Can't get limit switch to work on Teensy 4.1

Using Arduino Project Guidance
1

I am working on an inverted pendulum project and have gotten all of my electronics connected and working with the Teensy 4.1 EXCEPT (surprisingly) a simple limit switch. It is a CYT1073 micro limit switch (Link: Cylewet 25Pcs AC 1A 125V 3Pin SPDT Limit Micro Switch Long Hinge Lever for Arduino (Pack of 25) CYT1073: Amazon.com: Industrial & Scientific). I tried to get it to work with all my other electronics connected to the Teensy but it wasn't working so I disconnected everything and left only the teensy itself and the limit switch. I have the limit switch COM connected to ground and NC connected to a digital pin (I have tried many pins and all didn't work). I have also tried INPUT, INPUT_PULLUP, and INPUT_PULLDOWN within my code (attached). I have also tried using a 10K ohm pullup resistor. NONE of it worked. When I test the same exact configuration on my Arduino UNO it works, but not on the Teensy. The crazy thing is that I've used this same exact limit switch with a different Teensy 4.1 with the same exact code and configuration and it worked just as I expected. And yes, I've tried using another CYT1073 limit switch thinking it was maybe faulty but it still did not work. Help would be VERY much appreciated. Also, if it helps, I have attached my very simple wiring diagram.

#include <Arduino.h>
int limitswitch = 6;

void setup() {
  Serial.begin(9600);
  pinMode(limitswitch, INPUT_PULLUP);
}

void loop() {
  int val = digitalRead(limitswitch);
  Serial.println(val);
}

TCYT
TCYT390×502 43.4 KB

2

It looks to me as though you have the limit switch connected to pin 19, not pin 6.

teensy41_4
teensy41_4772×224 66.3 KB

1 Like
3

I wish it were that easy but no I've tried many pins, I just picked a random pin to connect to the limit switch. But thank you I should have labeled the connection in the image better as well as not include a specific pin in both the code and the drawing.

4

Do you have an LED and 470 to 1000 Ohm resistor?

5

I have LEDs but only 330 and 10k ohm resistors. I guess I can put two or more 330's in series. What are you suggesting?

6

Just a data point: uploaded your sketch to a Teensy 4.1 here, hooked up a lever switch and you know what happened... it worked just fine.

Are you sure you've got your board selection and options set properly?

Edit: this is a completely off the wall never in a million years question: you haven't by any chance got one of the original almost 5 year old now beta test boards, have you? The ones where only the ground on pin 1 is hooked up?

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7

330 should work.
Connect the limit switch common to 5 volts +, the LS NC to the LED anode (long leg), the LED cathode (short leg) to resistor, other end of resistor to 5V - (GND). Does the LED light? If you press the LS lever, does the LED go OFF?

8

Yes when unpressed the LED is on and when pressed the LED is off. This works.

9

So you have a good limit switch, now post a clear picture of your project with all pin and terminal labels shown.

1 Like