diff --git a/README.md b/README.md
index 162620a..e6de0ae 100644
--- a/README.md
+++ b/README.md
@@ -116,6 +116,26 @@ The option -nostartfiles instructs the linker to not use the standard system sta
  If you patch the function to call , bl __libc_init_array then you might get an undefined reference to _init.
  https://answers.launchpad.net/gcc-arm-embedded/+question/224709
 
+# BME280 i2c drivers
+
+To use these you must 
+    #include "OBME280.h"
+
+    // After MCUInit()
+    i2c_bme280_begin();
+
+    float temp=i2c_bme280_read_temp();
+    float pressure=i2c_bme280_read_pressure();
+    float rh=i2c_bme280_read_rh();
+    printf("RH %2f Temp %2f , pressure %2f\r\n",rh,temp,pressure);
+
+To force new readings you should use,
+    i2c_bme280_force_readings();
+
+Note that this uses the same i2c as the MEMS sensor. The 3 
+bottom pins is GND, SCL, SDA
+
+
 # Blackmagic Single Wire Debug
 
 Allows flashing over wifi and single step the code with gdb
diff --git a/lib/obme280/OBME280.h b/lib/obme280/OBME280.h
index ec7ee24..a4be555 100644
--- a/lib/obme280/OBME280.h
+++ b/lib/obme280/OBME280.h
@@ -2,6 +2,12 @@
 #ifndef __BME280_H__
 #define __BME280_H__
 
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+
 #include "stdint.h"
 
 
@@ -204,5 +210,8 @@ FOR POWER MODE  */
 
 
 
+#ifdef __cplusplus
+}
+#endif
 
 #endif
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