AVR-Chat

I'm a bit tight on pin count, and would like to use the 3 ISP pins (MISO/MOSI/SCL) for LEDs. My plan is to tie the LEDs high, and then through resistors down to these pins.

I've "tested" this on an STK500 buy attaching the LED 10pin connector to the appropriate ports and have had no troubles.

I'm just looking for the "net wisdom" as to whether this is an acceptable practice.

 - jim

James,

> I'm just looking for the "net wisdom" as to whether this is an acceptable
practice.

Yeah, I do it all the time, looks kinda cool during programming too.
One peice of advice, include a short delay after power up, but before you
setup the IO pins.
in CV-AVr I do something like this ;-

void main(void)
{
delay_ms(200);
setup_io();
// rest of my code goes here.

This ensures that I'm not making the IO pins go high or low whilst the
programmer is jiggling the Reset line.
you could use a shorter delay, but I'm just paranoid.

Paul

--- In AVR-Chat@yahoogroups.com, "Paul Maddox" <P.Maddox@s...> wrote:

> Yeah, I do it all the time ...

For beginners, maybe we should point out that during programming the 
programmer has to drive the LED currents, which it may not actually 
be designed to do. So, success may depend on which programmer is in 
use and the value of the LED current.

For example, this would not work with my JTAG interface. There are 
resistors in series with all the inputs and outputs intended to guard 
against connection to the wrong header, backwards connection and 
other accidents. I don't have an ISP programmer, but if I did it 
would also have current limiting resistors.

Graham.

I want to use a atmega64 as a TWI slave device, but
the only example I found is for IAR EWAAVR 2.28a
compiler:

http://www.atmel.com/dyn/resources/prod_documents/doc2565.pdf
http://www.atmel.com/dyn/resources/prod_documents/AVR311.zip

Where can I find an example of twi slave for WinAVR
compiler?

Jose


	

	
		
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