Print Based Security System Personal Safes are revolutionary locking storage cases that open with just the touch of your finger. These products are designed as “access denial” secure storage for medications, jewelry, weapons, documents, and other valuable or potentially harmful items. These utilize fingerprint recognition technology to allow access to only those whose fingerprints you choose. It contains all the necessary electronics to allow you to store, delete, and verify fingerprints with just the touch of a button.
Stored fingerprints are retained even in the event of complete power failure or battery drain. These eliminates the need for keeping track of keys or remembering a combination password, or PIN. It can only be opened when an authorized user is present, since there are no keys or combinations to be copied or stolen, or locks that can be picked. keeping track of keys or remembering a combination password, or PIN. It can only be opened when an authorized user is present, since there are no keys or combinations to be copied or stolen, or locks that can be picked.
DS1820 Based High Precision Temperature Indicator This project is an High precision digital thermometer which indicates the temperature on the seven segment display. It has an resolution of 0. 06deg. The 1 wire temperature sensor IC from Maxim semiconductors is used as the sensor. The DS18S20 Digital Thermometer provides 9–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points.
The DS18S20 communicates over a 1-wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor.It has an operating temperature range of –55°C to +125°C. In this project the negative temperatures are not taken so that it will display the temperature from 0deg to 99. 9deg. Sending Data From The PC to a Microcontroller In this article we are going to learn how to send data to a microcontroller and make the microcontroller respond to the data. For simplicity we are just going to send data to turn on and off an LED which is connected at port P2.
0. So lets start off with designing a communications protocol. From VB we will send an ASCII 255, as a synch byte, and the on/off state (0 or 1).The microcontroller will wait for two (2) bytes of data. After these two bytes of data are received, it will then either switch on/off the LED Visual Basic at PC side To get started open Visual Basic. Start a new Standard EXE.
Next go to the Project | Components… menu Check the Microsoft Comm control 6. 0.
Click OK. Next double-click on the yellow phone in the toolbar to add the MSComm control to your form. Now add two option buttons from the tool bar name as “opton” and “optoff”, change the caption to ON and OFF for both buttopns.Now add a command button named cmdsend from the tool bar, and chage the caption to “SEND” On To The Code Now that the form is set up and ready to go, we need to start adding our code to the project. The user will select a pin state from option button, and then click cmdSend to send the data to the microcontroller. So first of all we need to set up the MSComm control, and select one of the pin states to start with. So lets add the following code to our form..
. Private Sub Form_Load() On Error Resume Next ‘use comm port 1 MSComm1. CommPort = 1 9600 baud, no parity, 8 data bits, 1 stop bit MSComm1. Settings = “9600,N,8,1” ‘ Disable DTR MSComm1.
DTREnable = False ‘open the port MSComm1. PortOpen = True End Sub Now we just need to add the code to send the data. When the user presses cmdSend, we need to do three things. Get the pin state…
Send the data… Now lets put it all together and send the data when we press the cmdSend button…
Private Sub cmdsend_Click() Dim LED As Long ‘ Get LED State If opton. Value = True Then LED = 0 Else LED = 1 End If ‘ Send Out Data MSComm1. Output = Chr$(255) ;amp; Chr$(LED)End Sub So we sent out the synch byte (255),followed by the LED state. Finally we need to close the comm port when the VB project unloads so… Private Sub Form_Unload(Cancel As Integer) MSComm1.
PortOpen = False ‘Close the COMM port End Sub That’s all at the PC side Microcontroller Side Program the MIcrocontroller with the following code ORG 00H ; Reset MOV TMOD,#20H ;enable timer1, mode 2 (auto reload) MOV TH1,#0FDH ;9600 Baud rate MOV SCON,#50H ;8 bit, 1 stop bit, REN enabled SETB TR1 HERE:JNB RI,HERE ;wait for character to come in MOV A,SBUF ;get data in ACJNE A,#0FFH,DOWN ;chk if the char is synch byte ie. offh or 255 ;if not jump to clear RI CLR RI ;get ready to get next byte WAIT:JNB RI,WAIT ;wait for character to come in MOV A,SBUF ;get data in A CJNE A,#00H,NXT ;chk if the char is 0 CLR P2. 0 ;switch on LED SJMP DOWN ;jump to clear RI NXT:CJNE A,#01H,DOWN ;chk if the char is 1 SETB P2. 0 ;switch off LED DOWN:CLR RI ;get ready to get next byte SJMP HERE ;keep getting the data Now run the VB project, select either ON or OFF, and press send. You should see the LED turn ON when you send a ON command, and turn OFF when you send a OFF command.