I've been puling my hair out on this one for a week. I've connected a Grove motion sensor to the Pi2Grover board and am reading the pin with the code below, but the pin remains high regardless of the sense of the motion sensor (testing it with a logic probe). I've verified that the sensor is pulling the output pin (the yellow wire) high or low based on motion when it's not connected to the Pi2Grover board, so the sensor is working. But when connected to the Grove connector the pin (that's connected to the yellow cable) always stays high. In fact that pin is always high even if I initiate it with a GPIO_PUD_DOWN setting. It seems that pin stays high no matter how it's initialized and pulled by an external device. The code I'm using is below. What am I missing? Thanks.
Also - I'm guessing (although it doesn't appear to be documented anywhere) that the sharing of the ports (like D16 and D19 being on the same Grove connector) means that the primary wire (yellow) is connected to the first-numbered port and the secondary wire is connected to the second-numbered port. Is that right?