Erwin, I don't know your exact situation but have you thought about using a counter/timer card. There is hardware out there that can do this for you. Both ISA and PCI. Check out computerboards.com they have many different boards available. Specifically, for ISA go to http://www.measurementcomputing.com/cbicatalog/directory.asp?dept%5Fid=218&t op%5Fid=22&dept%5Fname=ISA&mscssid=2JWEM4R1H0SR2JEQ000JU4JKRUXG953A . If you have the signal going to a large cascade counter you can have count values on the order of 80 bits. You can also have the signal connected to a preset down counter that will cause an interrupt when it reaches zero. Thus you don't have to poll. Furthermore, you don't have to get an interrupt with each pulse.
I hope this helps, Rich -----Original Message----- From: Erwin Triepels [mailto:[EMAIL PROTECTED]] Sent: Friday, October 26, 2001 12:32 AM To: [EMAIL PROTECTED] Subject: [rtl] Optimizing real time performance? Dear people of RTL-mailing list, We at NBG-Industrial (Location Nederweert, Netherlands) are trying to sample/count a TTL-signal with a frequency of 200 kHz (or as high as posssible). We use a PIO-24 card (ISA-based) to generate an interrupt at each pulse. The interrupthandler in RTlinux is used to increase a counter. In a seperate thread, which starts up every second, the time is measured and the frequency is calculated. The precision of the frequency was measured while linux itself was heavily loaded (compiling a kernel). 20 kHz is the highest frequency which can be measured without a deviation. 25 kHz is still measured reasonably well(a deviation of -6 Hz once in the 200 times). But frequencies above 30 kHz are measured with a deviation of minimal 10 Hz almost every measurement (which is too large). Is there a way too improve this performance? For instance optimizing core.c/core.o? Yours sincerely, Erwin Triepels The code is added as an attachmant -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
