Ok, so I’ve been trying to resolve this for a while now to no avail… does anyone have input on how to power the IR board?
The document they gave us says “Positive power supply voltage input. Voltage should be in the range 7-15 volts DC. Your power supply will have to be independent, for example, a 6 x AA battery pack, 9V battery, 12V battery, bench top supply, or other.”
But then again, I don’t think other batteries are allowed on the robot, are they? I’ve noticed several teams on here said they’ve wired this thing directly to their power distribution block, but I don’t want to do that and show up to a regional and be told it’s not the way we’re supposed to do it (and vice versa for using a different battery) Does anyone have some insight on this?
Two basic FIRST legal choices are allowed (and adequate) for powering the IR Receiver:
Power from the 12v breaker panel, protected by a 20amp breaker (power from the main 12v battery)
Power from one of the 7.2v “PWM Output” pins on the Robot Controller (powered by the 7.2v backup battery)
Choice #2 does risk having too little power as the backup battery is close to the lower limit, but will work if you keep the backup battery fully charged at all times. Choice #1 could also fail if a motor surge drops the main battery voltage too low, so keep that battery fully charged as well!
There is a third legal variation to power the board from one of the 5v Robot Controller pins (powered by the main 12v battery and backed by by the 7.2v backup battery), e.g., Analog Inputs or Digital I/O pins, however, this does involve modifying the IR board to bypass the on-board 5v regulator. The advantage here is double battery coverage since any extreme 12v battery drop will be covered by the backup battery.
I guess we’ll go with the circuit breakers, then. I have no problem wiring it that way, I just don’t want to get there and find out it’s wrong. Our team should be submitting a question to the Q&A Fora as well, just to be certain, but it certainly sounds like we’ll be fine just using the system 12v power… I’ll post back here if I hear anything further. Thanks guys!
Q: 3) The Inspection List has raised a few questions in meeting we held. here they are:
Does the IR circuit has to be used through a 20A breaker?
A: Question 3: The IR receiver circuit must be protected by a 20-amp circuit breaker (see Rule <R55>).
This is probably the most related rule:
8.3.8 - Control, Command & Signals System
<R82>
Inputs to custom circuits can be connected to the following sources:
• Branch circuit breaker outputs
• Speed controller or relay module outputs
• PWM, relay or digital outputs on Robot Controller
• Switches, potentiometers, accelerometers, sensors, and other additional permitted electronics.
Ah, well, I didn’t see that when I went through looking for information on it. Well then, we won’t bother the GDC with another useless question. Thanks for your help, Mark.
