Example code for Arduino-Check Module Baud Rate
Last revision 2026/01/29
Requirements
-
Hardware
- DFRduino Leonardo (or similar) x 1
- ID809 Capacitive Fingerprint Module x1
- Dupont Wires
-
Software
- Arduino IDE
- Download and install the ID809 Library. (About how to install the library?)
Connection Diagram
Leonardo Connection
UNO Connection

Sample Code 1-Check Module Baud Rate
The module's default baud rate is 115200. You can use the following codes to check its buad rate(the buad rate will not be recovered to default value when the module is power off).
/*!
* @file queryDeviceBPS.ino
* @brief Query device baud rate
* @n Experiment Phenomenon:Query device baud rate, and print from serial port
* @copyright Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
* @licence The MIT License (MIT)
* @author [Eddard]([email protected])
* @version V1.0
* @date 2020-03-19
* @get from https://www.dfrobot.com
* @url https://github.com/DFRobot/DFRobot_ID809
*/
#include <DFRobot_ID809.h>
/*Use software serial when using UNO or NANO*/
#if ((defined ARDUINO_AVR_UNO) || (defined ARDUINO_AVR_NANO))
#include <SoftwareSerial.h>
SoftwareSerial Serial1(2, 3); //RX, TX
#define FPSerial Serial1
#else
#define FPSerial Serial1
#endif
DFRobot_ID809 fingerprint;
uint32_t ID809_BPS[5] = {9600, 19200, 38400, 57600, 115200};
uint8_t i = 0;
void setup(){
/*Init print serial port */
Serial.begin(9600);
/*Test module baud rate */
FPSerial.begin(ID809_BPS[i]);
Serial.print(".");
while(fingerprint.begin(FPSerial) == false){
i++;
FPSerial.begin(ID809_BPS[i]);
Serial.print(".");
}
Serial.println(" ");
}
void loop(){
Serial.print("Module baud rate:");
Serial.println(ID809_BPS[i-1]);
Serial.println("-----------------------------");
delay(1000);
}
Expected Result 1

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