Comments: Fingerprint Scanner (GT-521Fxx) Hookup Guide

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  • Interfacing Library for .NET

    We recently released an interfacing library in .NET for the Fingerprint Scanner (GT-521Fxx). The library is completely open source under MIT license.

    Library Features

    • All documented commands are implemented (2018-06-25)
    • Operations are all asynchronous
    • No dependencies
    • MIT License
  • Loved the earlier GT-511C1R... apart from the fact that it just didn't work at all well for me right at the "source"... it didn't scan my fingerprints very well. Everything else was first class, and very sophisticated. (With that come the fact that hooking into the interface is not trivial, but it IS (very) "do-able".

    As this device seems to use the same, or nearly the same SDK_Demo (Windows) software, I am hoping that it has all of the strengths of the old device.

    Have people found, once they have mastered the SDK_Demo software, and the fairly trivial hookup issues, that this reads prints well? Anyone with experience of this and the older device have any comments to share?

    • The new version of the fingerprint should function the same as long as you connect to the pins sufficiently. I did have some issues scanning fingerprints a few times but it was similar with any other fingerprint scanner that I've tested (i.e. pressing too hard, not placing the finger sufficiently on the scanner, etc.). It should be linked in the troubleshooting section => [ https://learn.sparkfun.com/tutorials/fingerprint-scanner-gt-521fxx-hookup-guide/troubleshooting ].

      There are some minor updates in the SDK-Demo software, scanner's features, and PCB. You should not notice a difference in the overall functionality. From my experience, it seems to work well. =)

  • can I use the sensor with hardware serial on ESP32?

    • bboyho / last month / 1

      Doing a quick test by selecting the ESP32 Dev Module in the Arduino IDE, the ESP32 fails to compile with the fingerprint scanner library. Doing a quick search online, I did not find anyone that had ported the library specifically for the ESP32.

      I suggest trying the method I explained earlier with the dedicated ATmega328P.

    • bboyho / last month / 1

      The fingerprint scanner uses a serial UART. However, the library was written with the software serial library on an ATmega328P. If you follow the packet structure listed in the programming guide from the manufacturer, you could theoretically get it working with the hardware serial on the ESP32. I have not seen it working with the ESP32 since it is a different microcontroller. It may not compile correctly when using a different microcontroller.

      While redundant, it would be easier to have a dedicated ATmega328P communicate with the fingerprint scanner module. Then send a flag or serial packet to the ESP32 to indicate a fingerprint match or fail.

  • Potential n00b question here, but if I pick up the RedBoard Qwiic version, could I just connect this with a single Qwiic-to-Qwiic cable and be done with it?

    • bboyho / last month / 1

      I just got to a computer to compare. Unfortunately, the pinout for the fingerprint scanner do not match the Qwiic pinout so you would not be able to connect the Qwiic-to-Qwiic cable with the RedBoard Qwiic. It just happens that the connectors are the same and you can use the Qwiic-to-breadboard adapter to connect between the scanner and the RedBoard's female headers.

    • Good question. The Qwiic connector is supposed to be for I2C. The fingerprint scanners communicate via a UART port and they happen to have the same type of connector. Hmmm, it might be possible if you adjust the software serial pin definitions for A4 and A5 but you would also need to ensure that the physical pins match the connection. I have not tried that before.

      Try looking at the Qwiic connections and verify it against the fingerprint scanner's pins shown in the hardware overview. I might be able to answer this better if I were at a computer during a normal business day instead my smartphone. ;)

  • Problem in enrolling the finger print in GT-521F32. I am using arduino uno and GT-521f32 with sparkfyn finger print TTL library. The issue is when we are enrolling a finger it will take three finger templates to enroll finger . We want to keep the three finger in same position if we need to enroll a finger,if we put some difference from first finger then the enrollment will be failed and want to restart the enrolling process.Can any one please help me with above issue.

    • bboyho / last month / 1

      Sorry, I just noticed this comment. When enrolling, you need to have three successful enrollments before the sensor is able to save the fingerprint. Make sure that you place your finger in the same position when enrolling for the scanner to properly enroll.

      Try checking the troubleshooting section for more information if you have not already. It may be easier to enroll and verify using the SDK demo software.

  • I'm currently using the Arduino and resistor voltage division because I don't want to buy anything but I'd eventually like to use this with a Raspberry Pi. If I bought the FTDI breakout, would I be able to somehow integrate the fingerprint sensor into a Python program? (Pardon my beginner question :) )

  • Is it possible to change the TX and RX pins on the Arduino? My Arduino has seen better days and its pin 4 is broken.

    • Yes, it is possible. There should be a note in the section called Software Serial w/ Other Microcontrollers. Not all the pins can support change interrupts for a serial Rx pin depending on what Arduino microcontroller is used. However, there are a few other options. It links to the Arduino.cc Software Serial Library.


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