Generate interrupt signal and measure latency

Dear All,

I’m hoping to use an external PIC microcontroller to generate a interrupt signal to control the sampling sequence of an ADC via the SPI bus on the Gumstix. I’m using the Connex 400xm-bt board.

The interrupt signal from the PIC needs to precede the point in time that the ADC reading will be taken, since it will cause an interrupt in the Gumstix, and that interrupt, however high priority, will take time to service (stacking registers etc.) before the ADC can be told to read. In order to program the timing sequence correctly, I’ll need to measure the time it takes for the interrupt signal to activate the ADC and read the sample on the Gumstix, thereafter estimate how far in advance of the time that it should read we need to output the signal from the PIC.

Can I ask if anyone has tried doing something similar? I’ll greatly appreciate if anyone can advise me on how should I go about simulating this interrupt signal (without having the PIC) using one of the GPIO lines from the gumstix and then measure the latency? I’m really sorry if this sound straightforward to some of you as I’m new to this sort of programming.

Thanks for your help in advance.

Peck