Passing Mailbox messages between ARM and PRU

@Chris_Grey, @BarryBeagle, et. al:

I was just reviewing my old R5F gpio toggle experiment post. In that post, Chris stated that he was working on the BBAI-64 PRUs but hadn’t yet gotten an IO to toggle. I wanted to check back in with you guys: Have you been able to use the BBAI64 PRU_ICSSG to control IO?

Thanks and Best regards,
Fred Eckert