Locker System Using Android’s Fingerprint





The basic idea of this project is to simulate a locking/unlocking mechanism to the users, which they can lock/unlock using their android’s fingerprint mechanism.


Components required

  • Wiz750SR
  • DC motor
  • Arduino Uno

Arduino UNO: It is the decision maker. It decides which button is pressed in the app or what command is given to the device from the app.
Cloud Broker: Our broker in this project is online to control the transfer of messages via MQTT.
WIZ750SR/S2E: It is a protocol converter that transmits data sent by serial equipment (e.g. Arduino) as TCP/IP data and converts the TCP/IP data received through the network(e.g. Mobile App) back into serial data to the serial equipment. Hence, it receives data from the Android app installed on a mobile and transmits this data serially to the Arduino.
WIZ750SR-EVB: This is the evaluation board for the WIZ750SR. The S2E can be fixed on top of this board.
DC Motor: It is a motor that rotates the lock.
L298N motor driver: It is a motor driver that helps to lock/unlock at ease.
9V Batteries
Circuit Setup

  • First, we power on both the boards (S2E & Arduino Uno).
  • Then, we connect the Ethernet cable to the S2E.
  •  From here, we connect the RS232 to the S2E, and connect the other end to the Arduino using the jumper wires by connecting the Rx, Tx of the RS232 to the Pin 10, 11 and the GND pin to the GND of the Arduino.
  •  Now, we connect the Arduino board with L298N motor driver , by connecting the Pin 6,7 of the Arduino to the motor driver and 5v of Arduino to the motor driver.
  • Finally, we connect the DC motor to the L298N motor driver with Input 1,2 of the motor driver, and also we connect the 9V battery to the motor driver.
  • Take a female to female RS232 cable and plug it into the RS232 port of the S2E. The other end of the RS232 cable needs to be connected to the Arduino. In the RS232 female head, pin 2 acts as the transmitter and pin 3 acts as the receiver. These pins are connected to the Arduino digital pins 11 and 10 respectively. The ground of the RS232 (pin 5) is connected to the ground of the Arduino.

Setting Up Android Studio

Setting Up the Broker

  • We used the cloudMQTT online broker. Just make an account on cloudMQTT and you are good to go. Make a note of the host name, port number, username and password. These credentials would be used in android application as well as WIZ7500P(S2E).
  • Upload the Code to S2E
  • S2E board fixed on top of evaluation board
  • First and foremost, set the pin on the evaluation board of the S2E to BOOT mode and press reset. i.e. move the center switch (highlighted using a black box in the bottom left hand corner of the above image) to the right before starting the next step.
  • Then, download the W7500P ISP tool from the following link : the S2E to a laptop via its microUSB port to figure which COM number is assigned to it using “Device Manager”. The USB to UART driver can be downloaded from
  • If it’s not installed on your device. In the image below it can be seen that COM6 has been assigned to the S2E.
  • Then hit “Refresh” button in the ISP tool and select the appropriate port number from the drop down list. The baud rate should be fixed at 9600.
  • Then hit “Open” button in the ISP tool. If successful, one can see the result – “Serial Open Complete” in the left bottom corner.
  • The S2E uses ARM Cortex-M0 architecture. In order to program the S2E we’ll have to use the ARM compiler that can be accessed using: When you login into the compiler select the board as “WIZwiki- W7500P”.

Uploading the Code to Arduino
The Arduino is the mastermind of the project. It receives the signal from the IR transmitter and recognizes the command given to the device and so the execution can be made accordingly. IR receiver is connected to the arduino which receives the signal and further through the broker it is sent to the MQTT terminal that gives the output (for reference) and the device would work according to the command given.
In order to use the Arduino we must first install its IDE. The Arduino IDE is easy to use as well as open source and can be easily downloaded from the official Arduino website. Once the IDE is installed, the next step would be to select the board. The board can be selected by going through the “Tools” option as depicted in the image below:
ISP Tool
Select Board
Once the board is selected. The port at which the Arduino will be available for serial communication needs to be selected as depicted below:
Select COM Port
The next step would be to upload the “Arduino_code”(available in the code section of this project’s description) into the IDE. Once that is done the code can be compiled and uploaded onto the board by clicking the tick mark and arrow button respectively.
Compile and Upload sketch to board
Final Result
We can use CoolTerm to test out the serial port, which can be downloaded from CoolTerm will enable us to read all the messages sent to the COM port.
When the message is sent via the app, the response output from the Arduino can be seen on the CoolTerm terminal.






Tags: 201810, Wiz310SR, Serial to Ethernet, fingerprint, W7500P


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