How to use at the best FPIN in SEROUT/SERIN.

[wirecut]

Hi,

using as reference the diagram on page 358 of the manual Ver.3.1 PDS 2005-06-16 I would better understand the use of flow control pin FPIN.
My sender is a 16F877 and my receiver is a 18F2550.
What I have achieved by following the instructions in the manual works fine, but I would understand more.

The statement that I used are:

Serin PORTA.0 \ PORTA.1, 16390, [Status] '38400 'is the maximum allowable speed for 877 20 MHz clock
SerOut PORTA.5 \ PORTA.3, 16390, [Status]

I noticed that when is excecuted the statement SERIN, FPIN changed from low to high, remain high throughout the sending of bytes then lowers

for 3.5 U.S. and then back up to about 620 uS, then go back down and stay down until the next SERIN.

I understand that PFIN is high during the reception of the byte, and then changes its state at the end of the byte reception, but I do not

understand why then returns high for 620 uS.

Someone could explain it?

Ciao

Leo