Interfacing R307 Optical Fingerprint Scanner with Arduino

Fingerprints are one of the many unique biometric signatures with which we can identify people very accurately. But just by holding someone's hand and staring at their fingers can't be practical [grins]; we're not good at it. But computers are good at recognizing and matching patterns very fast and accurately. But before we can process a fingerprint pattern with a computer, we must "capture" it. There exists many methods to digitize fingerprints; from forensic methods to ultrasound scanning. In this tutorial, we will learn how an Optical Fingerprint Scanner works and how we can interface the R307 fingerprint scanner module to Arduino. R307 is an optical fingerprint scanner module from R30X series produced by a Chinese vendor called Hangzhou Grow Technology Co., Ltd. Other sensors in the series are R300, R301T, R302, R303, R303T, R305, R306, R308, and R311, some of which are capacitive sensors. Despite having different sensing technologies and form-factors, they all share the same interface and control commands. So it is easy to adapt the library you find here for other models as well.

• Power Supply : DC 4.2V-6V
• Current Consumption : ~50mA
• Interface : UART and USB
• Baudrate : (9600 * N) bps, N = 1-12, default is 6
• Image Acquiring Time : <0.5s
• Matching Modes : 1:1, 1:N
• Character File Size : 256 Bytes
• Template Size : 512 Bytes
• Storage Capacity : 1000
• Security Levels : 5
• FAR (False Acceptance Rate) : <0.001%
• FRR (False Recognition Rate) : <0.1%
• Average Searching Time : <1s (1:1000)
• Window Dimensions : 19 * 21 mm
• Working Environment : Temp = -10°C - +40°C, RH = 20%-80%
• Storage Environment : Temp = -40°C - +85°C, RH = <85%
• Outline Dimensions : Split Type, 44.1 * 20 * 23.5 mm

The skin on the palms of our hands have a special pattern called friction ridges that help us grab things effectively without slipping. These patterns consist of ridges and valleys arranged in certain configurations and is unique for each individual. Our finger tips also bear them as you can see from the above image. When a finger comes in contact with a surface, the ridges make strong contact with the surface. When we strongly grab something, the moisture, oil, dirt and dead skin cells on our finger can attach to the surface of the material, leaving an impression we call a fingerprint. Various forensic methods involving the use chemicals are used to extract such fingerprints from crime scenes and are called latent fingerprints. But an optical fingerprint scanner works a bit differently.

An optical fingerprint scanner works based on the principle of Total Internal Reflection (TIR). In an optical fingerprint scanner, a glass prism is used to facilitate TIR. Light from an LED (usually blue color) is allowed to enter through one face of the prism at a certain angle for the TIR to occur. The reflected light exits the prism through the other face where a lens and an image sensor (essentially camera) are placed.

When there's no finger on the prism, the light will be completely reflected off from the surface, producing a plain image in the image sensor. When TIR occurs, a small amount of light leaked to the external medium and it is called the Evanescent Wave. Materials with different refractive indexes (RI) interact with the evanescent wave differently. When we touch a glass surface, only the ridges make good contact with it. The valleys remain separated from the surface by air packets. Our skin and air have different RIs and thus affect the evanescent field differently. This effect is called Frustrated Total Internal Reflection (FTIR). This effect alters the intensities of the internally reflected light and is detected by the image sensor (see this image). The image sensor data is processed to produce a high contrast image which will be the digital version of the fingerprint.

In capacitive sensors, which are more accurate and less bulky, there's no light involved. Instead, an array of capacitive sensors are arranged on the surface of the sensor and allowed to come in contact with the finger. The ridges and air packets affect the capacitive sensors differently. The data from the sensor array can be used to generate a digital image of the fingerprint.

The scanner can be interfaced and powered from both 3.3V and 5V supplies. The working voltage of the scanner controller is always 3.3V. There's a 3.3V regulator on the PCB. The 5V supply you give goes to the input of that regulator, and the 3.3V you supply bypasses the regulator and goes directly to the fingerprint scanner controller.

When you want to power the scanner from 5V and interface with a 5V microcontroller, supply the power to the pins 1 and 6, and disconnect the 3.3V jumper shown in the picture. If you want to supply 3.3V and interface the scanner with a 3.3V microcontroller such as Arduino Due, supply the power to pins 1 and 6 and short the 3.3V jumper. Improper voltages and configurations might damage the controller. So be careful with it.

The pin 6 (Touch Sense Power) is the supply voltage for the finger detection circuit. When a finger is present on the scanner, the output of pin 5 (Touch Sense) will be high. This signal can be used to initiate the scanning of the finger manually. Otherwise the scanner will wait for some time to detect the finger.

The R307 has both USB and UART interfaces. With the USB, you can directly connect the scanner to a computer and communicate with it. A virtual COM port will be created when you connect the scanner to a PC. If you want to interface the scanner with a microcontroller, you can use the UART interface which supports baud rates up to 115200 bps.

The main controller on the PCB is AS606 from a company called Synochip. I don't know how Synochip is related to the company Hangzhou Grow. Whatever that is, the AS606 is a microcontroller with Cordis 5+ RISC cores and has everything needed for a performance controller including a DSP. If you want to know more about the controller check out the datasheet and good luck.

The R307 Manual is the only document to our rescue, and it is ambiguous at many places. The R30X Series Manual has some more information. A schematic is included in the manual.

1. Notepad - This is a 512 bytes of the non-volatile flash memory. It is logically divided into 16 pages with 32 bytes each. Instructions GR_WriteNotepad and GR_ReadNotepad can be used to access this memory. When writing a page, it is taken as a whole and the contents are replaced.

2. Image Buffer - Image buffer is used to store a BMP image of size 256 x 288, each pixel occupying a byte. This buffer is part of the RAM and the contents are lost when power is lost.

3. Character File Buffer - A character file is a processed high contrast image of a fingerprint. Two character files from two consecutive scans are combined to form a template file which is the final version of the fingerprint that is stored in the fingerprint library (not to be confused with the Arduino library. Fingerprint library is the memory used to store up to 1000 fingerprints). The two character file buffers are CharBuffer1 and CharBuffer2 each with size of 512 bytes.

4. Fingerprint Library - This is a section of the flash memory where 1000 fingerprint templates can be stored. Templates are arranged sequentially with numbering from 0 to N-1 (The manual says 0-N) where N is the capacity of the library determined by the size of the flash memory. There are instructions to store, process and delete templates from this memory. They will be explained later.

5. System Configuration Register - This is a 16-bytes long register bank containing operating parameters and status. Except the device address which takes up 4 bytes, rest of the parameters are 2 bytes (a word) in length. The command ReadSysPara can be used to read, and command SetSysPara can be used to write this register bank.

Both UART and USB interfaces use a common serial communication protocol based on a packet format (the manual refers packets as "packages"). All data and commands are to be sent as data packets and all responses from the module will also be packets. So we need to frame data and commands as packets before sending out, and must extract data from response packets. The UART frame format is 10 bit with 1 start bit, 1 stop bit and 8 data bits.

R307 UART frame format

In order make the fingerprint scanner work, we must send instructions or commands in the form of packets. Each instruction is simply a 1-byte code that we must include in the packet. The module responds to each instruction with an acknowledgment packet that describes the result and status of command execution. Each instruction has a set of expected response codes found in the ACK packet that are called confirmation codes. Instructions and their byte codes are grouped according to their functions as shown below,

Following is the list of confirmation codes.

• 0x00 - Command execution complete
• 0x01 - Error when receiving data package
• 0x02 - No finger on the sensor
• 0x03 - Failed to enroll the finger
• 0x04 - Failed to generate character file due to the over-disorderly fingerprint image
• 0x05 - Failed to generate character file due to the over-wet fingerprint image
• 0x06 - Failed to generate character file due to the over-disorderly fingerprint image
• 0x07 - Failed to generate character file due to lack of character point or over-smallness of fingerprint image
• 0x08 - Finger doesn’t match
• 0x09 - Failed to find a matching finger
• 0x0A - Failed to combine the character files
• 0x0B - Addressing PageID is beyond the finger library
• 0x0C - Error when reading template from library or the template is invalid
• 0x0D - Error when uploading template
• 0x0E - Module can’t receive the following data packages
• 0x0F - Error when uploading image
• 0x10 - Failed to delete the template
• 0x11 - Failed to clear finger library
• 0x13 - Wrong password
• 0x15 - Failed to generate the image
• 0x18 - Error when writing flash
• 0x19 - No definition error
• 0x21 - Password not verified
• 0x1A - Invalid register number
• 0x1B - Incorrect configuration of register
• 0x1C - Wrong notepad page number
• 0x1D - Failed to operate the communication port
• 0x41 - No finger on sensor when add fingerprint on second time
• 0x42 - Failed to enroll the finger for second fingerprint scan
• 0x43 - Failed to generate character file due to lack of character point or over-smallness of fingerprint image for second fingerprint scan
• 0x44 - Failed to generate character file due to the over-disorderly fingerprint image for second fingerprint scan
• 0x45 - Duplicate fingerprint
• Others - System reserved

Above is the packet format for verifying password. Address is assumed to be default. We're sending out a command, and so the Packet Identifier has to be 0x07. The Packet Length will be always 7 for this instruction. The Packet Content is split into Instruction Code and Password. Password is 0x6F6F6F6F for our example. If we calculate the Checksum of the bytes, it will be 0x01D7 which is two bytes long.

If the address and password are correct and the packet is correctly formatted, the module will respond with the following acknowledgment packet,

The confirmation code will be 0x00 if our password was correct and 0x13 if it was not.

A Windows application is available to test products in the R30X series. You would find two versions of it if you search online. One is called SFG Demo and the other is SYNO Demo. The latter one found to be better, so I will be demoing that here. You can download both versions in the downloads section.

You can either connect the module directly to the computer via USB or through a USB-UART converter module. In both cases, a virtual COM port will be established in Windows. Then open the SYNO Demo software and use the Open Device button to choose the COM port. You could encounter an issue here. Instead of fetching the list of active COM ports from the OS, the application has a set of predefined COM port numbers. This is from 1-16 in the SYNO Demo software. So if the COM port assigned to your fingerprint module or the USB-UART module is greater than 16, you won't be able to connect. In that case, go to Device Manager and change the COM port number for your module. If an active device was found, its details will be shown in the hardware information window with a success message.

You will come across many inconsistencies and typos while using the software. But that is to expected when the Chinese make English versions of their applications and manuals. Other features of the application are straightforward. A more detailed tutorial on the application can be found here, though for a different version of the module.

The most widely used library for the R30X series modules is the Adafruit Fingerprint Sensor library. It was released 7 years ago, it is hard to understand due to lack of documentation and has limited features. That's when I decided to write one myself. Writing libraries is like an exercise for me.

Since the instruction set and confirmation codes are compatible with many versions of the fingerprint scanner, you could easily modify my library to interface a different type. The code is easy to understand and is shared as an open source project. The library is not complete yet. Many functions are still need to be implemented. But the basic enrolling, searching and matching functions work. All that is working are demonstrated in the example Arduino sketch.

The library consists of a header file R30X_Fingerprint.h and a CPP file R30X_Fingerprint.cpp. The header file will give an overview of the library and it includes all instructions codes, default values, class declarations, parameters and functions declarations.

Since the module uses UART to communicate, you have the choice of choosing serial port you want. With boards like Arduino Uno with single UART, you can use the SoftwareSerial for interfacing the fingerprint module and hardware serial for debugging. Debugging is optional. Currently SoftwareSerial is used for AVR and ESP8266 boards. So when initializing, you must create a SoftwareSerial object and send it to the constructor function. I tested the module with Arduino Due and used the hardware serial.

Library Details

• Library version : 1.0
• Author : Vishnu M Aiea
• Source : https://github.com/vishnumaiea/R30X-Fingerprint-Sensor-Library
• Author's website : www.vishnumaiea.in
• Initial release : IST 07:35 PM, 08-04-2019, Monday
• Last updated : IST 11:44 PM, 08-04-2019, Monday
• License : MIT

Dependencies

1. Arduino.h

2. SoftwareSerial.h

Constants

//-------------------------------------------------------------------------//

//Confirmation codes fingerprint scanner

#define FPS_RESP_OK                      0x00U   //command executed successfully

#define FPS_RESP_RECIEVEERR              0x01U   //packet receive error

#define FPS_RESP_NOFINGER                0x02U   //no finger detected

#define FPS_RESP_ENROLLFAIL              0x03U   //failed to enroll the finger

#define FPS_RESP_OVERDISORDERFAIL        0x04U   //failed to generate character file due to over-disorderly fingerprint image

#define FPS_RESP_OVERWETFAIL             0x05U   //failed to generate character file due to over-wet fingerprint image

#define FPS_RESP_OVERDISORDERFAIL2       0x06U   //failed to generate character file due to over-disorderly fingerprint image

#define FPS_RESP_FEATUREFAIL             0x07U   //failed to generate character file due to over-wet fingerprint image

#define FPS_RESP_DONOTMATCH              0x08U   //fingers do not match

#define FPS_RESP_NOTFOUND                0x09U   //no valid match found

#define FPS_RESP_ENROLLMISMATCH          0x0AU   //failed to combine character files (two character files (images) are used to create a template)

#define FPS_RESP_BADLOCATION             0x0BU   //addressing PageID is beyond the finger library

#define FPS_RESP_INVALIDTEMPLATE         0x0CU   //error when reading template from library or the template is invalid

#define FPS_RESP_TEMPLATEUPLOADFAIL      0x0DU   //error when uploading template

#define FPS_RESP_PACKETACCEPTFAIL        0x0EU   //module can not accept more packets

#define FPS_RESP_IMAGEUPLOADFAIL         0x0FU   //error when uploading image

#define FPS_RESP_TEMPLATEDELETEFAIL      0x10U   //error when deleting template

#define FPS_RESP_DBCLEARFAIL             0x11U   //failed to clear fingerprint library

#define FPS_RESP_WRONGPASSOWRD           0x13U   //wrong password

#define FPS_RESP_IMAGEGENERATEFAIL       0x15U   //fail to generate the image due to lackness of valid primary image

#define FPS_RESP_FLASHWRITEERR           0x18U   //error when writing flash

#define FPS_RESP_NODEFINITIONERR         0x19U   //no definition error

#define FPS_RESP_INVALIDREG              0x1AU   //invalid register number

#define FPS_RESP_INCORRECTCONFIG         0x1BU   //incorrect configuration of register

#define FPS_RESP_WRONGNOTEPADPAGE        0x1CU   //wrong notepad page number

#define FPS_RESP_COMPORTERR              0x1DU   //failed to operate the communication port

#define FPS_RESP_INVALIDREG              0x1AU   //invalid register number

#define FPS_RESP_SECONDSCANNOFINGER      0x41U   //secondary fingerprint scan failed due to no finger

#define FPS_RESP_SECONDENROLLFAIL        0x42U   //failed to enroll second fingerprint

#define FPS_RESP_SECONDFEATUREFAIL       0x43U   //failed to generate character file due to lack of enough features

#define FPS_RESP_SECONDOVERDISORDERFAIL  0x44U   //failed to generate character file due to over-disorderliness

#define FPS_RESP_DUPLICATEFINGERPRINT    0x45U   //duplicate fingerprint

//-------------------------------------------------------------------------//

//Received packet verification status codes from host device

#define FPS_RX_OK                        0x00U  //when the response is correct

#define FPS_RX_BADPACKET                 0x01U  //if the packet received from FPS is badly formatted

#define FPS_RX_WRONG_RESPONSE            0x02U  //unexpected response

#define FPS_RX_TIMEOUT                   0x03U  //when no response was received

//-------------------------------------------------------------------------//

//Packet IDs

#define FPS_ID_STARTCODE              0xEF01U

#define FPS_ID_STARTCODEHIGH          0xEFU

#define FPS_ID_STARTCODELOW           0x01U

#define FPS_ID_COMMANDPACKET          0x01U

#define FPS_ID_DATAPACKET             0x02U

#define FPS_ID_ACKPACKET              0x07U

#define FPS_ID_ENDDATAPACKET          0x08U

//-------------------------------------------------------------------------//

//Command codes

#define FPS_CMD_GENIMAGE              0x01U    //collect finger image

#define FPS_CMD_IMAGE2TZ              0x02U    //generate char file from image

#define FPS_CMD_MATCHTEMPLATES        0x03U    //match two fingerprints precisely

#define FPS_CMD_SEARCHLIBRARY         0x04U    //search the fingerprint library

#define FPS_CMD_REGMODEL              0x05U    //combine character files and generate template

#define FPS_CMD_STORETEMPLATE         0x06U    //store template

#define FPS_CMD_LOADTEMPLATE          0x07U    //read/load template

#define FPS_CMD_UPLOADTEMPLATE        0x08U    //upload template

#define FPS_CMD_DOWNLOADTEMPLATE      0x09U    //download template

#define FPS_CMD_DOWNLOADIMAGE         0x0AU    //upload image

#define FPS_CMD_UPLOADIMAGE           0x0BU    //upload image to the sensor

#define FPS_CMD_DELETETEMPLATE        0x0CU    //delete template

#define FPS_CMD_CLEARLIBRARY          0x0DU    //clear fingerprint library

#define FPS_CMD_SETSYSPARA            0x0EU    //set system configuration register

#define FPS_CMD_READSYSPARA           0x0FU    //read system configuration register

#define FPS_CMD_SETPASSWORD           0x12U    //set device password

#define FPS_CMD_VERIFYPASSWORD        0x13U    //verify device password

#define FPS_CMD_GETRANDOMCODE         0x14U    //get random code from device

#define FPS_CMD_SETDEVICEADDRESS      0x15U    //set 4 byte device address

#define FPS_CMD_PORTCONTROL           0x17U    //enable or disable comm port

#define FPS_CMD_WRITENOTEPAD          0x18U    //write to device notepad

#define FPS_CMD_READNOTEPAD           0x19U    //read from device notepad

#define FPS_CMD_HISPEEDSEARCH         0x1BU    //highspeed search of fingerprint

#define FPS_CMD_TEMPLATECOUNT         0x1DU    //read total template count

#define FPS_CMD_GETANDRANGESEARCH     0x32U    //read total template count

#define FPS_CMD_GETANDFULLSEARCH      0x34U    //read total template count

#define FPS_DEFAULT_TIMEOUT                 2000  //UART reading timeout in milliseconds

#define FPS_DEFAULT_BAUDRATE                57600 //9600*6

#define FPS_DEFAULT_RX_DATA_LENGTH          64    //the max length of data in a received packet

#define FPS_DEFAULT_SECURITY_LEVEL          3     //the threshold at which the fingerprints will be matched

#define FPS_DEFAULT_SERIAL_BUFFER_LENGTH    300   //length of the buffer used to read the serial data

#define FPS_DEFAULT_PASSWORD                0xFFFFFFFF

#define FPS_DEFAULT_ADDRESS                 0xFFFFFFFF

#define FPS_BAD_VALUE                       0x1FU //some bad value or parameter was delivered

#define FPS_DEBUG           //uncomment this line to enable debug info to be printed

#define debugPort Serial    //select the hardware serial port for debugging

Classes

1. R30X_Fingerprint

Member Variables

private:

//common parameters

uint32_t devicePasswordL; //32-bit single value version of password (L = long)

uint32_t deviceAddressL;  //module's address

uint16_t startCodeL; //packet start marker

uint8_t devicePassword[4]; //array version of password

uint8_t deviceAddress[4]; //device address as an array

uint8_t startCode[2]; //packet start marker

uint32_t deviceBaudrate;  //UART speed

uint8_t securityLevel;  //threshold level for fingerprint matching

uint16_t dataPacketLength; //the max length of data in packet. can be 32, 64, 128 or 256

//transmit packet parameters

uint8_t txPacketType; //type of packet

uint16_t txPacketLengthL; //length of packet (Data + Checksum)

uint8_t txInstructionCode;  //instruction to be sent to FPS

uint16_t txPacketChecksumL; //checksum long value

uint8_t txPacketLength[2];  //packet length as an array

uint8_t *txDataBuffer; //packet data buffer

uint16_t txDataBufferLength; //length of actual data in a packet

uint8_t txPacketChecksum[2];  //packet checksum as an array

//receive packet parameters

uint8_t rxPacketType; //type of packet

uint16_t rxPacketLengthL; //packet length long

uint8_t rxConfirmationCode; //the return codes from the FPS

uint16_t rxPacketChecksumL; //packet checksum long

uint8_t rxPacketLength[2];  //packet length as an array

uint8_t *rxDataBuffer; //packet data buffer

uint32_t rxDataBufferLength;  //the length of the data only. this doesn't include instruction or confirmation code

uint8_t rxPacketChecksum[2];  //packet checksum as array

uint16_t fingerId; //location of fingerprint in the library

uint16_t matchScore;  //the match score of comparison of two fingerprints

uint16_t templateCount; //total number of fingerprint templates in the library

uint16_t statusRegister;  //contents of the FPS status register

private:

Stream *mySerial; //stream class is used to facilitate communication

SoftwareSerial *swSerial; //for those devices with only one hardware UART

HardwareSerial *hwSerial; //for those devices with multiple hardware UARTs

Member Functions

R30X_Fingerprint (HardwareSerial *hs, uint32_t password = FPS_DEFAULT_PASSWORD, uint32_t address = FPS_DEFAULT_ADDRESS);  //constructor for hardware serial

R30X_Fingerprint (SoftwareSerial *ss, uint32_t password = FPS_DEFAULT_PASSWORD, uint32_t address = FPS_DEFAULT_ADDRESS);  //constructor for software serial

void begin (uint32_t baud); //initializes the communication port

void resetParameters (void); //initialize and reset and all parameters

uint8_t verifyPassword (uint32_t password = FPS_DEFAULT_PASSWORD); //verify the user supplied password

uint8_t setPassword (uint32_t password);  //set FPS password

uint8_t setAddress (uint32_t address = FPS_DEFAULT_ADDRESS);  //set FPS address

uint8_t setBaudrate (uint32_t baud);  //set UART baudrate, default is 57000

uint8_t setSecurityLevel (uint8_t level); //set the threshold for fingerprint matching

uint8_t setDataLength (uint16_t length); //set the max length of data in a packet

uint8_t portControl (uint8_t value);  //turn the comm port on or off

uint8_t sendPacket (uint8_t type, uint8_t command, uint8_t* data = NULL, uint16_t dataLength = 0); //assemble and send packets to FPS

uint8_t receivePacket (uint32_t timeout=FPS_DEFAULT_TIMEOUT); //receive packet from FPS

uint8_t readSysPara (void); //read FPS system configuration

uint8_t captureAndRangeSearch (uint16_t captureTimeout, uint16_t startId, uint16_t count); //scan a finger and search a range of locations

uint8_t captureAndFullSearch (void);  //scan a finger and search the entire library

uint8_t generateImage (void); //scan a finger, generate an image and store it in the buffer

uint8_t downloadImage (void); //download image from sensor

uint8_t uploadImage (uint8_t* dataBuffer);  //upload image to sensor

uint8_t generateCharacter (uint8_t bufferId); //generate character file from image

uint8_t generateTemplate (void);  //combine the two character files and generate a single template

uint8_t downloadCharacter (uint8_t bufferId); //download character file stored in one of the two buffers

uint8_t uploadCharacter (uint8_t bufferId, uint8_t* dataBuffer);  //upload character files to one of the two buffers

uint8_t saveTemplate (uint8_t bufferId, uint16_t location);  //store the template in the buffer to a location in the library

uint8_t loadTemplate (uint8_t bufferId, uint16_t location); //load a template from library to one of the buffers

uint8_t deleteTemplate (uint16_t startLocation, uint16_t count);  //delete a set of templates from library

uint8_t clearLibrary (void);  //delete all templates from library

uint8_t matchTemplates (void);  //match the templates stored in the two character buffers

uint8_t searchLibrary (uint8_t bufferId, uint16_t startLocation, uint16_t count); //search the library for a template stored in the buffer

uint8_t getTemplateCount (void);  //get the total no. of templates in the library

1. R30X_Fingerprint (HardwareSerial *hs, uint32_t password = FPS_DEFAULT_PASSWORD, uint32_t address = FPS_DEFAULT_ADDRESS);

2. R30X_Fingerprint (SoftwareSerial *ss, uint32_t password = FPS_DEFAULT_PASSWORD, uint32_t address = FPS_DEFAULT_ADDRESS);

3. void begin (uint32_t baud);

4. void resetParameters (void);

5. uint8_t verifyPassword (uint32_t password = FPS_DEFAULT_PASSWORD);

6. uint8_t setPassword (uint32_t password);

7. uint8_t setAddress (uint32_t address = FPS_DEFAULT_ADDRESS);

8. uint8_t setBaudrate (uint32_t baud);

9. uint8_t setSecurityLevel (uint8_t level);

10. uint8_t setDataLength (uint16_t length);

11. uint8_t portControl (uint8_t value);

12. uint8_t sendPacket (uint8_t type, uint8_t command, uint8_t* data = NULL, uint16_t dataLength = 0);

13. uint8_t receivePacket (uint32_t timeout=FPS_DEFAULT_TIMEOUT);

14. uint8_t readSysPara (void);

15. uint8_t captureAndRangeSearch (uint16_t captureTimeout, uint16_t startId, uint16_t count);

16. uint8_t captureAndFullSearch (void);

17. uint8_t generateImage (void);

18. uint8_t downloadImage (void);

19. uint8_t generateCharacter (uint8_t bufferId);

20. uint8_t generateTemplate (void);

21. uint8_t downloadCharacter (uint8_t bufferId);

22. uint8_t uploadCharacter (uint8_t bufferId, uint8_t* dataBuffer);

23. uint8_t saveTemplate (uint8_t bufferId, uint16_t location);

24. uint8_t loadTemplate (uint8_t bufferId, uint16_t location);

25. uint8_t deleteTemplate (uint16_t startLocation, uint16_t count);

26. uint8_t clearLibrary (void);

27. uint8_t matchTemplates (void);

28. uint8_t searchLibrary (uint8_t bufferId, uint16_t startLocation, uint16_t count);

29. uint8_t getTemplateCount (void);

I wrote this code for Arduino Due which has 4 hardware serial ports. I'm using first serial port Serial for debugging and Serial1 for fingerprint scanner interface. I'm using the default password and address of 0xFFFFFFFF. Three of these parameters are passed to the constructor. You must use the password and address of your module if it was ever changed.

In the setup() function, we first initialize the debugging port and the fingerprint module. fps is the object we're using. Then we have to verify the password before doing anything else. Otherwise the scanner will refuse to execute our commands. Optionally you may set a new address, or verify the existing address.

In the loop() function, we periodically check the serial port for incoming data. When data is available, it is read as a string and it is checked for valid commands and parameters. If it's a valid command, rest of the parameters are extracted from the string in order as firstParam, secondParam and thirdParam. Then the parameters are sent to corresponding function to execute. Once the command is executed, the results are stored in the variables and we wait for new instructions. Following is the list of the available commands.

• clrlib - clear library
• tmpcnt - get templates count
• readsys - read system parameters
• setdatlen <data length> - set data length
• capranser <timeout> <start location> <quantity> - capture and range search library for fingerprint
• capfulser - capture and full search the library for fingerprint
• enroll <location> - enroll new fingerprint
• verpwd <password> - verify 4 byte device password
• setpwd <password> - set new 4 byte device password
• setaddr <address> - set new 4 byte device address
• setbaud <baudrate> - set the baudrate
• setseclvl <level> - set security level
• genimg - generate image
• genchar <buffer id> - generate character file from image
• gentmp - generate template from character buffers
• savtmp <buffer id> <location> - save template to library from buffer
• lodtmp <buffer id> <location> - load template from library to buffer
• deltmp <start location> <quantity> - delete one or more templates from library
• mattmp - precisely match two templates available on buffers
• serlib <buffer id> <start location> <quantity> - search library for content on the buffer

It took me a very long time to develop the library for this fingerprint scanner module and a good amount of time to write this documentation. I hope you will my tutorial useful. If you found any error with documentation or code, however small it is, feel free to tell me about it. Your questions are welcome.