Category Archives: Programming

Driver xDRV.sys is driver developed by Иванов Д. Ð’.(www.pcports.ru) and is capable to work(read write) with any PC port under windows NT, 2000, XP. But main advantage of this driver is that it can catch and handle LPT port interrupts (in this case LPT1 with address 0×378 with IRQ 07).

Program part of xDRV

Lets see how this driver can be put in action. First of all download packed archive with driver and library with functions.

xDRV.sys <13.2kB>

In this package you will find driver xDRV.sys, dynamical library xDRV.dll, statical library xDRV.lib, which may be needed while compiling project with statical connection of dll and header file with function prototype description which can control driver. Let see the functions:

bool xDRV_OpenDriver();

Driver xDRV.sys is dynamically loadable. For loading this driver and initializing this function is used. If driver is loaded successfully, then function returns TRUE otherwise FALSE. This function has to be called one time at the beginning. If function returned FALSE then try to restart computer might be xDRV.sys already has been loaded to the memory and function xDRV_StopDriver() wasn’t used. Driver and library has to be placed in same directory where project files are.

void xDRV_StopDriver();

As it was mentioned – this function is important. It has to be called at the end of program work. If not – driver will stay loaded in to memory and will take over interrupts. And during second load program will throw an error.

void xDRV_Write(unsigned short PortAdr, unsigned char PortValue);

This function is used to write one byte of data(PortValue) to port(PortAdr). For instance in order to make all data-lines high in port you should write: xDRV_Write(0×378, 255) ;

unsigned char xDRV_Read(unsigned short PortAdr);

This function obviously is used for reading byte from port(PortAdr).

void xDRV_InitInterput(void(*FunAdr)(void* p), void* param);

This function is most exiting in this driver. This function is the main reason why this driver was created. Driver in order to be able announce about interrupt it is important to give to interrupt function special function address with strict structure. Then when interrupt occur this function will be called. Function should look like:

void fn_name(void *var_name);

Second xDRV_InitInterput() parameter can be any, which will be passed to special function when it is called.

To make things more clear there are tow there are two ready projects with all driver functions used. One project is written in C/C++ language in Microsoft Visual C++ 6.0 environment (WinAPI) and another MFC ( MICROSOFT FOUNDATION CLASS LIBRARY):

WinAPI Test (xDRV.sys) <53.1kB>

MFC Test (xDRV.sys) <44.9kB>

Hardware part

Now its time to prepare hardware part that xDRV.sys could work properly. Go to Control Panel->System->Hardware->Device Manager->Ports(COM and LPT)->Printer Port(LPT1)->Properties. In tab Port Parameters select “Use any interrupt assigned to the port”.

Then in port header set pin 15 to “0”(STATUS register – ERROR) connecting this pin to ground. Now you can start program that uses xDRV.sys. You can try to write and read from port. But lets see how interrupts work. As we said 15 pin should be connected to ground. Driver registers interrupts from 10^th pin of LPT port (ACK). Every time this pin goes LOW the interrupt will be registered.

If ERROR line wasn’t connected to ground, then only one interrupt could be registered, but in DATA and CONTROL register would start chaos which would last for about one minute. The reason of this is native port driver which tries to ping to printer which it thinks should be connected to port. But there is no any printer then this actions is useless. So put 15 pin to ground and don’t bother. Of course we lose one control line, but interrupt ability compensates this.

Source: http://www.pcports.ru

Another way of controlling LPT port under Windows 2000 and XP using Delphi language. In this case library inpout32.dll is used which allows controlling LPT port registers.

Ready project for Borland Delphi 7.0 you can download here: Project Files<187.5kB>

And now how to do this from beginning. Start Borland Delphi 7.0 and make simple form where you can enter Data to be sent to port, Port Address, buttons for writing to and reading from port.

If you are familiar with building forms this should be ease task.

OK now lets start programming. First of all wee need somehow to include inpout32.dll in to the project. For this Delphi has several ways, but lets stay to the easiest one when library is in same directory, where project is. Then in header in section uses we have to place function prototypes Out32 and Inp32 with special compiler directive external, saying where to find this finction.

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

 function Inp32(PortAdr: word): byte; stdcall; external 'inpout32.dll';
 function Out32(PortAdr: word; Data: byte): byte; stdcall; external 'inpout32.dll';

Then lets go to the button methods. For this double click on button in form and you will be directed to editor. Firs o all lets work with wiring to port function. Place data to the variables Port and Data from text fields convert them from text to numerical data and then call function Out32() with these parameters.

procedure TForm1.Button1Click(Sender: TObject);
var
    Port: word;
    Data: Byte;
begin
    Data:= StrToInt(Edit1.Text);
    Port:= StrToInt(Edit2.Text);
    Out32(Port, Data);
end;

Same way we have to deal with reading. Port Address is taken from Port Address text field. This is where data will be read from. Then call function Inp32() with port number and output received data to the window.

procedure TForm1.Button2Click(Sender: TObject);
var
    Port: word;
    Data: Byte;
begin
    Port:= StrToInt(Edit3.Text);
    Data:= Inp32(Port);
    MessageDlg('Value: '+ IntToStr(Data), mtInformation, [mbOK], 0);
end;

Compile program and start. Try to write to DATA register of LPT port number 0. For this port address will be 888(or hexadecimal $378). Press button and if you have some tester connected to LPT you will se the results. Same way you can work with reading.

Source: www.pcports.ru

There are a lot of Radio amateurs that want to control external devices using computer standard ports. One of them is COM poert. Everybody wants things to be ease as people doing electronics are more hardware people not software. COM port is more often used than LPT because COM port is more resistive to bigger loads and there is less chances of failing.

So if you know Visual Basic a little bit then this shouldn’t be very hard to use MSComm Control component which is located in Project->Components. You should check check box MSComm Control. Later you have to add this control to form and write some code for it.

Main difficulty with this is that you have to follow RS232 protocol. This is why it is better to use microcontrollers that have built in USART interface. Of course MSComm component allows to read and control single COM pins and this way to control any external devices without using RS232 protocol.

One good example is popular programming software PonyProg (which is programmed in other language than VB, but principals are same). You can see various supported circuits that PonyProg supports and you can see that Rx(2) and Tx(3) signals aren’t used at all. All data transfer is done via CTS(8), DSR(6), DTR(4), RTS(7) (in some places Tx(3) is used).

In order to read pin state of port it is enough to send unipolar positive signals without converting TTL-RS232. Of course this doesn’t comply with RS232 standard but this way works perfectly. But this is only recommended to hobby circuits. Professional hardware should have conversion.

So we can read three pins of COM port: CD, CTS, DSR. Command reading CTS(8) would look as follows:

If MSComm1.CTSHolding = False Then

or

If MSComm1.CTSHolding = True Then

With this command we can read weather logical 0 or 1 is on pin CTS.

COM port pins DTR and RTS are capable to output (+12V) and (-12V) and this way to light a LED or turn on Relay or other device. For instance output for pin RTS command:

MSComm1.RTSEnable = False (+12v on 7 pin)

MSComm1.RTSEnable = True (-12v on 7 pin)

Thats it. Using these commands it is possible to program simple data transfer or complicated protocols for instance I2C, SPI, MicroWire and so on. One of good examples is DS1621 pc thermometer, developed by Alberto Ricci. He programmed I2C protocol for data transfer between DS1621 thermometer.

You can construct simple circuit in few minutes (you can assemble it directly on DB9 header).

Then you can start program Com_device to see how program reacts on button press and toggles LED using exactly same commands that we described above.

If your device requires pulse signal this also non difficult task but in this case you should know RS232 protocol a little bit:

Then you can start program Com_device to see how program reacts on button press and toggles LED using exactly same commands that we described above.

If your device requires pulse signal this also non difficult task but in this case you should know RS232 protocol a little bit:

Changing number of impulses for “0” and “1” we can change impulse width in ine byte limits with one bit step. So we can send numbers FF, FE, FC, F8, F0, E0, C0, 80, 00 to port to get all awailabe interval of impulse widths. Picture above is F0.

In order to send to port such signal we need to send following command:

MSComm1.Output = “symbol or string”

Using this command you can send any ASCII character to port. So if you want to send F0 (decimal 240), then use following:

MSComm1.Output = Chr(240)

This way we can generate 8 level PWM and control motor speed or LED brightness – just signal has to be amplified, because maximal current driven from port is 25mA.

Port settings can be changed with command

MSComm1.Settings = “1200,N,8,1″

this way we can change baud rate parity, number of bits and number of stop bits.

Source: http://www.schemz.narod.ru

This is simple routine of sending and reading of byte from LPT1 port under Windows XP.

LPT port has four types of pins:

• 8 output pins accessed via the DATA Port
• 5 input pins (one inverted) accessed via the STATUS Port
• 4 output pins (three inverted) accessed via the CONTROL Port
• The remaining 8 pins are grounded

Now we are interested in Data pins.

Set up driver according to post: Acces LPT and COM ports easily under windows NT-2000-XP. I have written and compiled example under DEV-CPP tool-set, which you can download from http://www.bloodshed.net/.

Start New console project

Create new cpp file and save it to project directory. Also copy porttalk_IOCTL.h and pt_ioctl.c files to project directory. These files you will find in the package portalk22.zip.

Test program:

Compile this program and run it. You should see results like this:

Now it is time to connect your microcontroller and start experimenting. Good luck.

Test routine project files for DEV-CPP are here:LPT1 Sample Project