Re: [avrdude-dev] USART1

[Brian Dean]

On Sun, Apr 27, 2003 at 05:23:47PM -0700, Erick Castillo wrote:

> I can see how disabling the external circuitry with jumpers might work,
> but what about the software side. Suppose I program PORTE or USART1 so
> that there is continous activity through those lines. Will I have to
> explicitly disable the UART in order to program it using those same lines
> or can I simply start the download?

No you don't have to do anything special regarding programming because
during programming, the processor is held at reset (/RESET pulled low)
the entire time, so your program is not running then.  Just ensure
that you use a programmer that has a buffer (most commercial
programmers do).  The buffer is to make sure that the programming
hardware does not interfere with your application circuit when it is
running and allows you to keep the programming cable attached (useful
for initial debugging).

> I guess my major concern here is, should I use the PORTE USART pins only
> for serial programming or is there an easy solution for using both. The

The solution is two-fold - ensure that your application does not
interfere with programming (how you achieve this is application
dependent).  And use a programmer that doesn't interfere with your
application (usually any programmer with a "buffer" chip will meet
that criteria).

Cheers,
-Brian
-- 
Brian Dean
address@hidden
http://www.bsdhome.com/
http://www.bdmicro.com/