Our program defines nx pin 16 as input pin. We set pin mode as falling status and expect that if The pin status changes from high to low, our callback registered will be called .
The connection outside the NX is as follows(designed by our hardware engineer):
The line(i.e. Trig_IN1) in the red circle designed to connect with nx pin 16.
We find a strange phenomenon
if Trig_IN1 not connects with nx pin 16, the period siginal is normal, The signal is as follows
But When Trig_IN1 connects with nx pin 16, the period siginal is abnormal, The high level become 1.6V not 3.3V, and the falling can’t be detected( we guess 1.6V regard as low) The signal is as follows,
We also do a experiment to change the resistantor in the red rectangle(0.3K, 20 K), it also can’t work
Is there something beyond the export, direction, and value writing that needs to be done to use the GPIO pins with the Dev kit?