Capacitive Fingerprint Scanner/Sensor on ESP8266

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#1

Hello!
I recently purchased Grove - Capacitive Fingerprint Scanner/Sensor.
Like that one: link

I tried connecting it many ways to the ESP board.
VCC-VCC, RX-D2, TX-D3, GND-GND,
VCC-VCC, RX-D3, TX-D2, GND-GND,
VCC-VCC, RX-D5, TX-D6, GND-GND.
VCC-VCC, RX-D6, TX-D5, GND-GND.
I got this output: Wait for response of finger-print sensor 5 seconds infinitely.
Of course after every connection change I updated code to match pins.

VCC-VCC, TX-RX, RX-TX, GND-GND:
I wasn’t able to upload program to the ESP board.

I also tried both 5V and 3.3V.
Sensor is emitting blue light but does not give any response to ESP8266.
I think, that I connected it wrongly.

Also: I modified the connector, because I wasn’t able to connect it to pins on ESP8266. Please see image below.

sensor
sensor4032×3024 803 KB

I’m using this library: link

How should I connect it? Please help me.

#2

That’s the right way to do it. Make sure the hardware is properly connected.

#3

Ok, I made some more connection changes.
Now its behaviour is somewhat weird.
I uploaded this code (slightly modified example, matches my pins): https://pastebin.com/2nZSxLkC

After boot, it displays message to register fingerprint (on serial monitor).
But it does not allow me to do that, because it immediately prints “Register ok!”.
I didn’t even place my finger on sensor, but it prints this success message.
…and after that it lovely crash with stack print + reboot.

Please check this output: https://pastebin.com/sqDWr8bk
Ah and it does not turn on green light.

#4

Hello! Are you there? :yum:

#5

Yes, I’ve been there, but I can only give you some advice, maybe you can compare the normal signal with the logic analyzer.

#6

Sadly, I don’t own logic analyzer.
But I found this demo file on SeeedDocument GitHub. It contained EXE program, which allowed me to test my fingerprint sensor.

So, I uploaded this program to my ESP8266, and basically it just forwards UART to computer. And after that I was able to use my sensor with demo on Windows. This means, that my hardware connections are 100% good.

In my opinion, the problem is in library provided by Seeed. I think that it wasn’t tested on ESP8266.

I’m thinking about setting up COM proxy on Windows, to check how SYDemo.exe interacts with the device (and then program ESP to reply with previously recorded commands). But this solution is time-consuming and I hope that there are better ways to solve this issue.

#7

Thread can be closed.
I made my own library, by utilizing my COM Proxy.

1 Like
#8

@enter, will you please share the library on git? I’m having a similar problem

#9

Please share your lib. I have bought 3 of these from mouser. and because I bought them from mouser, seeed is giving me the finger on support. I have had the same problem and have been fighting for almost a year.