Calculating Interrupt latency on Coldfire MCF5475 supported board.

[rlta]

Dear all,

Can anyone please tell me how to find the interrupt latency on my cpu board having MCF5475 and uCLinux as the rtos? I want to use only hardware methods , as i have already calculated the interrupt latendy using software methods. i want to tally both of these figures.

Can any one atleast provide some pointers regarding this matter.

Thanx and regards,

rk.

[mccPaul]

Hi

We have an application using the 5282 which we needed to measure latency on. We have an FPGA that is signalling the CPU with one of the external interrupt lines. It can use IRQ7 or IRQ5. IRQ7 is good for testing as it is not maskable by software. The test involved installing an ISR for IRQ7 that toggled the state of one of our LEDs as it's first instruction.

We set up a logic analyser (but an oscilloscope with two inputs would also work) to measure the time between the change of state on the IRQ7 line and the change of state on the GPIO line controlling the LED.

I have no idea if you can do the same thing with your CPU and with uCLinux but you may try!

Paul.