Fingerprint sensor constantly flashing.

[nsafai]

Is it possible to get the fingerprint sensor to stop flashing incessantly? e.g. it only flashes once it detects the presence of a fingerprint on the sensor? The datasheet also mentions "finger detection" but I couldn't find any documentation around how to use this.

All of the sample code works except the LED control sample code: https://github.com/adafruit/Adafruit-Fingerprint-Sensor-Library/blob/master/examples/ledcontrol/ledcontrol.ino which makes me wonder if that portion of the library is somehow broken?

• Arduino board: Arduino Uno

• Arduino IDE version: Arduino 1.8.14

• List the steps to reproduce the problem below:

  • Connect your Arduino and upload this sketch: https://github.com/adafruit/Adafruit-Fingerprint-Sensor-Library/blob/master/examples/ledcontrol/ledcontrol.ino Notice that this sketch is broken and does not control the fingerprint sensor LEDs successfully. Again, every other sample sketch works perfectly except this one.
  • Sensor: https://smile.amazon.com/gp/product/B07BQ9VNWR/ref=ask_ql_qh_dp_hza

[RobMel98]

I've got the same problem, just with a different sensor. Mine is this one: https://www.adafruit.com/product/4750.

If I use for example the enroll sketch, the sensor is fadding in and out with a blue color and if a stored fingerprint is recognized it lights up in green and after a few seconds jumps back to the blue fading.

But if I upload the ledcontrol sketch the sensor is just doing it's blue fading but it does not react to the color commands of that sketch.

I also tried the library from DFRobot (https://github.com/DFRobot/DFRobot_ID809) because their sensor looks simular to my one but with this library the connection was not possible (I also tried the example queryDeviceBPS but this also doesn't work).

Here is a link to the adafruit forum, where some great guys tried to help me, unfortunately still with no success: https://forums.adafruit.com/viewtopic.php?p=944032#p944032

My Arduino board is also an Arduino Uno and I'm using the Arduino IDE version 1.8.19

[bdh8]

RobMel98: take a look at my response to adafruit/Adafruit_CircuitPython_Fingerprint#48 This module (adafruit 4750) does not respond to LED commands, but can be put in "stand-by" mode with a couple extra components which turns off the breathing blue LED and has a touch sensor (White and blue leads) that can be used to tell you when to take it out of stand-by mode.

nsafai: from what I can see on Amazon at the link you gave, your sensor may work the same with Vtouch and Sout being the leads for the touch sensor (blue and yellow that the images never connect to anything).

[nsafai]

@bdh8 thanks! I appreciate the followup on this. I ended up getting the round fingerprint sensor adafruit recommends on their site and the LED code works fine now. With the new sensor I was able to get LED to flash only when it's scanning a fingerprint, it's a bit quality of life upgrade. Highly recommend it!

[caternuson]

Closing. Seems resolved. The PID 4651 sensor is the only one that currently has actual LED control.