How do i wire limit switch

to an nxt.

If it’s for your minibot using the NXT only adds weight and slows the minibot down but if you are going to do it, with some very minor programming (2-3 blocks) you can use the touch sensor. If you need help programming in NXT-G, I can help.


I just replied to a different thread but it looks like you need some more basic help… Start here and work through some of the tutorials there…

As far as I know, you can not wire a COTS limit switch to an NXT controller. You need to use the Lego Touch Sensor…



You can use the HiTechnic Prototyping board:


You could but I could not find it listed in the Approved Tetrix Parts list.



You could but I could not find it listed in the Approved Tetrix Parts list.


Check Team Update #1
I may be wrong when I read “BB.NXT compatible sensors and
related connectors/cables.” as legalizing the Prototype Board


The NXT part is the Touch Sensor.

I think that most inspectors would go by the Approved Tetrix list for Tetrix components.

I see your point but would defer to a GDC official Q&A if you have one.

Maybe Big Al can chime in here…


Sorry, but the protoboard is not on the approved Tetrix parts list. The latest version of the manual (Rev K) includes this…

<R92> The following items are the only permitted materials for use on the MINIBOTS:
A. TETRIX components that are not in violation of any other rules, (Tetrix components are listed in Approved Tetrix Parts at


BB. NXT compatible sensors and related connectors/cables,

Followed by this blue box…

Please note that the Rule <R92> only allows specific Tetrix components. While Tetrix components are a subset of FTC components, it is essential to realize that not all FTC parts are Tetrix parts. As such, not all FTC parts are permitted on the MINIBOT. Please be sure to vet your components against the above list before constructing your MINIBOT.

It has been quite common for teams to confuse legal FRC allowed list with the FTC allowed list. Under FTC the protoboard is a legal part.

i just need to know how to wire a limit switch to an nxt and how to wire it to the minibot motors as well.

Do you need to use the NXT? You could wire a three way light switch such that it turns off the motors when it is depressed.

Cut a standard NXT cable in half, and solder the COM/COMMON/GND/GROUND pin of your limit switch to either the white or the black wire, and solder the NO or NORMALLY OPEN pin of your limit switch to the other wire.

Let me know if that doesn’t work, I’m not completely sure it would.

Although the rule allows the use of the NXT, I believe the rules may be written so that NXT compatible sensors are to be used with the NXT brick.
If you do some research, you will see that many if not most minibots do not use an NXT as it only adds weight. Standard limit switches can be used to directly power the two FTC motors and you can use home lighting switches as well.
Who to wire IEC Limit Rotary Switch PN: AAP2T51Z11
with the motor TITREX
I foind that
A 4-wire sensor is designed for use of at least three of the four wires. Wire usage is based on connecting the sensors power (+), common (-), and either a Normally Open (N.O.) or Normally Closed (N.C.)output, or both outputs. The sensor will not operate as a 2-wire device.
My Q is whitch nomber should be the (-) of the M- witch nomber is M+



The diagram you show is a standard limit switch with a N.O. pair of contacts and a N.C. pair of contacts. The 11 and 12 contacts are Normally Closed. The 13 and 14 contacts are Normally Open. There is no power connection. There is no common. It will indeed work perfectly well as a two-wire device.