Merge pull request #20 from things-nyc/fix-await-calibration

Reset on begin and read coefficients only after calibration

Author: ladyada

Adafruit_BME280.cpp

@@ -66,8 +66,19 @@ bool Adafruit_BME280::begin(uint8_t           addr)
     if (read8(BME280_REGISTER_CHIPID) != 0x60)
         return false;
 
+    // reset the device using soft-reset
+    // this makes sure the IIR is off, etc.
+    write8(BME280_REGISTER_SOFTRESET, 0xB6);
+
+    // wait for chip to wake up.
+    delay(300);
+
+    // if chip is still reading calibration, delay
+    while (isReadingCalibration())
+          delay(100);
+
     readCoefficients(); // read trimming parameters, see DS 4.2.2
-    
+
     setSampling(); // use defaults
 
     return true;
@@ -338,6 +349,18 @@ void Adafruit_BME280::readCoefficients(void)
     _bme280_calib.dig_H6 = (int8_t)read8(BME280_REGISTER_DIG_H6);
 }
 
+/**************************************************************************/
+/*!
+    @brief return true if chip is busy reading cal data
+*/
+/**************************************************************************/
+bool Adafruit_BME280::isReadingCalibration(void)
+{
+  uint8_t const rStatus = read8(BME280_REGISTER_STATUS);
+
+  return (rStatus & (1 << 0)) != 0;
+}
+
 
 /**************************************************************************/
 /*!

Adafruit_BME280.h

@@ -187,6 +187,7 @@ class Adafruit_BME280 {
 
     private:
         void readCoefficients(void);
+        bool isReadingCalibration(void);
         uint8_t spixfer(uint8_t x);
 
         void      write8(byte reg, byte value);