How to check if RA4E2 interrupt timing is correct or not?

Question

Hi, I want to have GTP0 trough interrupt. FSP5.5.0 seems only allowing it if I also enable the crest (cycle end) interrupt, is this behavior correct? 
 Below is fine with both Underflow and overflow interrupts enabled. 
 
 However, if I disable the overflow, I can't have the underflow (trough) interrupt on itself as below. Why? 
 
 Also I want to check if the interrupt timing is correct or not, I try to toggle a couple pins in the interrupt routine, like below. Do I do it correctly? My scope does not indicate that the pins are toggle correctly. timer_trough_callback is the callback for the interrupts.

AZ_Renesas · Answer

Hello, 
 This seems like a bug of FSP configurator. When underflow/through is enabled, another interrupt must be also enabled otherwise it throws an error. I will need to confirm this internally but for now you can keep overflow/crest interrupt enabled. 
 To detect the crest and through events in the callback you can use TIMER_EVENT_CREST and TIMER_EVENT_TROUGH events which are triggered in triangle-wave PWM only.

AZ_Renesas · Answer

I will report it and if it is confirmed as a bug, it will be fixed in future FSP releases. 
 The time from interrupt generation until toggling a pin and actually see it with an oscilloscope is affected by the FSP interrupt handling process and the FSP code that toggles the pin. You have now optimized the latter by writing the register directly, but if you are also interested in minimizing the time of FSP interrupt handling please go through my answer on this thread: 
 community.renesas.com/.../pwm-output-from-i-o-ports