Output pin control during deep sleep

[tuftec]

I have a need to pulse an output pin every 2 seconds while in deepsleep (using LoPy4 and FiPy). Is there an easy way to do this?
My application is battery powered and sleeps for a good part of the time.

I understand that I might have to write some code to work with the ULP. Can I do this from within MicroPython? Maybe sending the code (pre-compiled) to the ULP from within MicroPython?

Is there a good reference on how to work with the ULP? What tools should I use to write code for this? I currently use Atom and Pymakr.

Any suggestions would be greatly appreciated.

Peter.