3.5.2. Temperature Detection - Parallel Port

In this experiment we will show you how easy to display temperature from a sensor by using command mode WR only. Build up a circuit as shown in picture bellow. As you seen in picture, this ADC will receive voltages from 0 to 1 volt, so the Vref must be 0.5 volt.

Delphi Programming ( Download File exp352.zip )

a. Puts 1 Timer Components, 2 Edit Component and label on Form, as shown in picture bellow.

b.Click on Timer1 component to insert with the program as shown bellow

procedure TADC.Timer1Timer(Sender: TObject);
var dataA,dataB,data:byte;temperature:real;
begin
 asm
  mov dx,$378      {Port Data}
  mov al,00000010b {Start Conversion Pulse WR=1}
  out dx,al
  ;
  mov dx,$378      {Port Data}
  mov al,00000000b {Start Conversion Pulse WR=0}
  out dx,al
  ;
  mov dx,$378      {Port Data}
  mov al,00000010b {Start Conversion Pulse WR=1}
  out dx,al
  ;
  mov dx,$378      {Port Data}
  mov al,00000010b {Drive A/B=0,to select D0-D3,from MUX74157}
  out dx,al
  ;
  mov dx,$379      {Port Status}
  in al,dx         {get data D0-D3 from Mux}
  and al,11110000b {masking bit D0-D3 for Port Status}
  xor al,10000000b {Bit 7 Inverting}
  mov dataA,al     {saving data Reg AL to variable Data}
  ;
  ;
  mov dx,$378      {Port Data}
  mov al,00000011b {Drive A/B=1,to select D0-D3,from MUX74157}
  out dx,al
  ;
  mov dx,$379      {Port Status}
  in al,dx         {get data D0-D3 from Mux}
  and al,11110000b {masking bit D0-D3 for Port Status}
  xor al,10000000b {Bit 7 Inverting}
  mov dataB,al     {saving data Reg AL to variable Data}
  ;
 end;
 data:=( DataA DIV 16 ) + DataB;
 temperature:=data*5/255;
 Edit1.text:=inttostr(data);
 Edit2.text:=floattostr(temperature);
end;

c. To run the program, you can hits F9 or RUN menu, and then you will see a picture as shown bellow, and try to simulate the program by sensing a temperature.

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Delphi

Lesson 1
Delphi Programming
1.1. IDE Delphi
1.2. Component

Lesson 2
Printer Port / LPT
1.1.Basic
1.2.Address
1.3.Port Register
1.4.8 Bit Data Input
1.5.Test Circuitry
1.6.Assignment

Lesson 3
Printer Port / LPT
Experiments
3.1.LED
3.2.Swicht
3.3.Motor Stepper
3.4.DAC
3.5.ADC
3.6.Graph Display

Lesson 4
Serial Port
4.1.Basic
4.2.Hardware
4.3.Port Register

Lesson 5
Serial Port Experiments
5.1.LED
5.2.Stepper Motor
5.3.Swicht
5.4.ADC

Lesson 6
Game Port
Joy Stick
6.1. Basic
6.2. Experiments