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Micro controller based DAQ
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Micro controller based DAQ

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  • 1. DATA ACQUISITION SYSTEM USING AT89C51 PREM KUMAR M-TECH (PED) REG NO-1611110018
  • 2. INTRODUCTION The main objective of this project is to developthe data acquisition system. In this project AT89c51 isused to develop the data acquisition system
  • 3. WHAT IS DAQ?  Data acquisition (DAQ) is the process of measuring an electrical or physical phenomenon such as voltage, current, temperature, pressure, or sound with a computer.  DAQ systems either measure a physical parameter or take a specific action (sound an alarm, turn on a light, etc.) based on the data received.
  • 4. DAQ SYSTEM A DAQ system consists of sensors, DAQmeasurement hardware, and a computer withprogrammable software sensor DAQ DEVICE COMPUTER DRIVER
  • 5. BLOCK EXPLANATION First the sensor measures the physical quantity or electrical quantity like temperature, pressure, voltage or current. DAQ device which converts measured analog signal into digital signal. And it is also interfaced with PC. We can control the driver circuit by computer through data acquisition system.
  • 6. INTERFACING DIAGRAM
  • 7. PIN DESCRIPTIONCONNECTEDTO ADC TOSELECTSENSORCONNECTEDTO DRIVERCIRCUIT CONNECTED TO MAX 232 CONNECTED TO ADC
  • 8. ANALOG TO DIGITAL CONVERTER ADC 0808 is 8 bit analog to digital converter, which uses successive approximation type conversion. Key specifications:  Resolution 8 Bits  Total Unadjusted Error ±½ LSB and ±1 LSB  Single Supply 5 VDC  Conversion Time 100 μs
  • 9. MAX 232 The RS232 is not compatible with 89c51,we need a voltage converter to convert the RS232’s signals to TTL voltage levels that will be acceptable to the 89c51’s TxD and RxD pins. The MAX232 converts from RS232 voltage levels to TTL voltage levels, and vice versa.one advantage of the MAX232 chip is that we can use same power supply(+5V) for controller and MAX232.
  • 10. PROGRAM Start : MOV P1,#00H LCALL initserial LCALL latch LCALL start_conv LCALL wait LCALL get MOV A,P2 MOV R6,A LCALL send_read SJMP Start
  • 11. PROGRAM CONT….delay :MOV R4,#80Hhere : MOV R5,#30Hagain : DJNZ R5,again DJNZ R4,here RETinitserial : MOV TMOD,#20H MOV TH1,#FDH MOV SCON,#50H SETB TR1 SETB EA SETB ES RET
  • 12. PROGRAM CONT….start_conv : LCALL delay CLR P3.3 LCALL delay SETB P3.3 RETwait : JB P3.4,wait RETget : LCALL delay CLR P3.5 LCALL delay SETB P3.5 RET
  • 13. PROGRAM CONT….send_char : MOV SBUF,R6next : JNB TI,next CLR TI RETsend_read : LCALL send_char MOV A,# “,” LCALL send_char RETlatch : CLR P3.6 LCALL delay SETB P3.6 RET
  • 14. CONCLUSION Thus, the data acquisition system usingATMEL89c51 microcontroller and ADC0808 isdesigned. Also, proved it is more flexible as programcan be changed according to requirement repeatedly.