Good morning,
I want to interface the GT-511C3 fingerprint sensor to Arduino.
I used two resistors 2.2kohms and 100koms.
The blink example is working. However, the enrol example is not working.
Can you assist please
Please draw and upload a schematic of your project, exactly as you have wired it. Please also upload the code you're testing with.
Can you reply please
Ok, here we go:
The schematic you've posted is incomplete: 
The code you're testing with was not attached:
Referring to the schematic you did post in #3: I assume that the thought behind the resistor divider is that it should have translated the 5V output voltage from the Arduino's pin 5 to a safe level of around 3.3V for the fingerprint sensor. However, given the resistor values drawn, the signal level on the fingerprint sensor's RX pin would work out as around 4.9V - which probably far exceeds its ratings. Start by replacing the 2.2k resistor with e.g. 47k. That would get you closer.
You've not included the connection between the TX pin of the sensor to pin 4 (?) of your Arduino. The schematic does not show the Arduino. It doesn't make explicit where the power for the sensor comes from. Although for these expects I could make an educated guess based on the photo you posted earlier.
As to what code you're testing with, you'll really have to enlighten me.
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