Interface with Littlefuse 55505 Hall Effect Flange Mount Geartooth Speed Sensor

I am trying to get the D21G to interrupt on CH1 with this sensor.

I have 12V input to device on V-/V+

and the sensor being powered by the same lines. then the black and white wire from the sensor going into CH1.

I can't get it to increment the counter when triggering the sensor.

I have tested that the interrupt is working with a jumper from V+ to CH1 and it does indeed increment.

I have also tested that the sensor is putting out a voltage when sensing a metal tooth, it hits about 10Volt when not connected. and when connected to CH1 about 3.8volt

I thought it might be to low of a voltage but i triggered CH1 with a 5 volt input and it worked as well.

Any suggestions or thoughts would be appreciated, thanks.

#include <Indio.h>
#include <Wire.h>

#include <UC1701.h>
static UC1701 lcd;

volatile int counter = 0;

void setup() {

  SerialUSB.begin(9600);
  lcd.begin();
 
  Indio.digitalMode(1, OUTPUT); //  Clear CH1 to LOW
  Indio.digitalWrite(1, LOW);  // Clear CH1 to LOW
  Indio.digitalMode(1, INPUT); // Set CH1 as an input with interrupt
 
  Indio.digitalMode(2, INPUT_MASKED);     
  Indio.digitalMode(3, INPUT_MASKED);     
  Indio.digitalMode(4, INPUT_MASKED);    
  Indio.digitalMode(5, INPUT_MASKED);     
  Indio.digitalMode(6, INPUT_MASKED);
  Indio.digitalMode(7, INPUT_MASKED);
  Indio.digitalMode(8, INPUT_MASKED);

  attachInterrupt(8, count, FALLING);       // D8 attached to the interrupt of the expander

}

void count() {
//  SerialUSB.println("trigger");
  counter++;
}

void loop() {
  lcd.setCursor(1, 3);
  lcd.print(counter);
//  delay(100);
}

Josh Nijenhuis
Josh Nijenhuis
24
| 0 0 0
Asked on 1/17/19, 12:59 AM
0
vote
155 Views

Hi, the INDIO datasheet says we need >11V to trigger HIGH and

Tom
on 1/17/19, 2:49 AM

Hi, I'm not sure why you're seeing only 3.8V on the sensor's output when CH1 is configured as INPUT; could you measure the current?

The INDIO datasheet says we need >11V to trigger HIGH and <3V for LOW. 

According to your sensor's datasheethttps://www.littelfuse.com/~/media/electronics/datasheets/hall_effect_sensors/littelfuse_hall_effect_sensors_55505_datasheet.pdf.pdf it outputs VDD-2 on HIGH, so that's indeed only 10V. There is an internal pull-up resistor already, but maybe you can try to add an external 1K, to increase the output voltage. When the sensor goes LOW, it would need to supply 12mA to counter the pull-up, which seems within its specs (it mentions 20mA, but also 10.5mA as max). 

Tom
Tom
5375
| 0 0 1
Answered on 1/17/19, 2:59 AM
1
vote

It worked to put in a 1K external pull up. Thank you. would be nice if that little tidbit from the INDIO datasheet was in the interrupt section of the software docs possibly.

Josh Nijenhuis
on 1/18/19, 12:19 AM

thanks for the feedback, i added a note in the digital I/O section on github

Tom
on 1/18/19, 6:04 AM

Your answer

Please try to give a substantial answer. If you wanted to comment on the question or answer, just use the commenting tool. Please remember that you can always revise your answers - no need to answer the same question twice. Also, please don't forget to vote - it really helps to select the best questions and answers!

Ask a Question

Keep Informed

About This Forum

This community is for professionals and enthusiasts of our products and services.

Read Guidelines

Question tools

54 follower(s)

Stats

Asked: 1/17/19, 12:59 AM
Seen: 155 times
Last updated: 1/17/19, 2:59 AM