Hello everyone,
I’m working on a fingerprint-based attendance system using an Arduino UNO and the R307 fingerprint sensor. I have connected all the wires correctly, written the code, and uploaded it without errors. However, the fingerprint sensor is not responding at all — no LED, no serial output, nothing.
My Setup:
- Arduino UNO
- R307 Fingerprint Module
- Wiring (R307 to Arduino UNO):
- VCC → 5V
- GND → GND
- TX → Pin 3
- RX → Pin 2
(Using SoftwareSerial on pins 2 & 3)
- Code:
cpp
CopyEdit
#include <Adafruit_Fingerprint.h>
#include <SoftwareSerial.h>
SoftwareSerial mySerial(2, 3); // RX, TX
Adafruit_Fingerprint finger(&mySerial);
void setup() {
Serial.begin(9600);
while (!Serial); // For Leonardo/Micro
delay(1000);
Serial.println("Fingerprint sensor test");
finger.begin(57600);
if (finger.verifyPassword()) {
Serial.println("Found fingerprint sensor!");
} else {
Serial.println("Did not find fingerprint sensor :(");
while (1) { delay(1); }
}
}
void loop() {
// Nothing for now
}
What I’ve Tried:
- Swapped TX/RX pins (in case of confusion)
- Checked baud rate (57600 is default for R307)
- Verified sensor works by checking the LED (but it doesn't light up)
- Checked power — 5V from UNO is reaching the sensor
- Used external 5V supply (still no result)
Problem:
- The blue LED on the R307 doesn't turn on
- The serial monitor shows: “Did not find fingerprint sensor :(”
Request:
Can anyone suggest how to troubleshoot this issue?
- Is there any way to test if the R307 module is functional?
- Could it be a faulty module, or am I missing something?
Thanks in advance for any guidance.
