Yes, the Arduino is still running off the computer's USB, though I do have a wall plug for it. But, haha, eventually we'll have to run it off of the robot's power. We have a 5V stepper thingie, a duplicate of the one the radio-thingie uses. (Can you tell I'm getting out of my area?) This will have to wait until after school tomorrow for the electronics crew to construct.
The differences in grounds, if I may guess: The robot ground is the 12V battery (except the first regional week of Lunacy, when it would be the field, and not in a good way
). The Arduino ground is the USB port, or the wall power, which is not the same common ground. I don't know why this difference produces the output I've shown.
Just to recap, if the Arduino is powered from the robot, that means it's grounded to the robot. So if the PWM data wire from the cRIO/sidecar gets split to Arduino pin 7 and also to a resistor and on to an Arduino ground, that ground is also grounded back to the robot, so everything is equal.
Or (thinking further on this) should it be grounded back to the PWM wire back to the sidecar? And if I send 4 or 5 PWM signals to the Arduino, each signal wire gets a separate resistor and back to the PWM.
And just to be sure, the cRIO's DIO sends a solid HI/LOW down that wire? That output I showed is
not what I should be seeing?