Generating a clock in C

[GeekWizard]

Hello all,

I want to generate a clock signal in 'C/C++' and then send it directly through the parallel port to the outside device.

Can anyone guide me how to go about this please.

Many Thanks.

 

[abhikohli]

you can use infinite loop, (nano)sleep (platform dependent) and finally outport/outb to parallel port (Address 0x378, mostly, on PC)
If you are using linux this can help you:

https://www.tldp.org/HOWTO/IO-Port-Programming.html

 

[CMOS]

The following code will generate a square wave of approximately 500 Hz on D0 line (Pin 2) of parallel port having address 0x378. For delays smaller than 1mS...i think you need to use assembly language routine for your delay.

#include <stdio.h>
#include <conio.h>

void main(void)
{
	char key;
	while((key = toupper(getch())) != 'Q')
	{
		outputrb(0x378, 0x01);
		delay(1);
		outportb(0x378, 0x00);
		delay(1);
	}
}

 

[jhbbunch]

it won't be an accurate clock since the OS is multitasking and can suspend your task for up to milliseconds, intensive HD access can cause delays and so on. Use the Win API calls QueryPerformanceCounter and QueryPerformanceFrequency to establish a timebase and frequency. I used it to drive 2 stepper motors with good results.

 

[CMOS]

I too agree with jhbbunch. I have used QueryperformanceCounter and QueryperformanceFrequency APIs in VB with very good results.