- fixed issue #123

Author: RobTillaart

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 @@ class SHT31
  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