[avr-chat] Flow control with Butterfly

[Pertti Kellomäki]

I am writing a data logging application using the Butterfly
as the target hardware. I can talk to the  Butterfly using a
terminal, but if I try to talk to it with a Python program,
some characters get lost.

I have used the application shipped with the Butterfly as
a starting point, so when receiving from the uart my program
also continually polls the pins connected to the joystic. The
LCD driver is also working at the same time.

Now my question is: should I need flow control at all, and
if so, what should it be? My hunch is that at 9600 baud the
Butterfly should not have any problems keeping up, but
I don't have any idea of e.g. the overhead of the LCD driver.

The easiest way out for me is to implement a simple minded
protocol, where the Butterfly echoes everything back, and
the PC side reads each character before sending the next
one. This is not very elegant, though, so I am thinking of
interrupt-driven receiving from the uart.

I could implement hardware flow control, but I an unsure
whether all PC serial ports respect rts/cts signals. It also
seems that I would neet to generate them by software on
the Butterfly.

Any thoughts?
--
Pertti