My latest tinkering is to connect a 0.96" OLED display to my UDOO Neo Linux/Arduino computer to display soil humidity. After 3 nights of hacking around the Adafruit SSD1306 libraries I got the display code to compile and run on the UDOO Neo Arduino M4 processor. I kept getting a compile error when compiling the Adafruit SSD1306 library (see the gory details below). After removing the offending code from the library I was able to get the display working. Next I connected the Hygrometer and with some code I had the reading displaying in 30 minutes. Now I can see how moisture the soil is. To get the Adafruit SSD1306 to compile and run on the UDOO Neo Arduino I commented out the unused SPI define and begin code. I was getting errors the the setClockDivider and beginTransaction could not be imported. Since I am using I2C and not SPI I just commented out the SPI code.