Revision 1:c6381a3f2d9a, committed 2022-02-14

Comitter:

reedas

Date:

Mon Feb 14 23:53:34 2022 +0000

Parent:

0:c46b3e0a8c2b

Commit message:

added floating point return values;

Changed in this revision

diff -r c46b3e0a8c2b -r c6381a3f2d9a SHT40.cpp
--- a/SHT40.cpp	Mon Feb 07 15:08:07 2022 +0000
+++ b/SHT40.cpp	Mon Feb 14 23:53:34 2022 +0000
@@ -1,4 +1,4 @@
-/**
+ /**
  * @author Andrew Reed 
  * 
  * Freeware --
@@ -82,4 +82,56 @@
     return (int)rh;
 
 }
+float SHT40::tempCF(void) {
 
+    char txBuff[2];
+    char rxBuff[6];
+
+    txBuff[0] = SHT4x_NOHEAT_HIGHPRECISION; // Triggers a temperature measure by feeding correct opcode.
+    txBuff[1] = SHT4x_NOHEAT_HIGHPRECISION >> 8;
+    i2c_->write((SHT40_I2C_ADDRESS << 1) & 0xFE, txBuff, 2);
+    thread_sleep_for(50); // Per datasheet, wait long enough for device to sample temperature
+    
+    // Reads triggered measure
+    i2c_->read((SHT40_I2C_ADDRESS << 1) | 0x01, rxBuff, 6);
+    thread_sleep_for(1);
+    
+    // Algorithm from arduino sht4x.h to compute temperature.
+    unsigned int rawTemperature = ((unsigned int) rxBuff[0] << 8) | (unsigned int) rxBuff[1];
+    rawTemperature &= 0xFFFC;
+
+    float tempTemperature = rawTemperature / (float)65536; //2^16 = 65536
+    float realTemperature = -46.85 + (175.72 * tempTemperature); //From page 14
+ 
+    return (float)realTemperature;
+
+}
+float SHT40::relHumidF(void) {
+
+    char txBuff[2];
+    char rxBuff[6];
+
+
+    txBuff[0] = SHT4x_NOHEAT_HIGHPRECISION; // send command.
+    txBuff[1] = SHT4x_NOHEAT_HIGHPRECISION >> 8;
+    i2c_->write((SHT40_I2C_ADDRESS << 1) & 0xFE, txBuff, 2);
+    thread_sleep_for(16); // delay to sample humidity
+    
+    // Reads measurement
+    i2c_->read((SHT40_I2C_ADDRESS << 1) | 0x01, rxBuff, 6);
+    thread_sleep_for(1);
+    
+    //Algorithm from sht4x.h.
+    unsigned int rawHumidity = ((unsigned int) rxBuff[3] << 8) | (unsigned int) rxBuff[4];
+
+    rawHumidity &= 0xFFFC; //Zero out the status bits but keep them in place
+    
+    //Convert to relative humidity
+    float RH = rawHumidity / (float)65536; // two bytes worth to float
+    float rh = -6 + (125 * RH); // adjustment values as per sht4x.h
+    rh = min(max(rh, (float)0.0), (float)100.0);
+
+
+    return (float)rh;
+
+}
\ No newline at end of file

diff -r c46b3e0a8c2b -r c6381a3f2d9a SHT40.h
--- a/SHT40.h	Mon Feb 07 15:08:07 2022 +0000
+++ b/SHT40.h	Mon Feb 14 23:53:34 2022 +0000
@@ -94,6 +94,11 @@
       
     //Reads the relative humidity, input void, outputs and int.
     int relHumid(void);
+     //Reads the temperature, input void, outputs an int in celcius.
+    float tempCF(void);
+      
+    //Reads the relative humidity, input void, outputs and int.
+    float relHumidF(void);
     
     /* @ToDo populate a struct that returns temp and humidity in one call
      * struct tempHumid{