0.1.1 DHT20

libraries/DHT20/DHT20.cpp

@@ -1,16 +1,19 @@
 //
 //    FILE: DHT20.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
+// VERSION: 0.1.1
 // PURPOSE: Arduino library for DHT20 I2C temperature and humidity sensor.
 //
 // HISTORY:
-//  0.1.0   2022-01-11  initial version (based upon DHT20)
-
+//  0.1.0   2022-01-11  initial version (based upon DHT20 datasheet)
+//  0.1.1   2022-09-10  add hardware schema to readme.md.
+//                      fix async interface (first version)
 
 
 #include "DHT20.h"
 
+#define DHT20_ACQUISITION_TIME      85
+
 const uint8_t DHT20_ADDRESS = 0x38;
 
 
@@ -57,24 +60,25 @@ bool DHT20::isConnected()
 }
 
 
-bool DHT20::readyData()
-{
-  return ((millis() - _lastRequest) > 85);
-}
-
-
 int DHT20::read()
 {
   //  READ SENSOR ==> uses the async interface!
+  //  check lastRead!
   int status = _requestData();
   if (status < 0) return status;
-  while (!readyData())
+  while ((millis() - _lastRequest) <= DHT20_ACQUISITION_TIME)
   {
     yield();
     delay(1);
   }
   _readData();
 
+  return convert();
+}
+
+
+int DHT20::convert()
+{
   //  CONVERT AND STORE
   _status      = _bits[0];
   uint32_t tmp = _bits[1];

libraries/DHT20/DHT20.h

@@ -3,16 +3,25 @@
 //    FILE: DHT20.h
 //  AUTHOR: Rob Tillaart
 // PURPOSE: Arduino library for DHT20 I2C temperature and humidity sensor.
-// VERSION: 0.1.0
+// VERSION: 0.1.1
 // HISTORY: See DHT20.cpp
 //     URL: https://github.com/RobTillaart/DHT20
 //
 
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
+
 
 #include "Arduino.h"
 #include "Wire.h"
 
-#define DHT20_LIB_VERSION                    (F("0.1.0"))
+#define DHT20_LIB_VERSION                    (F("0.1.1"))
 
 #define DHT20_OK                             0
 #define DHT20_ERROR_CHECKSUM                -10
@@ -20,6 +29,9 @@
 #define DHT20_MISSING_BYTES                 -12
 
 
+#define DHT20_ACQUISITION_TIME               85
+
+
 class DHT20
 {
 public:
@@ -33,9 +45,8 @@ public:
 
   //  ASYNCHRONUOUS CALL
   int      requestData() { return _requestData(); };
-  bool     readyData();
   int      readData()    { return _readData(); };
-
+  int      convert();
 
   //  SYNCHRONUOUS CALL
   int      read();

libraries/DHT20/README.md

@@ -24,6 +24,25 @@ The **read()** call of this sensor is blocking for 80+ milliseconds (datasheet 7
 so the library also has a asynchronous interface. See below.
 
 
+## Connection
+
+Always check datasheet 
+
+Front view
+```
+          +--------------+
+  VDD ----| 1            |
+  SDA ----| 2    DHT20   |
+  GND ----| 3            |
+  SCL ----| 4            |
+          +--------------+
+```
+
+## Tested
+
+Examples verified to work with Arduino UNO and ESP32.
+
+
 ## Interface
 
 
@@ -53,14 +72,33 @@ It returns the status of the read which should be 0.
 
 ### Asynchronous interface
 
-The async interface allows one to continue processing after a **requestData()** has been made.
-One can check **readyData()** and if it returns true, enough time has 
-passed to make the measurement and the sensor can be read with **readData()**.
+Note the async interface is not 100% functional yet. 
+Expect functional complete in 0.2.0.
+
+There are two timings that need to be considdered, 
+- time between requests = 1000 ms
+- time between request and data ready.
+
+The async interface allows one to continue processing whatever after a **requestData()** has been made. Note that there should be at least **1000 milliseconds** between subsequent requests.
+
+After **DHT20_ACQUISITION_TIME == 85 ms** enough time after the request has 
+passed to read the data of the measurement. So the sensor can be read with **readData()**.
+
+To interpret the read bits to temperature, humidity and status one needs to call **convert()** as last step.
+
 
 - **int requestData()** signals the sensor to make a new measurement.
-- **bool readyData()** returns true if 85 milliseconds have passed since the last **requestData()** call. 
-The time of 85 ms is hard coded.
+Note there must be at least 1000 milliseconds between requests!
 - **int readData()** does the actual reading of the data.
+- **int convert()** converts the read bits to temperature and humidity.
+
+See the example **DHT20_async.ino**
+
+In the .h file there is a line
+```cpp
+#define DHT20_ACQUISITION_TIME      85
+```
+This can be used to optimize performance a bit. Use with care.
 
 
 ### Miscellaneous
@@ -89,23 +127,30 @@ See examples
 
 ## Future
 
+#### must
+
 - update documentation
+- improve the code
+  - check return codes etc.
   - add missing error codes
-  - describe async interface
+  - **read()** should check lastRead() and return ERROR_LASTREAD
+
+#### should
+
 - test more in detail
   - test on ESP32
+- add examples
+  - asynchronous
+
+#### could
+
 - improve unit tests.
-- improve the code (check return codes etc.)
 - investigate 
   - status register bits 
   - sensor calibration (website aosong?)
 - check for optimizations.
   - mainly for asynchronous
-  - test at different I2C speeds 400 KHz should be possible.
   - 85 ms wait time?
-- add examples
-  - asynchronous
-  - 
 
 
 #### won't

libraries/DHT20/examples/DHT20/DHT20.ino

@@ -4,15 +4,25 @@
 // PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
 //
 
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
+
 
 #include "DHT20.h"
 
 DHT20 DHT;
 
+uint8_t count = 0;
 
 void setup()
 {
-  DHT.begin();
+  DHT.begin();    //  ESP32 default pins 21 22
 
   Wire.setClock(400000);
 
@@ -24,7 +34,7 @@ void setup()
 
   delay(2000);
 
-  Serial.println("Type,\tStatus,\tHumidity (%),\tTemperature (C)");
+
 }
 
 
@@ -36,31 +46,41 @@ void loop()
     uint32_t start = micros();
     int status = DHT.read();
     uint32_t stop = micros();
+
+    if ((count % 10) == 0)
+    {
+      count = 0;
+      Serial.println();
+      Serial.println("Type\tHumidity (%)\tTemp (°C)\tTime (µs)\tStatus");
+    }
+    count++;
+
+    Serial.print("DHT20 \t");
+    // DISPLAY DATA, sensor has only one decimal.
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print("\t\t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.print("\t\t");
+    Serial.print(stop - start);
+    Serial.print("\t\t");
     switch (status)
     {
       case DHT20_OK:
-      Serial.print("OK,\t");
+        Serial.print("OK");
         break;
       case DHT20_ERROR_CHECKSUM:
-      Serial.print("Checksum error,\t");
+        Serial.print("Checksum error");
         break;
       case DHT20_ERROR_CONNECT:
-      Serial.print("Connect error,\t");
+        Serial.print("Connect error");
         break;
       case DHT20_MISSING_BYTES:
-      Serial.print("Missing bytes,\t");
+        Serial.print("Missing bytes");
         break;
       default:
-      Serial.print("Unknown error,\t");
+        Serial.print("Unknown error");
         break;
     }
-    // DISPLAY DATA, sensor has only one decimal.
-    Serial.print("DHT20, \t");
-    Serial.print(DHT.getHumidity(), 1);
-    Serial.print(",\t");
-    Serial.print(DHT.getTemperature(), 1);
-    Serial.print(",\t");
-    Serial.print(stop - start);
     Serial.print("\n");
   }
 }

libraries/DHT20/examples/DHT20_I2C_speed/DHT20_I2C_speed.ino

@@ -0,0 +1,58 @@
+//
+//    FILE: DHT20_I2C_speed.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
+//
+
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
+
+//  NOTE datasheet states 400 KHz as maximum
+
+#include "DHT20.h"
+
+DHT20 DHT;
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("DHT20 LIBRARY VERSION: ");
+  Serial.println(DHT20_LIB_VERSION);
+  Serial.println();
+
+  Serial.println("\nNOTE: datasheet states 400 KHz as maximum.\n");
+
+  DHT.begin();  //  ESP32 default pins 21, 22
+  delay(2000);
+
+  for (uint32_t speed = 50000; speed < 850000; speed += 50000)
+  {
+    Wire.setClock(speed);
+    Serial.print(speed);
+    Serial.print("\t");
+    Serial.print(DHT.read());  // status
+    Serial.print("\t");
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print("\t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.println();
+    delay(1000);
+  }
+
+  Serial.println("\ndone...");
+}
+
+
+void loop()
+{
+}
+
+
+// -- END OF FILE --

libraries/DHT20/examples/DHT20_async/DHT20_async.ino

@@ -0,0 +1,68 @@
+//
+//    FILE: DHT20_async.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
+//
+
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
+
+
+#include "DHT20.h"
+
+DHT20 DHT;
+
+uint32_t counter = 0;
+
+void setup()
+{
+  DHT.begin();  //  ESP32 default 21, 22
+
+  Wire.setClock(400000);
+
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("DHT20 LIBRARY VERSION: ");
+  Serial.println(DHT20_LIB_VERSION);
+  Serial.println();
+
+  delay(2000);
+
+  //  start with initial request
+  Serial.println(DHT.requestData());
+
+}
+
+
+void loop()
+{
+  uint32_t now = millis();
+
+  if (now - DHT.lastRead() > 1000)
+  {
+    DHT.readData();
+    DHT.convert();
+
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print(" %RH \t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.print(" °C\t");
+    Serial.print(counter);
+    Serial.print("\n");
+    //  new request
+    counter = 0;
+    DHT.requestData();
+  }
+
+  //  other code here
+  counter++;  //  dummy counter to show async behaviour
+}
+
+
+// -- END OF FILE --

libraries/DHT20/examples/DHT20_plotter/DHT20_plotter.ino

@@ -4,6 +4,14 @@
 // PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
 //
 
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
 
 #include "DHT20.h"
 
@@ -12,7 +20,7 @@ DHT20 DHT(&Wire);
 
 void setup()
 {
-  DHT.begin();
+  DHT.begin();  //  ESP32 default pins 21 22
   Serial.begin(115200);
   Serial.println("Humidity, Temperature");
 }

libraries/DHT20/examples/DHT20_test_esp/DHT20_test_esp.ino

@@ -4,7 +4,14 @@
 // PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
 //
 
-// TODO
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
 
 #include "DHT20.h"
 
@@ -54,6 +61,7 @@ void loop()
     Serial.print("Unknown error,\t");
     break;
   }
+
   //  DISPLAY DATA, sensor has only one decimal.
   Serial.print(DHT.getHumidity(), 1);
   Serial.print(",\t");

libraries/DHT20/keywords.txt

@@ -8,8 +8,8 @@ begin	KEYWORD2
 isConnected	KEYWORD2
 
 requestData	KEYWORD2
-readyData	KEYWORD2
 readData	KEYWORD2
+convert	KEYWORD2
 
 read	KEYWORD2
 getHumidity	KEYWORD2

libraries/DHT20/library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/DHT20.git"
   },
-  "version": "0.1.0",
+  "version": "0.1.1",
   "license": "MIT",
   "frameworks": "arduino",
   "platforms": "*",

libraries/DHT20/library.properties

@@ -1,5 +1,5 @@
 name=DHT20
-version=0.1.0
+version=0.1.1
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for I2C DHT20 temperature and humidity sensor.