Lpc2000

From what you guys are saying, I think my ISR is too slow!! When I 
feed my system with 10KHz 50% duty, I get 10% error around the 
correct value
In my ISR, I mesure the pulse width by subtracting the last timer 
count from the current timer count.

Any suggestions?
On an average, how many interrupts/second can the LPC handle?
On 10KHz with 8 cpture channels, I get 160,000 interrupts per 
second. Is this possible?

Gus

--- In lpc2000@yahoogroups.com, "philips_apps" <philips_apps@y...> 
wrote:
> Hello Gus,
> 
> LPC2000 samples every CAPx.y input in use at the rate of pclk. It 
> takes two consecutive CAPx.y samples for a transition to be 
detected 
> (i.e. if the current CAPx.y sample is high and the previous sample
> was low, CAPx.y recognizes a rising edge). 
> 
> Assuming no jitter in the processed incoming signal and no jitter 
in 
> the cclk/pclk clock, consecutive readings of the CAPx.y register 
> content should not vary for more than 2 ticks in the worst case. 
The 
> first uncertainty tick comes from the detection of the pulse's
> leading edge, and the second uncertainty tick comes from the 
> detection of the pulse's trailing edge.
> 
> What is the duty cycle of the signal you are processing? Do you 
use 
> the same capture input to detect both rising and falling edge or 
you 
> have two dedicated capture configured pins?
> 
> Regards,
> 
> Philips Apps Team
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "Gus" <gus_is_working@y...> wrote:
> > Hello,
> > 
> > What is the shortest pulse you can mesure on LPC capture module?
> > 
> > I am trying to measure some pulses using the capture hardware on
> LPC 
> > chips. The processor is running at 48Mhz and my capture module 
is 
> > running at 1us/ticks
> > 
> > Connecting a function generator, I can read valid results up to 
> 1Khz. 
> > When I go over 10KHz, the reading is not stable at all! About 10%
> up 
> > and down.
> > 
> > Thanks,
> > 
> > Gus