Control of Decorations (Led displays)

[Al Skierkiewicz]

Originally Posted by DavidGitz

<R42> Each power-regulating device (speed controller or relay module) shall control one and only one electrical load (motor, actuator or compressor).
Exception: Multiple low-load, pneumatic solenoid valves may be connected to a single relay module. This would allow one relay module to drive multiple pneumatic actions. No other electrical load can be connected to a relay module used in this manner.

From my understanding, a spike can control 2 circuits only if they are low-load, pneumatic solenoid valves. So you cannot control 2 different LED's (although I'm sure the current requirement is comparable).

If someone here disagrees, please let me know. Right now we have 3 relays for this purpose and I would not mind going down to 2!

David,
The multiple "low load" solenoid valves relate to the Crio solenoid/relay module. The Spike Relay module can control electrical loads up to 20 amps and can control multiple solenoids using the wiring suggested above.
See...http://content.vexrobotics.com/docs/...uide-sep05.pdf for a full description.
As long as you keep each LED string below 10 amps each and follow all other robot rules, you should have no problem.
Please be advised, bright LED strings, flashy decorations, or objects that mimic or emit light that can interfere with other robots using optical sensors may be viewed as objectionable under other FRC rules. Inspectors, refs or other officials may require you to disable them.

[DavidGitz]

Al - Thanks for the clarification. I agree the current requirement will not even be close to exceeding the limitations of the spike relay, ours are about 30 mA max.

I may be "lawyering" these rules too much, but I am trying to make sure that I understand them fully. The document you specified was the one I was discussing as well. That document only specifies controlling 2 devices if they are solenoid valves. Obviously that document is not FIRST official but is just a reference.

So you are saying that the "single relay module" from the rules is not referring to the spike relay but is instead referencing the solenoid breakout, as seen here? I don't think this is true, and I think that I am misreading your post (although you did say "Crio solenoid/relay module").

So the question remains, are LED's (and their associated circuitry) considered an actuator? If so, then only one module may be controlled through a spike relay. If not, then there are no rule limitations (in this context, obviously practicality,safety and electrical limits apply) to how many be controlled by one relay.

I feel that I am beating this to death, and I will defer to your wisdom as an outstanding Robot Inspector.

[Al Skierkiewicz]

David,
The interface you linked to is simply an add on module to the NI 9472 Crio module that came in your KOP. Each output can be accessed through the linked interface using PWM style connectors. The 9472 module has certain current limitations, 0.75 amps per output or 6 amps total for the module.
The Spike can handle significantly more current. However, I have yet to see a robot design that would require a large number of solenoids firing all at once from the same trigger signal. Since the Spike can handle currents up to 20 amps total (it is fused for 20 amps) it is commonly used for controlling higher current loads. Teams have used them to control decorations in the past. If you are proposing just one 30 ma LED, it is an overkill for the Spike I know. Unfortunately, there is no convenient way to power the LED through current hardware. I would ask the question of the Q&A as I don't remember this particular application has been approached before. Ask if you can use the solenoid module (9472) to drive LED loads and ask if you can use a relay or digital output of the digital sidecar to drive a custom circuit that would power the LED. (A simple transistor would suffice for the later.) I don't remember any rule off the top of my head that would prevent either, but will check later when I have more time.

BTW, the linked module is required to interface to the NI 9472 that came in KOP. There is an interface module included in your KOP.

[Alan Anderson]

Originally Posted by Al Skierkiewicz

...ask if you can use a relay output of the digital sidecar to drive a custom circuit that would power the LED. (A simple transistor would suffice...)

If you're going to do a custom driver circuit anyway, don't bother with abusing the relay outputs. Just use a Digital I/O pin.

[Joe Ross]

Originally Posted by DavidGitz

So the question remains, are LED's (and their associated circuitry) considered an actuator? If so, then only one module may be controlled through a spike relay. If not, then there are no rule limitations (in this context, obviously practicality,safety and electrical limits apply) to how many be controlled by one relay.

I'm not sure how something that doesn't move or cause motion could be considered an actuator.

[elbuo]

I just wish to clarify something,

If I use 5v lights, can I attach them directly to my DSC in the DIO side? That way I would just open and close to channel to turn on or off a light.

[Alan Anderson]

Originally Posted by elbuo

If I use 5v lights, can I attach them directly to my DSC in the DIO side?

The DIO pins are connected directly to the NI 9403 module, with a 10k pullup resistor to +5 volts. The module is capable of sourcing 2 milliamps per channel.
The Digital Sidecar 5v power supply is rated at 3A total. I don't know how much of that is available for use by external circuitry.

[Al Skierkiewicz]

Alan and elbuo,
The 9403 module is speced at source and/or sink of 2 ma per output. Not enough to drive an LED.