Im having problems on using the GT-521F32 with the NodeMCU 1.0 ESP-12E with the TTL GT521-Fxx library (https://github.com/sparkfun/Fingerprint_Scanner-TTL), the problem is that the code tries to control the nodemcu leds instead of the biometric sensor. If it isnt this i dont know what is.
This is what happens in the serial viewer.
Hi Anode-Cathode,
The GT521-Fxx library was written to work with standard Arduinos (think Uno, Mega, etc.) and uses the SoftwareSerial library. From what I can tell, the standard [Standard Arduino SoftwareSerial Librar does not work with ESP8266-based development boards. As for the LEDs, most likely your NodeMCU has LEDs tied to GPIO 4 and 5 and since the code is attempting to communicate using those pins, you are seeing activity on them.
You could try modifying the examples to use a software serial library that specifically works with ESP8266-based boards like [this. We have not tested this library so I cannot verify it will work but it should help with your issues.](GitHub - plerup/espsoftwareserial: Implementation of the Arduino software serial for ESP8266)](GitHub - PaulStoffregen/SoftwareSerial: SoftwareSerial library used on Teensy)