CHAPTER 3 METHODOLOGY 3.1 Overview The Water Monitoring ...

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Figure 7. Timer 2 Auto Reload Mode (DCEN = 1)(DOWN COUNTING RELOAD VALUE)TOGGLE0FFH0FFHEXF2OSC÷12C/T2 = 0OVERFLOWTH2TL2TF2T2 PINC/T2 = 1CONTROLTR2TIMER 2INTERRUPTRCAP2HRCAP2L(UP COUNTING RELOAD VALUE)COUNTDIRECTION1=UP0=DOWNT2EX PINFigure 8. Timer 2 in Baud Rate Generator ModeTIMER 1 OVERFLOW÷2NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12"0""1"SMOD1OSCT2 PIN÷2TRANSITIONDETECTORC/T2 = 0C/T2 = 1CONTROLTR2TH2RCAP2HTL2RCAP2L"1""1""0""0"÷RCLK16TCLK÷16RxCLOCKTxCLOCKT2EX PINEXF2TIMER 2INTERRUPTCONTROLEXEN212AT89S52
AT89S52Baud Rate GeneratorTimer 2 is selected as the baud rate generator by settingTCLK and/or RCLK in T2CON (Table 2). Note that thebaud rates for transmit and receive can be different if Timer2 is used for the receiver or transmitter and Timer 1 is usedfor the other function. Setting RCLK and/or TCLK putsTimer 2 into its baud rate generator mode, as shown in Figure8.The baud rate generator mode is similar to the auto-reloadmode, in that a rollover in TH2 causes the Timer 2 registersto be reloaded with the 16-bit value in registers RCAP2Hand RCAP2L, which are preset by software.The baud rates in Modes 1 and 3 are determined by Timer2’s overflow rate according to the following equation.Modes 1 and 3 Baud RatesThe Timer can be configured for either timer or counteroperation. In most applications, it is configured for timeroperation (CP/T2 = 0). The timer operation is different forTimer 2 when it is used as a baud rate generator. Normally,as a timer, it increments every machine cycle (at 1/12 theoscillator frequency). As a baud rate generator, however, it=Timer 2 Overflow Rate-----------------------------------------------------------16increments every state time (at 1/2 the oscillator frequency).The baud rate formula is given below.Modes 1 and 3--------------------------------------Baud Rate=Oscillator Frequency-------------------------------------------------------------------------------------32 x [65536-RCAP2H,RCAP2L)]where (RCAP2H, RCAP2L) is the content of RCAP2H andRCAP2L taken as a 16-bit unsigned integer.Timer 2 as a baud rate generator is shown in Figure 8. Thisfigure is valid only if RCLK or TCLK = 1 in T2CON. Notethat a rollover in TH2 does not set TF2 and will not generatean interrupt. Note too, that if EXEN2 is set, a 1-to-0transition in T2EX will set EXF2 but will not cause a reloadfrom (RCAP2H, RCAP2L) to (TH2, TL2). Thus, when Timer2 is in use as a baud rate generator, T2EX can be used asan extra external interrupt.Note that when Timer 2 is running (TR2 = 1) as a timer inthe baud rate generator mode, TH2 or TL2 should not beread from or written to. Under these conditions, the Timer isincremented every state time, and the results of a read orwrite may not be accurate. The RCAP2 registers may beread but should not be written to, because a write mightoverlap a reload and cause write and/or reload errors. Thetimer should be turned off (clear TR2) before accessing theTimer 2 or RCAP2 registers.Figure 9. Timer 2 in Clock-Out ModeOSC÷2TL2(8-BITS)TH2(8-BITS)TR2RCAP2LRCAP2HC/T2 BITP1.0(T2)÷2T2OE (T2MOD.1)TRANSITIONDETECTORP1.1(T2EX)EXF2TIMER 2INTERRUPTEXEN213
Page 1 and 2: CHAPTER 3METHODOLOGY3.1 OverviewThe
Page 3 and 4: 3.2.2 Analog To Digital Conversion
Page 5 and 6: Figure 3.5: Source Code for Convers
Page 7 and 8: 3.2.4 Water Monitoring System Circu
Page 9 and 10: 3.3 Programming.Programming is the
Page 11 and 12: ISP flash programmer in Figure 3.11
Page 13 and 14: The Visual Basic program will start
Page 15 and 16: Distance(cm)ReadingVoltage Trial1 (
Page 17 and 18: 4.2 Signal ConversionA sensor has s
Page 19 and 20: 4.3 User InterfaceBased on Table 4.
Page 21 and 22: Hardware DesignBasically, the const
Page 23 and 24: CHAPTER 5CONCLUSION5.1 SummaryWater
Page 25 and 26: This project can be expanded by usi
Page 27 and 28: APPENDICES41
Page 29 and 30: cjne a,volt,xsamejmp startxsame:mov
Page 31 and 32: xsame19:jnc more19mov dptr,#XVALIDc
Page 33 and 34: etrx:jnb ri,$clr rimov a,sbufretdel
Page 35 and 36: ElseShape8.FillColor = vbWhiteEnd I
Page 37 and 38: Private Sub Timer3_Timer()Label3.Ca
Page 39 and 40: APPENDIX EData Sheet AT89S5253
Page 41 and 42: Features• Compatible with MCS-51
Page 43 and 44: AT89S52Block DiagramP0.0 - P0.7P2.0
Page 45 and 46: AT89S52weakly pulled high. Setting
Page 47 and 48: AT89S52Table 3a. AUXR: Auxiliary Re
Page 49 and 50: AT89S52Watchdog Timer(One-time Enab
Page 51: AT89S52Figure 6. Timer 2 Auto Reloa
Page 55 and 56: AT89S52Oscillator CharacteristicsXT
Page 57 and 58: AT89S52frequency should be less tha
Page 59 and 60: Figure 15. Flash Programming and Ve
Page 61 and 62: AT89S52Table 9. Serial Programming
Page 63 and 64: AT89S52Absolute Maximum Ratings*Ope
Page 65 and 66: AT89S52External Program Memory Read
Page 67 and 68: AT89S52Serial Port Timing: Shift Re
Page 69 and 70: Packaging Information44A, 44-lead,
Page 71 and 72: August 1997SemiconductorADC0802, AD
Page 73 and 74: ADC0802, ADC0803, ADC0804Absolute M
Page 75 and 76: ADC0802, ADC0803, ADC0804Electrical
Page 77 and 78: ADC0802, ADC0803, ADC0804Typical Pe
Page 79 and 80: ADC0802, ADC0803, ADC0804The device
Page 81 and 82: ADC0802, ADC0803, ADC0804V IN ±5VR
Page 83 and 84: ADC0802, ADC0803, ADC0804Figures 19
Page 85 and 86: ADC0802, ADC0803, ADC0804IRQ (4)†

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