PPORT 1.1 :

PPort is designed to control the PCs parallel port.

Click here to download   PPORT 1.1.zip (239kb)

Usage :

- Clicking the data , state and control tabs at the top, you can choose the port you want to send or receive data.

- Change bits ,with a '0' first state value, by clicking (you can see the decimal equivalent of the binary number.) and click the 'send to' button.The number at the bottom of the window will change.This shows the received data from the active port.

Also you can test the data at the port using a multimeter.For example if you send the value '2' (forming the bits 00000010) to the data port , you will see 5 volts (logic 1) on the pin 3 and the other pins of the data port ( 2,4,5,6,7,8,9) will be 0 volt (logic 0) .

Note : On some computers these values can be different like 3.40 volts for logic 1.The important thing is to understand the value as logic 1.

An application :

Take a led and connect its anode to parallel port's second pin with a small valued resistor if necessary.And connect the cathode to one of chassis pins of the parallel port.( 18 to 25 ).Send '1' (00000001) to data port

with the program.Led will be lighted.

- The lists on the program can be useful when we want to send datas in rows with a time interval.

An application :

Make these connections then make program pins decimal '1' and click '+' button.Repeat this for the numbers 2,4,8,16,32,64,128 then click to 'GO' button.Leds will be lighted in rows with an interval 1 sec.You can adjust time by changing the value at the interval.

- To change or remove a value from the list , you have to choose it first.If the value you choosed is a data , change bits to change it.To remove it click on the ' - ' button.

If the value is an interval , change the number on the interval.

Click somewhere on the form (program window) to deselect.

- Reset button clears the lists.

- Right click on the form to see the shortcuts.

- Watch button shows an other form.This form reads the port states in every 1 m sec.So that u can follow the changes.An example , connect a pin of state port to a chassis pin (18 to 25).You will see that the value '120' is changed.You can try it for control port.As you know data port is not an input port.

Control Port :

- Either you can send data to control port or you can read from it.

Pins of this port are 1,14,16,17.Pin 17 is the MSB.

(MSB :Most Significant Bit , LSB :Less Significant Bit)

Pins 1,14,17 are inverted inside the port .For example , if you send '1' (by forming bits as '1000' ) the MSB pin (pin 17) will be 0 volt , because it is inverted.

bits ( 3 -- 2 -- 1 -- 0 )

pins(1*- 14*- 16 - 17*) ( * :inverted bits.)

- You can check start reading to read data every 1 milisec.

State Port :

- State port is used to get input only.Pins of this port are :

MSB 11*- 10 - 12 - 13 - 15 - .. - .. - .. LSB.

This port has an interesting structure.Let me try to explain it to you:

Some computers may be different but as you see on the left , you always read '120' value from this port...

pin 11 is called as BUSY and this is the 7th (MSB) bit ,which is inverted inside the port.

Pin 10 is the 6th ,pin 12 is the 5th, pin 13 is the 4th and pin 15 is the 3th bit.In addition :

bits ( 7 - 6 - 5 - 4 - 3 )

pins ( 11*-10-12-13-15)

All pins of this port are at 5 volts and the 2th,1th and the LSB are logic 0.But we can't use them.

So program reads the value 0 1 1 1 1 0 0 0 (decimal 120).

In addition , we can control only 5 bits of this port.I suggest you to set and test this circuit :

(you can use BC238 transistor.)

Pin 2 is the LSB of the data port.Busy is 5 volts.Click to watch button and send '1' (forming the bits 00000001) to data port to make the pin 2 logic 1.With this,transistor makes the busy 0 volt by carrying it to chassis.

So that the value at the state port will be '248' (11111000).Because busy is inverted inside the port.

Try this circuit for the pins 10 , 12 , 13 , 15.This will help you to understand the behaviour of the state port.

Last , i want to give the fundemental codes of my program,that i designed with delphi 5 :

implementation

{$R *.DFM}

procedure PortOut(IOport:word; Value:byte); assembler;

asm

xchg ax,dx

out dx,al

end;

function PortIn(IOport:word):byte; assembler;

asm

mov dx,ax

in al,dx

end;

Write this procedure and function under implementation.So that you can call them from anywhere you want in your designs.Example :

procedure TForm1.Button1Click(sender: TObject) ;

Begin

portout(888,2); // 888 is the decimal adress of data port.889 and 890 are

edit1.text:=inttostr(portin(888));// the adresses of state and control port.

end;

I'm waiting for your suggestions...

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