No power on DIO ports

[adias670]

We have a roborio 2.0 for our FRC team. We tried using the DIO ports for the first time today and found that we're getting 0 volts out of them. We measured across all the ports using a multimeter. The PWM ports provide power. We attached a Rev Robotics More Board (https://www.revrobotics.com/rev-11-1100/) to the MXP port and were able to get power on the DIO ports that are on the More Board. We vacuumed all the open slots/ports on the roborio. We also opened it up and looked carefully to see if we could find anything floating inside. We found nothing and nothing changed as far as the voltage measurements.

Any suggestions?

Thanks,

  - Antonio

[BoKnows]

It sounds like you're using a similar bit of code to push to both the DIO and the MXP DIO.

I'd ask for a quick sanity check to make sure the pins are set to be output and have a high driven to them rather than acting as an input currently.  I suspect you've already done that but want to check that 😃 

[adias670]

Thanks for replying. We noticed the problem originally when trying to use a beambreak sensor (https://www.adafruit.com/product/2168), which we read using the wpilib DigitalInput class (https://first.wpi.edu/wpilib/allwpilib/docs/release/java/edu/wpi/first/wpilibj/DigitalInput.html). We sanity checked without any code, just measuring with a multimeter across the ground/5v pins.

We also checked on other roborios that we have from previous years' robots and they all measured and functioned as expected. Is there something that we may have done to enable the DIO rail on those roborios that we failed to do here? I had thought it was default always on but maybe I missed something.

Thanks,

  - Antonio

[BoKnows]

Unless you're driving something to a pin, the pins aren't guaranteed to provide any specific voltage.  Some may show the maximum voltage when the pins "rail."  Some may show zero.  

You'd want to add some quick code to just set the pin high and then use the DMM to measure across that.  It'd let us confirm that when you send a value to the pin, you're not seeing it when measured.

[adias670]

That's interesting. Is that documented somewhere? It's not what we've experienced with our existing roborios. 

[adias670]

The beam break sensors we're using are certainly sending signals and we're unable to read those through the 10 DIO ports. We believe that's because they're not being powered. We've verified they're working with other roborios. Are you looking for something more?

[BoKnows · Accepted solution]

It's not documented anywhere that I'm aware of.  Though, I also don't know of any documentation suggesting it should be high.

The test you attempted should be sufficient.  I sent you a message to talk through getting a replacement.