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[FRC Blog] myRIO Expansion Port - What's the Deal?

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Today’s blog post, a long one, was written by Kate Pilotte, FRC Kit of Parts Manager, who’s facilitating the new control system efforts.

Hopefully, you’ve heard by now that all registered and paid FRC Teams are receiving new control system devices in their 2015 Kickoff Kits (this will include at least a roboRIO, dual-mode access point/bridge, a Power Distribution Panel, a Voltage Regulator Module, a Pneumatic Control Module, and four Talon SR motor controllers. The contents of the Kickoff Kits are typically confidential until Kickoff, but hopefully I can get away with saying that much!

Image credit: ni.com/frc

One of the features of the roboRIO is the MXP, or myRIO Expansion Port. It’s called out in the image above as the “Custom Electronics Port.” This port allows expansion of control system I/O based on the team’s specific needs. Specifically, the pinout is shown below. Did you notice that pins 11, 13, 15, 17, 18, 22, 26, 27, 29, and 31 can be used for DIO or PWM?

Image credit: ni.com/frc

This kind of feature is new to FRC. We recognize that if we didn’t say anything to the community about how it can be used – technically and legislatively – until Kickoff, it wouldn’t be much use as the build season just isn’t long enough to accommodate such an effort. For that reason, we’d like to let you know a few things ahead of time.

We had three driving priorities when drafting the rules and defining controller behavior (even though we’re not sure if the second priority is a real word…):

Safety – implementation of the MXP must mitigate risk of injury to team members and volunteers. Specifically, when a robot is disabled, nothing on the robot should move. When the robot receives a disable command, it will disable all PWM and Relay ports (which are the only ports by which actuators may be controlled). All other ports (SPI, Analog In, Digital I/O, RS-232, I2C, Ethernet, USB, and CAN) will remain enabled (although the “enable” token will not be sent over CAN, effectively disabling devices on the CAN). This includes the 10 pins (in yellow in the image above) that may be used for PWM via the MXP, even if the user has opted to not use them for PWM or actuators.
Inspect-ability – Volunteer Inspectors are able to quickly and sufficiently assess a robot’s compliance with the rules.
Parity – Teams cannot gain considerable advantage by employing highly expensive solutions.
Given those bullet points, we’ve drafted this preliminary set of MXP relevant definitions and rules.

Preliminary Defintions

ACTIVE DEVICE or CIRCUIT: Any device or circuit capable of dynamically controlling and/or converting a source of electrical energy by the application of external electrical stimulus.

MXP: myRIO Expansion Port (aka Custom Electronics Port)

PASSIVE DEVICE or CIRCUIT: Any device or circuit whose capability is limited to the conduction and/or static regulation of the electrical energy applied to it (e.g. wire, splices, connectors, printed wiring board, etc.).

Preliminary Rules

MXP1: If a motor or sevo is controlled via the MXP, it must be connected by one of the following methods:

directly to any PWM pins,
via a network of PASSIVE DEVICES and/or CIRCUITS used to extend the PWM pins, or
via one approved ACTIVE DEVICE.
In a nutshell? It means if you’re using the MXP for sensors, lights, or anything else that isn’t going to actually move or cause movement, the sky’s the limit and you can do whatever custom circuitry you like via the MXP. Remember though that upon disable, the 10 pins that double as PWM pins will also be disabled – so don’t use those pins for anything you’ll rely on while your robot’s disabled.

As soon as you decide to use those PWM pins to cause robot parts to move, you’ll have to use an approved device that FIRST has pre-vetted and listed in the manual as legal. This is to ensure that when those 10 pins are disabled, that disable signal that’s so important to us isn’t obscured or interrupted. It’s also an attempt to keep the inspection of that clean, simple, and objective.

In addition to the MXP specific rules, you can also expect rules comparable to those published in the past. Examples include, but aren’t limited to, the following points:

Robots must be controlled by and only by the roboRIO.
We don’t anticipate rules that prohibit co-processors (have at ‘em!), provided commands originate from the roboRIO to configure, enable, and specify all operating points for all power regulating devices. This includes devices legally wired to the CAN-bus.
Custom electronics must use appropriately sized wire.
Limits on motors, actuators, and power regulating devices for actuators will be defined.
Pneumatic solenoid valves and electric solenoid actuators may not be controlled via the MXP.
Custom electronics and circuits must not modify the power pathways between the battery, PDP, VRM, PCM, motor controllers, roboRIO, RSL, wireless bridge, main breaker, relays, or motors.
Only the robot’s wireless bridge may be used for wireless communication.
We anticipate approving a handful of devices, but we don’t have a specific limit (that will be driven by the number and quality of proposals received). So, what does a device have to do to be an approved Active Device? Here’s the requirements list:

The Active Device must be designed and produced such that
PWM pins must be a direct pass-through
the breakouts for PWM pins are visibly obvious
The Active Device must be previously approved by FIRST. To seek approval, please submit a comprehensive proposal to FIRST via frcparts@usfirst.org.
Approvals will be received up through November 14, 2014. FIRST will review and provide feedback and legality decision within one week of receipt. Legality is considered confidential until disclosed publicly by FIRST (which will be published by Kickoff, at the latest).
To be considered complete, proposals must include the following components
At least 5 device samples.
A description of how inventory and distribution will be managed such that devices will be commercially available to the FRC community.
Submitted by or in conjunction with a company that meets the 2014 definition of "VENDOR".
Preliminary documentation (e.g. user guide, specification sheet, etc.) and description of other relevant user resources (e.g. videos, websites, etc.)
Device pricing.
There’s no prohibition on sending descriptions, documentation, and other information ahead of the samples.

While it’s not required, we do recommend that any Active Device accommodate a pass-through for any unused pins so users can still access them. We don’t have spare systems to lend out to Active Device developers. If you need a system for development or testing, we recommend you team up with a Beta Team that has the bandwidth and is willing to work with you.

NI has provided a comprehensive roboRIO MXP Developer’s Guide (alpha version) with all the tools and guidelines you'll need to create your custom MXP board. The dev kit includes free access to NI's Multisim circuit SPICE software, Ultiboard, PCB layout software, templates, examples, and tutorials that will help you create any kind of board you want.

So, there you have the status of the MXP, as we know it today, for the 2015 FRC season. I will include an admittedly frustrating disclaimer that, if we learn anything via the ongoing beta testing efforts or feedback from the community, we do reserve the right to revise any language, rules, positions, etc. presented above.

If you have any questions about this (surely I didn’t address everything in on blog!), we’ve created a forum in the 2015 FRC Beta Test Forum specifically for MXP discussion - please post your thoughts and questions there. If you’re interested in developing an Active Device and have questions about the approval process or your specific device, please send your question to frcparts@usfirst.org.

Thank you!

MXP legality information for 2015. Also confirmation that the PCM will be included in the kickoff kit, and we will recieve a generous supply of Talon SR speed controllers which should help offset any Victor SP/Talon SRX availability concerns

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Looks fairly reasonable. Passive devices can be connected in any way the teams see fit. Motors can be connected directly if done through passive electronics (nice to see that we can build our own breakout boards to optimize the interface to our own robot, as long as it consists of passive components only), while any active device requires FRC approval.

Given the relatively short timeframe for device approval, I wonder if CTR, Vex, and other historical electronics manufacturers will be soliciting active device concepts from the community?

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

I think this blog post answers another much asked question...

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this will include at least a roboRIO, dual-mode access point/bridge, a Power Distribution Panel, a Voltage Regulator Module, a Pneumatic Control Module, and four Talon SR motor controllers

So everyone gets a PCM!

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

I'm actually confused. So if the PWM ports are used to control a motor, It has to come through an active approved device? Or can a passive device be used to control a motor if it doesnt interfere with the signal at all?

Because according to this

via a network of PASSIVE DEVICES and/or CIRCUITS used to extend the PWM pins, or

it looks like you can directly connect, but further down it says if it moves it has to be an active approved device.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Thad House (Post 1401206)

As I understand it, as long as your connection device does not have any components that would qualify it as an ACTIVE DEVICE, you can custom make whatever you want with no approval. This would include anything that essentially serves as a "converter cable," routing pin outputs through conductors and presenting a more usable interface appropriate for your system. Only if you are using your board to do something that would qualify as an active device (for example, performing some kind of pre-processing of digital inputs on a board that also outputs PWM, swapping PWM outputs based on a co processor output, etc.) would you have to get your setup approved as an ACTIVE DEVICE.

I am curious as to what the limits of what could be considered a passive device would be. For example, would LED indicators to show PWM out status constitute an "active device?" Diodes are considered active electronic components due to their differing response to different polarity, although they would not be used as such in this application.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

The blog post (unofficially) presents the interpretation of ACTIVE DEVICE:

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As soon as you decide to use those PWM pins to cause robot parts to move you’ll have to use an approved device that FIRST has pre-vetted and listed in the manual as legal.,

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by BigJ (Post 1401211)

The blog post (unofficially) presents the interpretation of ACTIVE DEVICE:

Asked about this in the comments on the blog, Kate responded. Sounds like passive connection to PWM pins that drive motors, as I described, is legal.

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Thanks for the question - and my apologies for the uncertainty...

The second sentence should read "As soon as you decide to use those PWM pins to cause robot parts to move (and you're not connecting via options A or B), you’ll have to use an approved device that FIRST has pre-vetted and listed in the manual as legal.” The text above will be revised.

The bare PCB with headers sounds like it meets the definition of Passive Device – so you should be fine with what you’re proposing.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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In a nutshell? It means if you’re using the MXP for sensors, lights, or anything else that isn’t going to actually move or cause movement, the sky’s the limit and you can do whatever custom circuitry you like via the MXP.

This is extremely exciting, I can't wait to start prototyping circuits with my team.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

FYI, if anyone is wanting some tutorials on circuit design, I took this class this past year, and it was great (back then, we paid for these videos). The software used is called KiCAD, which is an absolutely free and open source eCAD suite of software.

https://www.youtube.com/user/context...view=0&sort=da

Alternatively, you can use the Altium Designer donation teams get every year, but I find it hard to rely on getting that donation every year.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Jon Stratis (Post 1401189)

I think this blog post answers another much asked question...

So everyone gets a PCM!

You're very welcome, that happened because I preordered our board from Andymark last night... But now we'll have a spare!

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Maybe this is a stupid question but why do I need to use a SPICE simulation to figure out what the ports are doing? Why can't I just have a table with drive strengths and speeds and such?

And why do they assume that your circuit will be flat on the roborio and tell you clearances for stuff under where they think your PCB will be? Can't they just let you figure it out from the mechanical drawings?

I feel like a ton of effort has been put into this for no reason.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by SoftwareBug2.0 (Post 1401284)

Something that laying flat allows is stackability of modules, which is something I hope we can implement. It would be nice to stack things like co-processors on top of a sensor board (or vice versa).

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

So something like an Talon or an spike would be an active device. If you wanted to use a beefier relay than a spike, that would be an active device & would require submittable & approval.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by FrankJ (Post 1401325)

So something like an Talon or an spike would be an active device. If you wanted to use a beefier relay than a spike, that would be an active device & would require submittable & approval.

FIRST probably won't allow any custom components in the power pathway. Only official KOP relays and speed controllers.

Rather, an active device is one that modifies the signal sent to the Talon or Spike (or Jag or Vic). If the connection to a speed controller is not directly from the roboRIO pins or MXP headers, through passive devices (PCBs, bumpers, etc.), to the speed controller signal port, then the intermediate device has to be approved in advance.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by compwiztobe (Post 1401332)

I have long since stop trying to predict what the GDC will do. :) But speed controllers & relays fit into the blogs definition of an active device. The proposed rule says one active device. NOT one active intermediate active device connected to a second active device. The blog has an approval process for active devices. Part of the approval process seems to be that you will need the resources to make the device commercially available to all the teams. So the approval bar starts off pretty high.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by FrankJ (Post 1401340)

I can see where you're getting this reading, but look at the other two options for controlling a motor or servo. It says directly connected to PWM pins or connected through passive devices, which obviously doesn't mean no speed controller/relay at all. The intent seems to be that all actuators are still controlled by the approved controllers (Talons, Vics, Jags, and Spikes), while the signals to these controllers can be supplied in the 3 ways described (direct connection, passive connection, or one approved active device).

But I agree both that the wording doesn't say this exactly and that we can't predict all of the GDC's intent or future actions.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Does anyone know what kind or type of connector is used? Its a 17x2 pin connector, but not sure on anything else of it. Trying to find a source for a female plug to adapt to it. Thanks

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by ice.berg (Post 1401352)

Does anyone know what kind or type of connector is used? Its a 17x2 pin connector, but not sure on anything else of it. Trying to find a source for a female plug to adapt to it. Thanks

The blog links to the NI MXP developers guide at https://decibel.ni.com/content/docs/DOC-39578 which gives several mating connectors.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

I think "passive" in First terms would include extension headers for the pins, wires, pcb traces, etc. Anything that does not modify the pathway. You make a daughter board that covers all the pins, but passively passes through the used pins. perhaps with a locking PWM connector that has the power & ground so you use a conventional PWM cable. Without allowing for the in the rules, an inspector somewhere would not let you do that.

The wording is the way it to allow for servos & VEX motors which take a direct PWM input well as conventional brushed motors & controllers.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by SoftwareBug2.0 (Post 1401284)

Maybe this is a stupid question but why do I need to use a SPICE simulation to figure out what the ports are doing? Why can't I just have a table with drive strengths and speeds and such?

Well you don't HAVE to use anything. There are a lot of tools out there for creating schematics and layout. The NI tools however offer that, plus a lot more, including simulation. If you're going into electrical engineering (particularly analog design), SPICE is a really valuable tool.... and you get it for free! Also the template for the board outline is already loaded for you.

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And why do they assume that your circuit will be flat on the roborio and tell you clearances for stuff under where they think your PCB will be? Can't they just let you figure it out from the mechanical drawings?

Yes, you can, and calling out backside clearance does not replace the need to do a good job on the stack up analysis and mechanical tolerance calculations. However it does remind people that the default board position offers limited backside space, and if you want backside components, or long through-hole leads, etc. you will need to move to a taller connector.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Joe Ross (Post 1401353)

The blog links to the NI MXP developers guide at https://decibel.ni.com/content/docs/DOC-39578 which gives several mating connectors.

Appreciate it, Thanks!

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by compwiztobe (Post 1401346)

I can see where you're getting this reading, but look at the other two options for controlling a motor or servo. It says directly connected to PWM pins or connected through passive devices, which obviously doesn't mean no speed controller/relay at all.

Servos do connect directly without an intermediate speed controller. So do some servo-like motors, though those might not be legal actuators.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by FrankJ (Post 1401325)

So something like an Talon or an spike would be an active device. If you wanted to use a beefier relay than a spike, that would be an active device & would require submittable & approval.

Please bear in mind that "active device" and "ACTIVE DEVICE" are two different animals.

The former encompasses an awful lot of things
The latter is defined as something that fits onto the MXP and needs FIRST pre-approval.

Carry on...

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by crake (Post 1401355)

Well certainly; I don't have to use the MXP port at all. And if National Instruments wants to provide a simulator and a board layout tool then that's fine too. But these things shouldn't have to be connected. Perhaps there's a link someplace I've missed but it looks like if you want any more than the voltage range and intended use you must use SPICE. For example, how many amps can I draw on each of the pins? What are the supported speeds of the serial port? These should be easy to spell out in text. I should not have to run a simulation to find out.

I agree that SPICE is useful. It's just not clear to me how the MXP port would cause you to use SPICE if you'd been given a proper data sheet. If I'm speccing a filter a simulation is great to go along with the graph for what the cutoff is supposed to look like. But in the MXP port there should't be anything interesting analog wise: everything is either digital, straight to an ADC, or straight to a DAC. And I doubt that the digital stuff is fast enough that the use of SPICE is warranted.

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Originally Posted by crake (Post 1401355)

Do people actually screw this up? There is something to be said for making documentation accessible but please assume that high school students have mastered the ruler.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by SoftwareBug2.0 (Post 1401407)

Do people actually screw this up? There is something to be said for making documentation accessible but please assume that high school students have mastered the ruler.

All. The. Time. It's really awkward when you forget to account for the thickness of a structural member in design and have to account for it in hardware with a sawzall. Been there, done that. Ever since, when working that sort of project, it's been "Did I account for ALL of the intermediate stuff when making this length?"

The other factor, of course, is that it's quite possible to mess up numbers with the mechanical drawings. (Trust me--even with a good drawing, sometimes the only thing saving your bacon is some really good measuring to interpret the drawing.) By saying that X needs Y distance of clearance, they are taking an aspect of the drawings that may or may not be clear to the average EE/programmer and saying "Pay attention to this. You need to take this into consideration. The drawings are less idiot-resistant than we'd like to be able to make them."

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by SoftwareBug2.0 (Post 1401407)

Do people actually screw this up? There is something to be said for making documentation accessible but please assume that high school students have mastered the ruler.

Thats a bold assumption. Being a high school drafting and shop teacher has shown many things to me, most importantly is that rulers and fractions elude even the best AP students sometimes.

Try an experiment just for fun, next time you are around high school students ask them what the decimal equivalent of 7/16" is and see how many can pull it off without a calculator or the internet.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by MrBasse (Post 1401442)

...
Try an experiment just for fun, next time you are around high school students ask them what the decimal equivalent of 7/16" is and see how many can pull it off without a calculator or the internet.

Or have them half 13/16. Not really a knock on the quality of students or teaching. There is a art or craft to all of this that takes time & practice to learn.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by EricH (Post 1401414)

I guess I put things too strongly. Sure, people are fallible but maybe we would be better off letting them fail occasionally. Sometimes airports have moving walkways with a speakers at the end to announce that you should get off. Most of the time it's an annoyance. Too often I read through the documenation and feel like I'm listening to one of those speakers.

I think it's appropriate that a person would have to look ahead and see where they have to start walking again. And I think it's appropriate that people would have to determine clearances themselves. I say this as a person who has started daydreaming on one of those walkways and noticed the end by a foot coming out from under me. (It's actually kind of amusing; I recommend trying it sometime.);)

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Sorry to be getting to this late. The MXP is a standard developed for myRIO and utilized for roboRIO. At least some of the drawings, tools, and documents are there because myRIO is used for college level design classes. If you don't need SPICE and don't want to expose the kids to it, I don't think anyone is going to twist your arm. If your comment is that some basic information is missing, please ask and I'm sure it can be provided.

As for the mechanical design. There are inserts for screwing the MXP card to the roboRIO, and the assumption was that this would be a common approach. The MXP docs also defines a planar variant that is intended to be used on myRIO side connectors. It is the team's design, and if you would rather have the board extend up into the robot, that is your choice, but unless the board is tiny, I suspect it will better serve as a lesson in how not to do mechanical design. Thus the recommendation is to use the ninety degree connection and screw the accessory to the roboRIO.

The primary goal with the MXP was to open up and more fully support the daughter-card or co-processors that a few teams implement. This can be limited to physical connector selection or can include integrated sensors and even processing. Even with the documentation, there is a chance of failure. There is also an opportunity for more open discovery and innovation. Please let us know how to improve it.

Greg McKaskle

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Greg McKaskle (Post 1401664)

Ah, this makes more sense to me now. When I was introduced to SPICE it was rather sterile; having something like this might have made it more interesting. Is there someplace that says how much current I can draw from one of the pins?

It took me a second to figure out what mechanical devices were being referred to but I think it's these:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/211702
http://sine.ni.com/nips/cds/view/p/lang/en/nid/212318

I can see why someone who was used to using those might need to be reminded about clearance issues when switching to something that lays flat.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Yes, those links are what I was referring to as planar boards.

If you poke around on that page, specifically on the board-only version, you'll see find that it uses the 90 degree connectors and has templates for accessories that using the mating 90 degree connector.

If you download the pdf Specifications, you'll find voltage, current, resolution, timing, and much more. Please keep in mind this is for a related product, and not the roboRIO. I'm not the HW guy and I don't actually have the details either. But this should get you in the ballpark.

Greg McKaskle

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Just out of curiosity, are the horizontal and angled connector boards compatible in that I can swap one connector for the other? IE I have a board with a right angle connector for the MyRIO, can I de-solder that one, put in a vertical and now use it with a RoboRIO?

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by timytamy (Post 1401850)

Sort of. You can swap the connectors, but then you may have to swap the orientation of the PCB (vertical vs. horizontal).

If you design a horizontal MXP for packaged myRIO-1900 and want to use this in the bare-board myRIO-1950 or roboRIO then you either have to:

a) use the same connector, but now the MXP is in a vertical "shark fin" orientation.
b) swap the connector, but now the MXP needs to be upside down to maintain proper signal connections, but it is horizontal.
c) swap the connector and spin the PCB so the signals are flipped. This gives you a horizontal board that isn't upside down.

This was a source of a very long debate during development. You could either flip the signals on the roboRIO/myRIO PCB when you go horizontal to vertical, or you flip the signals on the MXP boards. Maintaining a consistent pinout on "host side" of MXP was seen as more important, so that was the direction we went, but it does result in this little dance that happens when you go from horizontal to vertical MXP board-to-board connections.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Greg McKaskle (Post 1401829)

If you download the pdf Specifications, you'll find voltage, current, resolution, timing, and much more. Please keep in mind this is for a related product, and not the roboRIO. I'm not the HW guy and I don't actually have the details either. But this should get you in the ballpark.

For anyone looking, the relevant details seem to start on page 4 here:
http://www.ni.com/pdf/manuals/376047a.pdf

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

What does the user button do on the roboRIO?

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by orangelight (Post 1401905)

What does the user button do on the roboRIO?

Whatever you program it to ;) (it's just a button readable from user code)

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by RufflesRidge (Post 1401909)

Whatever you program it to ;) (it's just a button readable from user code)

That seems cool...

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

I just looked at both (myRIO and RoboRIO), and compared the pinouts and they appear they are not exactly the same as the myRIO standard. Or am I wrong?

http://zone.ni.com/reference/en-XX/h...ector_pinouts/

Compare to here:

https://decibel.ni.com/content/docs/DOC-39578

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by cglrcng (Post 1404037)

They are the same. The only difference is the numbering convention and the notation that the DIO can also be used for PWM (which it can on the myRIO also, but is less important for that product).

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

I need to remind everyone that part of this rule is covered under the 2014
R53
CUSTOM CIRCUITS shall not directly alter the power pathways between the ROBOT battery, PD Board, motorcontrollers, relays, motors, or other elements of the ROBOT control system (items explicitly mentioned in R64). Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to the ROBOT’S electrical system is acceptable, if the effect on the ROBOT outputs is inconsequential.
I have to admit that even I forgot the implications here.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

So per rule R53 a high impedance input from say an ATMEGA88 uController connected to the PWM signal line to monitor signal status would be Legal? It would be on the team to be show to show the inspector that it was actually an input it was connected to.

Although the PWM signal line is not really a power path way so maybe not?

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Frank,
I think that would be a question for the GDC. In the past we always considered that rule for connections to the electrical power path not to the PWM path.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Actually if I wanted an PWM status indicator visible from the stands, I would hang a servo with a big arrow on a PWM splitter. Of course the only real difference there is the servo is a defined legal device.

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

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Originally Posted by Al Skierkiewicz (Post 1404041)

Did you mean to be replying to this thread? http://www.chiefdelphi.com/forums/sh...130303&page=11

Re: [FRC Blog] myRIO Expansion Port - What's the Deal?

Actually both Joe. The way I understand the statements, adding a power supply (regulator) or modifying any of the pins by use of an active device, will need the approval process of FIRST Engineering. The ultimate test is to insure that the device is inspectable and that everyone is sure that it does not allow parts to move when the robot is disabled.