AVR-Chat

Im using Atmega8 in my projects, and I have a question about,  what to 
do with pins not used? in the case of AREF I read that I must conect to 
Vcc by a resistor, but in the other pins dont know what to do.


Thanks in advance.

jdelgadillo66 wrote:
> Im using Atmega8 in my projects, and I have a question about,  what to 
> do with pins not used? in the case of AREF I read that I must conect to 
> Vcc by a resistor, but in the other pins dont know what to do.
> 
> 
> Thanks in advance.
> 
   This simplest thing to do is to set them as outputs.  You should not 
leave inputs floating, that can cause all kinds of problems.

DLC


-- 
---------------------------------------
Dennis Clark    TTT Enterprises
---------------------------------------

Dennis Clark wrote:
> jdelgadillo66 wrote:
> 
>>Im using Atmega8 in my projects, and I have a question about,  what to 
>>do with pins not used? in the case of AREF I read that I must conect to 
>>Vcc by a resistor, but in the other pins dont know what to do.
>>
>>
>>Thanks in advance.
>>
> 
>    This simplest thing to do is to set them as outputs.  You should not 
> leave inputs floating, that can cause all kinds of problems.
> 
> DLC

Go ahead and put a resistor to ground or Vcc anyway.  I normally tie the 
free end of the resistors to Vcc unless the databook says otherwise. 
100K ~ 1 meg should do nicely, and will not load down the pins if you 
decide to use them later.

-- 
erikc
--
"The kind of man who wants the government to adopt and enforce his
ideas is always the kind of man whose ideas are idiotic."
    -- H. L. Mencken

On Fri, 12 Aug 2005 15:14:33 -0600 you wrote:

>Dennis Clark wrote:
>> jdelgadillo66 wrote:
>> 
>>>Im using Atmega8 in my projects, and I have a question about,  what to 
>>>do with pins not used? in the case of AREF I read that I must conect to 
>>>Vcc by a resistor, but in the other pins dont know what to do.
>>>

Here's the recommendation from the mega128 datasheet:

"If some pins are unused, it is recommended to ensure that these pins have a defined level. Even
though most of the digital inputs are disabled in the deep sleep modes as
described above, floating inputs should be avoided to reduce current consumption in all
other modes where the digital inputs are enabled (Reset, Active mode and Idle mode).
The simplest method to ensure a defined level of an unused pin, is to enable the internal
pull-up. In this case, the pull-up will be disabled during reset. If low power consumption
during reset is important, it is recommended to use an external pull-up or pull-down.
Connecting unused pins directly to VCC or GND is not recommended, since this may
cause excessive currents if the pin is accidentally configured as an output."
--
Ralph Hilton
http://www.ralphhilton.org
C-Meter: http://www.cmeter.org
FZAOINT http://www.fzaoint.net