Revision 5:691e06db489f, committed 2016-11-29

Comitter:

jont

Date:

Tue Nov 29 18:54:29 2016 +0000

Parent:

4:ddcaa259e65b

Commit message:

Replaced original getTemperature Routine as it was returned strange values

Changed in this revision

diff -r ddcaa259e65b -r 691e06db489f BME280.cpp
--- a/BME280.cpp	Tue May 12 13:32:09 2015 +0000
+++ b/BME280.cpp	Tue Nov 29 18:54:29 2016 +0000
@@ -5,6 +5,10 @@
  *  @version 1.0
  *  @date    06-April-2015
  *
+ *  29 November 2016 
+ *  Toyomasa Watarai code Modified  by jon trinder jont@ninelocks.com 
+ *  readtemperature routine replaced
+ *
  *  Library for "BME280 temperature, humidity and pressure sensor module" from Switch Science
  *    https://www.switch-science.com/catalog/2236/
  *
@@ -100,6 +104,13 @@
     DEBUG_PRINT("dig_H = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_H1, dig_H2, dig_H3, dig_H4, dig_H5, dig_H6);
 }
  
+ 
+ /* 
+As Thomas routine was giving me weird values I rewrote it to look mostly like the adafruit 
+arduino code, which in turn is a lot like the bosch datasheet 
+jon Trinder
+*/
+ /*
 float BME280::getTemperature()
 {
     uint32_t temp_raw;
@@ -124,6 +135,45 @@
  
     return (tempf/100.0f);
 }
+*/
+
+// new version of getTemperature jont@ninelocks.com November 2016 
+float BME280::getTemperature()
+{
+    int32_t var1, var2, T;
+    int32_t adc_T;
+    float temp_as_float;
+    char cmd[4];
+    cmd[0] = 0xfa; // temp_msb
+    i2c.write(address, cmd, 1);
+    i2c.read(address, &cmd[1], 3);
+
+    //jons slow painful shifting of bits to make it readable
+    adc_T = cmd[1];
+    adc_T <<= 8;
+    adc_T |= cmd[2];
+    adc_T <<= 8;
+    adc_T |= cmd[3];
+     
+    //from here more or less same as ada and bosch
+ 
+    adc_T >>= 4;
+    
+    var1  = ((((adc_T>>3) - ((int32_t)dig_T1 <<1))) *
+       ((int32_t)dig_T2)) >> 11;
+    
+    var2  = (((((adc_T>>4) - ((int32_t)dig_T1)) *
+         ((adc_T>>4) - ((int32_t)dig_T1))) >> 12) *
+       ((int32_t)dig_T3)) >> 14;
+    
+    t_fine = var1 + var2;
+    
+    T  = (t_fine * 5 + 128) >> 8;
+    temp_as_float = T/100.0;
+    return temp_as_float;   
+}
+
+
  
 float BME280::getPressure()
 {

diff -r ddcaa259e65b -r 691e06db489f BME280.h
--- a/BME280.h	Tue May 12 13:32:09 2015 +0000
+++ b/BME280.h	Tue Nov 29 18:54:29 2016 +0000
@@ -1,6 +1,5 @@
 /**
  *  BME280 Combined humidity and pressure sensor library
- *
  *  @author  Toyomasa Watarai
  *  @version 1.0
  *  @date    06-April-2015
@@ -10,6 +9,8 @@
  *
  *  For more information about the BME280:
  *    http://ae-bst.resource.bosch.com/media/products/dokumente/bme280/BST-BME280_DS001-10.pdf
+ *
+ * 
  */
  
 #ifndef MBED_BME280_H
@@ -18,7 +19,7 @@
 #include "mbed.h"
 
 //#define _DEBUG
-#define DEFAULT_SLAVE_ADDRESS (0x76 << 1)
+#define DEFAULT_SLAVE_ADDRESS (0x77 << 1)
 
 #ifdef _DEBUG
 extern Serial pc;
@@ -72,7 +73,7 @@
      *
      */
     float getTemperature(void);
-
+    
     /** Read the current pressure value (hectopascal)from BME280 sensor
      *
      */