upm: added list of known sensor issues

Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

README.md

@@ -63,3 +63,5 @@ C/C++ API Documentation
 The C/C++ documentation is available [here](http://iotdk.intel.com/docs/master/upm/).
 
 Version @ref changelog [here](docs/changelog.md).
+
+List of @ref knownissues [here](docs/knownissues.md).

docs/knownissues.md

@@ -0,0 +1,50 @@
+Known Issues                        {#knownissues}
+===============
+
+Every once in a while we come across sensors that will not pair well with
+a specific board. This means their are either incompatible or will work only
+under specific settings. This is a list of such sensors and known workarounds
+if they exist.
+
+#### Grove Sensors
+
+ * **Grove I2C Touch Sensor** v1.3 is incompatible with the Intel Edison using
+ the Arduino board, but will work with the Mini-breakout if supplied with at
+ least 4V. Revision v1.2 works well on all Intel boards.
+ * **Grove Nunchuck** only works with the Intel Galileo boards and is unusable
+ on the Intel Edison boards.
+ * **Grove 3-Axis Digital Gyroscope** (ITG-3200) is not compatible with the
+ Intel Edison Arduino board but will work with the Mini-breakout.
+ * **Grove 3-Axis Digital Accelerometer** (ADXL345) only works with the Intel
+ Edison Arduino board when powered from the 3.3V line.
+ * **Grove 96x96 OLED Display** will not work on the Intel Edison with Arduino
+ breakout.
+ * **Grove 128x64 OLED Display** will not work on the Intel Edison with Arduino
+ breakout.
+ * **Grove Barometer** (BMP085) has an unstable connection on the Intel Edison
+ using the Arduino breakout and does not run properly.
+ * **Grove 6-Axis Accelerometer & Compass** (LSM303) fails to write to the
+ configuration register properly and returns invalid data.
+ * **Grove I2C ADC Converter** does not show up on the I2C bus on the Intel
+ Edison with the Arduino board.
+ * **Grove I2C Motor Driver** is not compatible with the Intel Galileo due to
+ the inability to change the I2C bus speed to 100 KHz.
+ * **Grove CO2 Sensor** will return zeroed data and is unusable on the Intel
+ Galileo.
+ * **Grove BLE** (HM-11) does not return data on the Intel Galileo board.
+
+#### Adafruit Sensors
+
+ * **Adafruit Motor Shield** (1438) will not get detected on the I2C bus when
+ connected to the Intel Edison with an Arduino breakout.
+
+#### Other Sensors
+
+ * **MPU9150** might return inaccurate data.
+
+Some I2C sensors seem to add too much capacitance to the SDA line of the Intel
+Edison Arduino breakout board, thus the signal essentially becomes stuck to a
+logic 1. When this happens, any other sensors connected to the I2C bus will be
+rendered useless too. There is no universal solution for this issue, but under
+most cases the same sensor will work just fine on the Intel Edison Mini. Using
+the same sensor but from a different vendor can also work in some cases.