From b6369f7a6be8c84e3c85831541ed9ae8c9c7e3a2 Mon Sep 17 00:00:00 2001
From: ladyada <limor@ladyada.net>
Date: Thu, 21 Jan 2016 20:04:35 -0500
Subject: [PATCH] burst read temp & pressure

---
 Adafruit_BME280.cpp | 52 +++++++++++++++++++++++++++++++++++++++------
 Adafruit_BME280.h   |  9 ++------
 2 files changed, 48 insertions(+), 13 deletions(-)

diff --git a/Adafruit_BME280.cpp b/Adafruit_BME280.cpp
index 38f8698..f662916 100644
--- a/Adafruit_BME280.cpp
+++ b/Adafruit_BME280.cpp
@@ -192,6 +192,50 @@ int16_t Adafruit_BME280::readS16_LE(byte reg)
 
 }
 
+
+/**************************************************************************/
+/*!
+    @brief  Reads a 24 bit value over I2C
+*/
+/**************************************************************************/
+
+uint32_t Adafruit_BME280::read24(byte reg)
+{
+  uint32_t value;
+
+  if (_cs == -1) {
+    Wire.beginTransmission((uint8_t)_i2caddr);
+    Wire.write((uint8_t)reg);
+    Wire.endTransmission();
+    Wire.requestFrom((uint8_t)_i2caddr, (byte)3);
+    
+    value = Wire.read();
+    value <<= 8;
+    value |= Wire.read();
+    value <<= 8;
+    value |= Wire.read();
+
+  } else {
+    if (_sck == -1)
+      SPI.beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
+    digitalWrite(_cs, LOW);
+    spixfer(reg | 0x80); // read, bit 7 high
+    
+    value = spixfer(0);
+    value <<= 8;
+    value |= spixfer(0);
+    value <<= 8;
+    value |= spixfer(0);
+
+    digitalWrite(_cs, HIGH);
+    if (_sck == -1)
+      SPI.endTransaction();              // release the SPI bus
+  }
+
+  return value;
+}
+
+
 /**************************************************************************/
 /*!
     @brief  Reads the factory-set coefficients
@@ -230,9 +274,7 @@ float Adafruit_BME280::readTemperature(void)
 {
   int32_t var1, var2;
 
-  int32_t adc_T = read16(BME280_REGISTER_TEMPDATA);
-  adc_T <<= 8;
-  adc_T |= read8(BME280_REGISTER_TEMPDATA+2);
+  int32_t adc_T = read24(BME280_REGISTER_TEMPDATA);
   adc_T >>= 4;
 
   var1  = ((((adc_T>>3) - ((int32_t)_bme280_calib.dig_T1 <<1))) *
@@ -258,9 +300,7 @@ float Adafruit_BME280::readPressure(void) {
 
   readTemperature(); // must be done first to get t_fine
 
-  int32_t adc_P = read16(BME280_REGISTER_PRESSUREDATA);
-  adc_P <<= 8;
-  adc_P |= read8(BME280_REGISTER_PRESSUREDATA+2);
+  int32_t adc_P = read24(BME280_REGISTER_PRESSUREDATA);
   adc_P >>= 4;
 
   var1 = ((int64_t)t_fine) - 128000;
diff --git a/Adafruit_BME280.h b/Adafruit_BME280.h
index af2661e..e480cb9 100644
--- a/Adafruit_BME280.h
+++ b/Adafruit_BME280.h
@@ -24,13 +24,7 @@
 #endif
 
 #include <Adafruit_Sensor.h>
-
-#ifdef __AVR_ATtiny85__
- #include "TinyWireM.h"
- #define Wire TinyWireM
-#else
- #include <Wire.h>
-#endif
+#include <Wire.h>
 
 /*=========================================================================
     I2C ADDRESS/BITS
@@ -150,6 +144,7 @@ class Adafruit_BME280
     void      write8(byte reg, byte value);
     uint8_t   read8(byte reg);
     uint16_t  read16(byte reg);
+    uint32_t  read24(byte reg);
     int16_t   readS16(byte reg);
     uint16_t  read16_LE(byte reg); // little endian
     int16_t   readS16_LE(byte reg); // little endian