post details Interfacing Finger Print Sensor 89C51, 89C51 89S51, 89S52 Microcontrollers | Biomedical Attendance System
Finger Print Sensor, Bio Medical Attendance System
Develop BIo Medical Attendance System 89C51-52 And 89S51 89S52
The finger print sensor is used to identify the person from its finger or thumb impressions interface print sensor with finger 89C51 Microcontroller. The finger print is a very versatile sensor that can read and store the fingerprint in its own internal storage flash memory for its future purpose. Special purpose to use this device as a Biomedical Attendance System using fingerprint sensor. It store the information in the memory by using various functions. It contains normally three functions to read and store the information about the person in the form of ID. When we interface fingerprint sensor with 89C51 Microcontoller  then it can be used a compled system. By making pin simply low and pressing onboard three switches to function with. The result is always in the two form either it is an error or in OK and it is indicated by onboard LED. Then the information is passed from serial port to the serial port of 8051 microcontrollers to the computer to further processing of the received data.
The received and return bytes are  valid ID of the person or error code. The response or result byte is only  single byte at 9600 bits per second thus making complete finger print sensor with 89S51 Microcontroller unit working in practical manner. Every finger print sensor has indicating LEDs and switches already on board, always ready to work when you get it. 
Features Of Finger Print Sensors
  • Easy To Interface With Microcontrollers
  • Status LEDs showing results
  • Function Switches to control the device
  • Get data in Single byte response
  • Works at 5V TTL
  • Serial Port Transmission UART 9600bps
  • Quick Response 
Inputs and Outputs of Sensor
Input Fucntions: There are two methods of triggering function on finger print sensors
1.  Onboard inbuilt switch: Add, Empty or Search.
2.  Make pin low from external microcontroller for 5ms as per function required to be executed.
Outputs(Response): Two ways to monitor output response after a function is executed
1.  Onboard LEDs: ERROR or OK
2.  Read byte after executing function
Types of function
There are namely three functions you can call for the fingerprint sensor. We will see each in brief. Add(Enroll) Function: Adds a fingerprint to database and return a byte of newly added ID. Return values are from 0x00 to 0xFE. In case of error like no finger placed, return code is 0xFF. Here 0xFF means error executing function Search Function: When a finger is put and search funtion is called, it returns a matching ID if found in its existing memory. Return values are from 0x00 to 0xFE. In case of error like no finger placed, return code is 0xFF.  Fnger print sensor with 89S52 Microcontroller Here 0xFF means error executing function. Empty Function: When you wish to empty all fingerprint data stored on sensor you can use this function. After executing this function, you will get 0xCC as OK or 0xFF in case of error.