I always use a full-echo protocol for communication between a PC and a PIC:
PC sends a char, and must wait until it has received the echo before
sending the next char. PIC sends only on request, a special char is
reserved to ask to PIC to send its next char. Note that the PIC must send
something, so when it has nothing it must send a dummy char. When the PC
has not received a response for 1 second it is allowed to retry (happends
almost never).
Wouter

----------
> From: Keelan Lightfoot <keelan@MAIL.BZZZZZZ.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: UARTless & Interruptless RS232 flow control
> Date: Sunday, July 02, 2000 05:13
>
> I am trying to implement rs-232 communication on a UARTless pic (16F84 --
> surprise, surprise :). I have the code created to send and recieve data
via
> any pin, and that works fine, the problem now is flow control... It's for
an
> LCD serializer, and I need the PC to stop talking when I'm busy working
with
> the LCD module... I can twiddle with CTS, but apparently, the 16550 UART
> (and derivitaves thereof) sends 8 bytes even after the CTS line has been
> cleared... (the 8250 is apparently not guilty of this crime)
>
> My serial code is of the non-interrupt-driven variety.
>
> How can I make this work? I have tried different thoughts like using a
small
> FIFO, etc., but none of these seem to want to work... I'm stuck... Is it
> something I'm not thinking about, or is it not possible, or what?
>
> I don't wanna use the 'solution' of telling my computer that it's 16550
is
> actually an 8250, I wanna have this work with any computer...
>
> Any suggestions?
>
> Thanks in advance :)
> - Keelan Lightfoot

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