I'm trying to connect a ZFM-60 fingerprint scanner (https://aliexpress.com/item/Free-Shipping-USB-Fingerprint-Sensor-Support-Android-Windows-System-Optical-Fingerprint-Reader-Sensor/32475559052.html?spm=a2g0s.9042311.0.0.WVL3G4) to my RPi 3B. I'm not using the USB-serial converter, because I read that 5V output is enough for this sensor.

I followed this tutorial (https://tutorials-raspberrypi.com/how-to-use-raspberry-pi-fingerprint-sensor-authentication/) to install a library and connect the sensor. Also looked at this question (Unable to integrate Fingerprint sensor in Raspberry Pi2) changing the tty-USB0 into tty-AMA0.

When I run one of the example Python scripts, nothing happens, and the console just shows a blank line until I stop executing the Python script.

The sensor is connected as follows

  • Red -> 5 volt (pin 2)
  • Black -> ground (pin 6)
  • White -> TXD (pin 8)
  • Green -> RXD (pin 10)

Also tried switching white and green, but no effect.

Any ideas on what I'm missing here?

  • 1
    The Pi's GPIO are 3V3 safe only. Feeding 5V into a Pi GPIO will eventually destroy the GPIO and the Pi.
    – joan
    Commented Feb 16, 2018 at 16:24
  • Could you explain then why the GPIO layout mentions some pins with '5V' while this is actually not true?
    – ericrijn
    Commented Feb 19, 2018 at 8:46
  • No, and is there any reason I should? There is an awful lot of incorrect information on the www. Some just mistakes, some malicious.
    – joan
    Commented Feb 19, 2018 at 10:45

2 Answers 2


From the information on the page you should put 3.3v into pin 3, Vin, according to the lower table. There is a problem in that they seem to have multiple definitions of the pins of the device. The demonstration in the video shows it connected to an Arduino UNO rather than a Raspberry Pi.

The translations on AliExpress are not always exact English, and I suspect they are written by people with no knowledge of the subject matter.

To communicate the values from the Raspberry Pi to your computer I would use the built-in wireless (you said you're using a Raspberry Pi 3B).

Have fun!


maybe a little late, but are you using a raspberry pi 3? the pi3 has the gpio serial port named /dev/ttyS0, so instead of using /dev/ttyAMA0 you better use ttyS0, or the new /dev/serial0, the latest firmware asign the correct port (AMA0 on a pi1/2 or S0 on a pi3) to serial0

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