This topic is a summary of the known issues with the Arduino part of the Neo on a Udoo released OS. The Neo Arduino processor is different than the Arduino Uno were it should be compatible with. In practice when you want to use some higher level usage of the Arduino features you run into issues. This topic is to summerise these to help each other with testing and solving these. Please do not ask questions here about problems! React in the linked topic or start a new topic and I will add it to this list that will be shortened as they are being solved! If I missed an issue or an issue is solved please react here. For already known and acknowledged issues see also the documentation pages Differences , String Issue and Porting Libraries 1. [SOLVED] Serial Connection /dev/ttyMCC unreliable (and other threads) 2. Interrupts unreliable. 3. Analog pins cannot be used as digital pins 4. ADC readings from A9 and M4 giving "wrong" values 5. Serial.write((int)0) not working 6. SPI arduino not working 7. [DOCUMENTED]Neo not reading Serial /dev/ttyMCC slows down Arduino M4 8. SOLVED - Servo.h has an error (temporary fix in topic) Libraries Next to issues is the unknown list of compatible libraries (see also doc Porting Libraries and topic Library Compatibility) Working Libraries are (if I forgot one please react here): Servo (with a problem, see #8) LiquidCrystal Wire Stepper (compile test only) Important libraries known not to work, as a reference the list of official Arduino libraries: SoftwareSerial Firmata Neopixels SPI (Current one based in V1.0, see #6) Onewire Other Related Issues CAN on A9 not working when a Arduino sketch is running on M4 Updated 12-01-2017: added Onewire as unsupported library.