- fixed issue #123

libraries/SHT31/SHT31.cpp

@@ -1,13 +1,17 @@
 //
 //    FILE: SHT31.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
+// VERSION: 0.1.2
 //    DATE: 2019-02-08
 // PURPOSE: Class for SHT31 I2C temperature humidity sensor
 //          https://www.adafruit.com/product/2857
 //
 // HISTORY:
 // 0.1.0 - 2019-02-08 initial version
+// 0.1.1 - 2019-02-18 add description readStatus(),
+//                    async interface
+// 0.1.2 - 2019-03-05 fix issue #123 - error in humidity
+//                    stable version
 //
 // Released to the public domain
 //
@@ -16,7 +20,8 @@
 
 #define SHT31_READ_STATUS       0xF32D
 #define SHT31_CLEAR_STATUS      0x3041
-#define SHT31_RESET             0x30A2
+#define SHT31_SOFT_RESET        0x30A2
+#define SHT31_HARD_RESET        0x0006
 #define SHT31_MEASUREMENT_FAST  0x2416
 #define SHT31_MEASUREMENT_SLOW  0x2400
 #define SHT31_HEAT_ON           0x306D
@@ -54,15 +59,16 @@ bool SHT31::read(bool fast)
     writeCmd(SHT31_MEASUREMENT_SLOW);
     delay(15);  // table 4 datasheet
   }
+
+  // TODO 5 read bytes would be sufficient when not fast / no CRC...
   readBytes(6, (uint8_t*) &buffer[0]);
 
   if (!fast)
   {
-    // TODO 5 read bytes would be sufficient when not fast...
     // TODO check CRC here
     // TODO rv = false;
   }
-  float raw = (buffer[0] << 8) + buffer[1];
+  uint16_t raw = (buffer[0] << 8) + buffer[1];
   temperature = raw * (175.0 / 65535) - 45;
   raw = (buffer[3] << 8) + buffer[4];
   humidity = raw * (100.0 / 65535);
@@ -76,16 +82,44 @@ uint16_t SHT31::readStatus()
 {
   uint32_t status = 0;
 
-  writeCmd(SHT31_READ_STATUS);
-  readBytes(3, (uint8_t*) &status);
+  writeCmd(SHT31_READ_STATUS);        // page 13 datasheet
+  readBytes(3, (uint8_t*) &status);   // 16 bit status + CRC
+  // TODO CRC check
   return status;
+
+  // bit - description
+  // ==================
+  // 15 Alert pending status
+  //    '0': no pending alerts
+  //    '1': at least one pending alert - default
+  // 14 Reserved ‘0’
+  // 13 Heater status
+  //    '0’ : Heater OFF - default
+  //    '1’ : Heater ON
+  // 12 Reserved '0’
+  // 11 Humidity tracking alert
+  //    '0’ : no alert - default
+  //    '1’ : alert
+  // 10 Temp tracking alert
+  //    '0’ : no alert - default
+  //    '1’ : alert
+  // 9:5 Reserved '00000’
+  // 4 System reset detected
+  //    '0': no reset since last ‘clear status register’ command
+  //    '1': reset detected (hard or soft reset command or supply fail)
+  // 3:2 Reserved ‘00’
+  // 1 Command status
+  //    '0': last cmd executed successfully
+  //    '1': last cmd not processed. Invalid or failed checksum
+  // 0 Write data checksum status
+  //    '0': checksum of last write correct
+  //    '1': checksum of last write transfer failed
 }
 
-// hard reset 0x0006 on addr 0x00 see datasheet
 void SHT31::reset()
 {
-  writeCmd(SHT31_RESET);
-  delay(1);  // table 4 datasheet
+  writeCmd(SHT31_SOFT_RESET);     // SHT31_HARD_RESET not implemented yet
+  delay(1);  // table 4 datasheet // 100ms for hardreset
 }
 
 void SHT31::heatOn()
@@ -98,6 +132,30 @@ void SHT31::heatOff()
   writeCmd(SHT31_HEAT_OFF);
 }
 
+void SHT31::requestData()
+{
+  writeCmd(SHT31_MEASUREMENT_SLOW);
+  _lastRequest = millis();
+}
+
+bool SHT31::dataReady()
+{
+  return ((millis() - _lastRequest) > 15);
+}
+
+void SHT31::readData()
+{
+  uint8_t buffer[6];
+  readBytes(6, (uint8_t*) &buffer[0]);
+
+  float raw = (buffer[0] << 8) + buffer[1];
+  temperature = raw * (175.0 / 65535) - 45;
+  raw = (buffer[3] << 8) + buffer[4];
+  humidity = raw * (100.0 / 65535);
+
+  _lastRead = millis();
+}
+
 //////////////////////////////////////////////////////////
 
 void SHT31::writeCmd(uint16_t cmd)

libraries/SHT31/SHT31.h

@@ -1,7 +1,7 @@
 //
 //    FILE: SHT31.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
+// VERSION: 0.1.2
 //    DATE: 2019-02-08
 // PURPOSE: Class for SHT31 I2C temperature humidity sensor
 //          https://www.adafruit.com/product/2857
@@ -16,7 +16,7 @@
 #include "Arduino.h"
 #include "Wire.h"
 
-#define SHT31_LIB_VERSION "0.1.0"
+#define SHT31_LIB_VERSION "0.1.2"
 
 class SHT31
 {
@@ -33,18 +33,28 @@ public:
   uint32_t lastRead() { return _lastRead; };
 
   void reset();
+
+  // do not use heater for long periods,
+  // use it for max 3 minutes to heat up
+  // and let it cool down an equal period.
   void heatOn();
   void heatOff();
 
   float humidity;
   float temperature;
 
+  // ASYNC INTERFACE
+  void requestData();
+  bool dataReady();
+  void readData();
+
 private:
   void writeCmd(uint16_t cmd);
   void readBytes(uint8_t n, uint8_t *val);
 
   uint8_t   _addr;
   uint32_t  _lastRead;
+  uint32_t  _lastRequest;   // for async interface
 };
 
 #endif

libraries/SHT31/examples/SHT31_async/SHT31_async.ino

@@ -0,0 +1,54 @@
+//
+//    FILE: SHT31_I2Cspeed
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.0.1
+// PURPOSE: demo
+//
+// HISTORY:
+
+#include "Wire.h"
+#include "SHT31.h"
+
+uint32_t start;
+uint32_t stop;
+
+SHT31 sht;
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("SHT31_LIB_VERSION: \t");
+  Serial.println(SHT31_LIB_VERSION);
+
+  Wire.begin();
+  sht.begin(0x44);
+  Wire.setClock(100000);
+  uint16_t stat = sht.readStatus();
+  Serial.print(stat, HEX);
+}
+
+void loop()
+{
+  for (uint32_t I2Cfreq = 100000; I2Cfreq < 900000; I2Cfreq += 50000)
+  {
+    Serial.print(I2Cfreq/1000);
+    Wire.setClock(I2Cfreq);
+    test();
+  }
+}
+
+
+void test()
+{
+  start = micros();
+  sht.read(true);         // default = true/fast       slow = false
+  stop = micros();
+  Serial.print("\t");
+  Serial.print(stop - start);
+  Serial.print("\t");
+  Serial.print(sht.temperature, 1);
+  Serial.print("\t");
+  Serial.println(sht.humidity, 1);
+  delay(100);
+}

libraries/SHT31/keywords.txt

@@ -0,0 +1,22 @@
+#######################################
+# Syntax Coloring Map For AnalogKeypad
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+
+SHT31	KEYWORD1
+
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+
+#######################################
+# Instances (KEYWORD2)
+#######################################
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+

libraries/SHT31/library.json

@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/Arduino.git"
   },
-  "version":"0.1.0",
+  "version":"0.1.2",
   "frameworks": "arduino",
   "platforms": "*",
   "export": {

libraries/SHT31/library.properties

@@ -1,5 +1,5 @@
 name=SHT31
-version=0.1.0
+version=0.1.2
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Library for SHT31 Temperature Humidity