 +58,7 @@
     t.reset();
     io.output();
     io = 0;
-    do {
-    } while (chrono::duration_cast<chrono::milliseconds>(t.elapsed_time()).count() < 20 + t_tol_start);
+    thread_sleep_for(10 + t_tol_start);
     io.input();
     io = 1;
     
@@ -72,7 +72,7 @@
         }
     } while (io == 1);
 
-    // Wainting for the start of the ready signal
+    // Waiting for the start of the ready signal
     t.reset();
     do {
         if (t.elapsed_time().count() > 100) {
@@ -81,7 +81,7 @@
         }
     } while (io == 0);
 
-    // Wainting for the end of the ready signal
+    // Waiting for the end of the ready signal
     t.reset();
     do {
         if (t.elapsed_time().count() > 100) {
@@ -91,7 +91,7 @@
     } while (io == 1);
 
     // Starting the pulse width sensing
-    // by the use of interruptions
+    // by the use of interrupts
     io_irq.enable_irq();
 
     do {
@@ -104,30 +104,39 @@
     } while (eod == false);
 
     // Calculating the check sum
-    chksum = ((data & 0xff00000000) >> 32)
-             + ((data & 0x00ff000000) >> 24)
-             + ((data & 0x0000ff0000) >> 16)
-             + ((data & 0x000000ff00) >> 8);
+    chksum = (data >> 32)
+             + (data >> 24)
+             + (data >> 16)
+             + (data >> 8);
 
-    if (chksum != (data & 0x00000000ff)) {
+    if ((chksum & 0xff) != (data & 0x00000000ff)) {
         t.reset();
         return CHKSUM_ERR;
     } else {
         t.reset();
-        first_time = false;
         return OK;
     }
 }
 
+void DHT11::readNewData(void) {
+    do; while (readData() != OK);
+}
+
 // Extracting humidity data from the received data
 int DHT11::readHumidity(void)
 {
+    if (t.elapsed_time() >= 2000ms) {
+        readNewData();
+    }
     return (data & 0xff00000000) >> 32;
 }
 
 // Extracting temperature data from the received data
 int DHT11::readTemperature(void)
 {
+    if (t.elapsed_time() >= 2000ms) {
+        readNewData();
+    }
     return (data & 0x0000ff0000) >> 16;
 }
 
@@ -145,19 +154,19 @@
 
 void DHT11::pos_edge(void)
 {
-    // Disabling the interruptions
+    // Disabling the interrupts
     io_irq.disable_irq();
 
     // Initializing the Timer
     t.reset();
 
-    // Enabling the interruptions
+    // Enabling the interrupts
     io_irq.enable_irq();
 }
 
 void DHT11::neg_edge(void)
 {
-    // Disabling the interruptions
+    // Disabling the interrupts
     io_irq.disable_irq();
 
     // Reading the positive pulse width

--- a/DHT11.h	Mon May 31 07:02:00 2021 +0000
+++ b/DHT11.h	Wed Sep 15 14:47:06 2021 +0000
@@ -29,14 +29,7 @@
  *
  * main()
  * {
- *     int s;
- *     s = d.readData();
- *     if (s != DHT11::OK) {
- *         printf("Error!\r\n");
- *     }
- *     else {
- *         printf("T:%d, H:%d\r\n", d.readTemperature(), d.readHumidity());
- *     }
+ *     printf("T:%d, H:%d\r\n", d.readTemperature(), d.readHumidity());
  * }
  * @endcode
  */
@@ -50,7 +43,8 @@
     DHT11(PinName pin);
     ~DHT11();
 
-    /** Reading the data from the DHT11
+    /** Reading the data from the DHT11.  Calling this is not required, but
+     * may be useful for debug.
      * @return Error code
      *     0: OK.
      *     1: Reading the data too often.
@@ -62,15 +56,17 @@
      */
     int readData(void);
 
-    /** Reading the humidity from the data
-     * @return Humidity in %,
-     * regardless of the error from readData()
+    /** Returns the current humidity from the DHT11.  If the existing data record
+     * is older than 2000ms, initiates a read from the device.  Note that errors
+     * may result in infinite attempts to read.
+     * @return Humidity in %
      */
     int readHumidity(void);
 
-    /** Reading the temperature from the data
-     * @return Temperature in Celcius,
-     * regardless of the error from readData()
+    /** Returns the current temperature from the DHT11.  If the existing data record
+     * is older than 2000ms, initiates a read from the device.  Note that errors
+     * may result in infinite attempts to read.
+     * @return Temperature in Celcius
      */
     int readTemperature(void);
 
@@ -91,7 +87,6 @@
     uint32_t t_pulse_us;
     const static int t_tol_start;    
     const static int t_tol_pulse;
-    bool first_time;
     uint64_t data;
     uint32_t chksum;
     uint32_t cnt;
@@ -100,6 +95,7 @@
     void init(void);
     void pos_edge(void);
     void neg_edge(void);
+    void readNewData(void);
 };
 
 #endif
\ No newline at end of file