How to use the debug for solution engine?

I use the solution engine on the SH4-7750R!
Now I have the BSP code .
now I want to boot for flash on the baordï¹—
the screen stop :
Neutrino 2.1 SolutionEngine IPL
Hit ‘d’ to download update Neutrino image
Press any other key to boot from flash

I want to use the LED to debug the question!
Who can supply me the idea?
And supplu me the a circuit diagram for the solution engine!

thanks :unamused: