Many, many shields which do not meet these guidelines will still work with Netduino (since Netduino's digital pins are 5V tolerant and can drive quite a bit of power). These are "best practices" for new shield designs.
"Works with Netduino" best practices
For a product to qualify for this category, it will need to meet the following guidelines:
- Inputs 0 - 3.3V (or 0 - 5.0V) digital signals from Netduino
- Outputs 0 - 3.3V analog/digital signals to Netduino
- Sources power from external power supply or Netduino's 5V/3.3V power headers...not from IO pins
- If not using built-in Netduino functionality, sample code must be available in C# (from manufacturer...or from community and posted on the Netduino Wiki)
We may add other qualifications to this list over time if the need arises. The goal here is to make it easy for accessory manufacturers to assure consumers of their compatibility with Netduino hardware.