How can I have an I/O pin Pulse / Toggle etc. when Start of Frame messages are received. It must be low latency.
may be you set/clear a pin with "CyU3PGpioSimpleSetValue" (creates a impulse length of almost a micro second just a bit faster). That is the fastes way which supports the FX3 SDK.
But if you like to read in the message via an interrupt and set then a pin. Then the latency is about 30 to 40 micro seconds for the interrupt and additional the pin toggle.
30 to 40 uS is too much uncertainty. I need more of a hardware interrupt based solution with 10's of nanoseconds uncertainty.
Then I do not know how you can do this with the FX3 SDK and the threadx operating system on FX3.
May be if you open a technical support case the engineers from cypress can help you or can tell you what is possible or not.