Sensors and design

[Sovr]

Hello, team 3539 byting bulldogs are a rookie team, I personally build lots of microcontroller based robots. The question I have is what are the limits of sensors and I could go as far as building my own pcb board for various sensor circuits. Another thing what is the output voltages and currents of the Crio? Thank you a lot in advance !

[techhelpbb]

I am certainly not speaking from any authority, but when we make parts electronically for the cRIO, we open source the design. Such as the encoder splitter we worked on...and a few other things I hope we open up for everyone's examination.

So in this sense, it doesn't step on any rules about things designed before the start of the build season...it doesn't exclude other people from learning or contributing...and it makes it closer to a COTS system (Complete/Commercial Off The Shelf) system.

For more about COTS:
"A COTS item must be a standard (i.e. not custom order) part commonly available from the VENDOR, available from a non-team source, and available to all teams for purchase."

I can certainly see how some might not agree with my interpretation of the COTS rules, but it's not very hard to openly sell these items, even if you open source the process of developing it. This was one of the first years we ever really ran into a situation that warranted the development of any additional hardware and that anyone really sunk their teeth into trying to achieve it (so to be honest...other than research there are probably things in this process I might not be aware of).

Your other question is extremely broad. I suggest you review the extensive documentation for the cRIO. There are I/O ports on the Digital Sidecar, the Analog Bumper, and the cRIO itself (the serial and ethernet ports). Also there are ports on the Jaguar speed controls.

[tagayoff]

Quote : Another thing what is the output voltages and currents of the Crio?

For the specs on these see the attached images. These have to do with the various plug-in cards to the CRIO.

Quote : The question I have is what are the limits of sensors and I could go as far as building my own pcb board for various sensor circuits.

Yes, but you need to follow the power guidelines in the rules <R34> -<R48>

[WizenedEE]

We only had 3.3V accelerometers lying around, so I build a board with a 3.3V regulator, and the GDC said it was fine.

The two supplied voltages, however, are 5V and 12V. The 12V must be protected by a 20A circuit, and I think the 5V can supply 2 or 3 amps.

The C-RIO has 15 analog inputs, and 24ish digital input/outputs.

You are not allowed to use anything on a a robot that was built (not bought) before the start of build season.. so this includes any PCBs you made. However, I'm not so sure about sites like BatchPCB, where you give them a design and then they make it for you, and then will make it for anyone else.. technically, any team can buy from them, so it's probably fine.

You are allowed to use pretty much any sensor (note that exposed lasers are illegal), but be warned that with many mechanical folk on the team, they might not let you rely on your geiger counter that's attached to an accelerometer to move the drive wheels (how ridiculous, I know).

[Al Skierkiewicz]

SOVR,
What you are asking is covered under the rules for custom circuits and the electrical rules in general. You may use COTS sensors wired to a custom circuit if you wish. Items are of course limited by the cost rules as well. i.e. no more that $3500 total for the robot with no single part costing more than $400.

[Sovr]

Thank you very much for the info, I will take everything that everyone said to thought !

[Daniel Jones]

If you do end up designing your own PCB, consider using Altium. They have sponsored FRC with free licenses to teams for the past several years, and I have had a good experience with their software.
http://www.altium.com/frc2011/