Re: [avrdude-dev] USART1

[Lou]

On 27 Apr 2003 at 17:23, 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?

Summing up the two answers, from Brian and Joerg (working in reset state, 
using UART0), what I'd add is just that the first programming phase takes 
over everything just once (or twice, if you're unlucky?), anyway only during 
development.

Instead of a jumper I'd think about employing a single resistor (say 1.. 4.7 
kOhm), in series to the transmit-data-from-serial-port line: the MOSI line 
from the outside would a have a "precedence" over it, and if the programmer 
has a buffer (as a generic '244) can safely drive that.

This would help you *a lot* in avoiding mis-configuration of jumpers, in any 
production/test environment.

Lou