I have 2 external TTL signals I need to time-stamp with 1us precision.  They can switch at a rate  of ~16khz.

What is the best way to go about doing this?  

Can the signals be used directly as interrupts to the Cortex and is there a system clock that can be retrieved?  

Or do I need to run a basic counter at 1Mhz and read out from the status register(s) upon rising edge?  

Or something else?

Thank you!

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Dario
 

When I think of time stamp I think you want to record time of day, hrs:min:sec for

an event occuring every 1/16Khz secs, to a resolution of 1 uS. Or do you just want

to measure period of event ?

For later I would use rising edge of event to enable a counter being clocked at 1 Mhz,

and falling edge to implement a captureof count, which gens an interrupt to read

and reset counter. That way ISR rate is 16 Khz, a resonable rate that won't eat up

a lot of MIPs.

Regards, Dana.

Thanks for the reply...  yes, I mean the former.  

The events are not really periodic... they are random.  But they occur at an average rate of 16Hz. 

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Dario

Taking a 32-bit counter at 1 MHz (which will run for about an hour before overflowing) you may use the capture-properties to get your needed time-stamps. Timing is not as critical because the captured values are storedi in a FIFO and may be read-off in a polling-loop. Since the FIFO is only 4 entries deep it should be considered how many events have to be recorded within which time. 16kHz will give you about 1000 CPU-Cycles to process each event, so if you're not really wasting MIPS it can be done without touching the borders of PSoC design.

Bob

...And if that one-hour-counterr is not sufficent, you may use the period-Interrupt to increment a 32-bit-variable to get a 64-bit time-stamp which will last for ... ahhh... mhhhh... well..... 490,000 years ?

Bob

Authors last post its a 16 Hz rate, not Khz ?

Regards, Dana.

Yes, I saw that, but since it was not correctes explicitly I took the second post as a typo and not the first.

Bob

 Thanks... this works.  Yes, 16khz rate... and it works fine...

Congratulations! We like to meet you here in the fascinating world of PSoCs!

Bob