2015 Beta Testing - The Components are Here.

[Mark McLeod]

Originally Posted by timytamy

On the diagram under the custom electronics port, it shows that the DIO has been pulled up to 3v3, implying that it uses 3v3 logic levels. Could you clarify, what logic levels does the RoboRIO use on both the main IO and MXP port? I believe I saw a voltage selection jumper on some alpha pics, implying that voltage is selectable, does this work and does it affect both the main-IO and MXP or just one?

Here's the jumper. The DIO power is 5v by default.

Also your MXP pin-out is out of date. It appears that the roboRIO will get a different configuration to the myRIO (https://decibel.ni.com/content/docs/DOC-30419)

Thanks, I updated that diagram.

[jhersh]

Originally Posted by timytamy

On the diagram under the custom electronics port, it shows that the DIO has been pulled up to 3v3, implying that it uses 3v3 logic levels. Could you clarify, what logic levels does the RoboRIO use on both the main IO and MXP port? I believe I saw a voltage selection jumper on some alpha pics, implying that voltage is selectable, does this work and does it affect both the main-IO and MXP or just one?

The jumper only affects the DIO power pins on the built-in DIO connectors. The MXP has both power supply rails included, so the board may use either one as needed. The I/O itself in both MXP and built-in DIO is not affected by the jumper. All DIO is 3.3 V drive and 5 V tolerant.

[timytamy]

Originally Posted by jhersh

The jumper only affects the DIO power pins on the built-in DIO connectors. The MXP has both power supply rails included, so the board may use either one as needed. The I/O itself in both MXP and built-in DIO is not affected by the jumper. All DIO is 3.3 V drive and 5 V tolerant.

Does this means that we can use 5v devices (provided they read a 3v3 signal as high) without any risk of damaging the RoboRIO? I'm just thinking about various sensors and custom circuits that were designed for 5v that may perform differently at 3v3. They can probably be re-designed but it would be nice if that wasn't necessary.

[jhersh]

Originally Posted by timytamy

Does this means that we can use 5v devices (provided they read a 3v3 signal as high) without any risk of damaging the RoboRIO? I'm just thinking about various sensors and custom circuits that were designed for 5v that may perform differently at 3v3. They can probably be re-designed but it would be nice if that wasn't necessary.

yes

[BitTwiddler]

Originally Posted by Tom Line

Absolutely!!!!! That's why we put them up, and that's the whole point of Beta.

Thanks Tom. I appreciate it. The pictures are good and clear.

[Jared]

I'm looking at the power board/pneumatic bumper, and it seems to me that the pneumatics bumper has a relay/other driver built in to power the compressor. It also is powered from a fuse, which looks like
https://www.eficonnection.com/eficon.../mini_fuse.jpg , which is smaller than the spike fuse, meaning our normal 20 amp resetting breakers won't work here.

How do we replace the 20 amp fuse shown in (http://www.team358.org/files/program...mages/PDP2.jpg) that picture with an auto resetting one?

[RufflesRidge]

Originally Posted by Jared

How do we replace the 20 amp fuse shown in (http://www.team358.org/files/program...mages/PDP2.jpg) that picture with an auto resetting one?

You don't...

[Jared]

Originally Posted by RufflesRidge

You don't...

If you use a 20 amp not resetting fuse, as shown in the picture and the robot's battery is a little low, it trips when the compressor starts, leaving your robot without a compressor in the middle of the match. It's happened to me before.

The people who make this know this (as the manual has an exception for this), so either I'm not understanding how this works, or their will be issues with the fuse getting blown during matches. I'm betting that I don't understand how this works, and was wondering if somebody who actually has the part knows how it would work.

[Trent B]

Given both the pneumatic module and the power distribution board are connected to the RoboRIO via CAN, there is a possibility that these devices are monitoring the current to prevent fuse blowouts that the comparatively simplistic implementation "on off with a relay" on the old system couldn't compensate for.

[Tom Line]

To my knowledge - we didn't see any blow fuses during Alpha testing.

The CTRE guys will need to answer this one. I'll fire them an email.

[Nate Laverdure]

You can get self-resetting circuit breakers in this form factor fairly easily.

Amazon
Grainger

[Jared Russell]

Originally Posted by Nate Laverdure

You can get self-resetting circuit breakers in this form factor fairly easily.

Amazon
Grainger

Self-resetting breakers usually do not trip as precisely as fuses. If the downstream circuits really cannot handle >20A, even for a second, you ought to use a fuse.

[Nate Laverdure]

Originally Posted by Jared Russell

Self-resetting breakers usually do not trip as precisely as fuses. If the downstream circuits really cannot handle >20A, even for a second, you ought to use a fuse.

Fine, but aren't we're talking about an application (powering the compressor) where self resetting circuit breakers have been used successfully for some time?

[Jon Stratis]

Originally Posted by Nate Laverdure

Fine, but aren't we're talking about an application (powering the compressor) where self resetting circuit breakers have been used successfully for some time?

With different hardware, yes. From what I've been told in the past, Vex (the makers of the spike relay) did specific testing with a circuit breaker to validate it as safe before FIRST allowed it to be used for compressors in the rules. That's the only reason teams were allowed to replace the provided fuse with a breaker for use with compressors.

For FRC usage, breakers, in general, are present to protect the wiring, not the components attached to that wiring. For this 20A fuse, it could protect the PCM from over-current if (for example) something gets shorted out... but my guess would be that the fuse is there to prevent the PDP from burning out by drawing too much current from those outputs. It's probably there to protect against a short much more than to protect downstream circuitry.

[cgmv123]

Originally Posted by Nate Laverdure

You can get self-resetting circuit breakers in this form factor fairly easily.

Amazon
Grainger

I'd be very surprised if replacing the PDB fuse with a breaker will be legal for competition.