We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you a podcast all about Citrix Workspace, moving to the cloud, and analytics & intelligence. Episode 2 coming soon!Listen Now

x

C Language question

ghausheer
ghausheer asked
on
Medium Priority
208 Views
Last Modified: 2012-05-04
I am trying to read data from the parallel port at precise intervals (The fastest needed interval is 43 microseconds)
There are also a few steps which need to be done after reading the data.  To do this I beleive I need a very accurate timer, and the standard timer on the PC is only accurate to 54 miliseconds.  We have tried reading data from the 8253 external timer, but have not had much luck with this.  Does anyone have any ideas?
Comment
Watch Question

Commented:
Talking directly to the 8253 should give you the resolution you crave. Check out this web site for some samples and instructions on dealing directly with the timer -
http://www.strangecreations.com/strange/library/hardware/pit.txt

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
rbr

Commented:
If you use an AT you can use Function 83h of Interrupt 15h.
This function sets a flag at Bit number 7 after a period of time.
AH:= 83h
ES:= Segment Adress of the flag.
BX:= Offset Adress of the flag.
CX:= High Word of Microseconds you want
DX:= Low Word of Microseconds you want.

Or if you want to wait for some microseconds use function 86h of the same interrupt.
AH:=86h
CX:= High word of microseconds to wait for.
DX:= Low Word of microseconds to wait for.



Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.