AVR-Chat

Hi, James

    The OSCCAL calibration works really very well if you can guarante the 
operating temperature.. If temperature varies too much it will not be enough 
for reliable communications.. What makes the Tiny13 even more interesting is 
that the voltage reference is much better than in the Atmega8, for example 
and the price tag is great for simple applications. It is small but for some 
applications sparing a pin is possible..

    The only other way that I can see to make reliable serial comms at some 
speed with it is if we calibrate the timing using the timing of the start 
bit from the other serial device.. That works great but just under some 
protocols and it also makes software much more complicated..

    If the external oscillator can be made cheaply enough it is a great 
option for many applications... The sub-dollar price tag with a nice AD 
converter and voltage reference that works makes the Tiny13 a very, very 
nice beast to be explored....

Best regards,
Alexandre Guimaraes

----- Original Message ----- 
From: "James Hatley" <james.hatley@comcast.net>
To: <AVR-Chat@yahoogroups.com>
Sent: Monday, July 04, 2005 11:47 PM
Subject: Re: [AVR-Chat] External oscillator for the Tiny13.


> Hello,
>
> Reviewing your original note ... you want to do serial communication and 
> you
> think you need a crystal oscillator to clock the mpu.
>
> It seems to me that there is no reason that the internal oscillator and a
> bit-bang serial comm solution won't work just fine. These type of routines
> have been through here a number of times and I'm sure that there are a
> number of examples around. The internal oscillator, at least in the Atmel
> mpus that I've used, can be tweeked with OSCCAL to get pretty close, like 
> 2%
> or better. That should be quite sufficient to do serial communication.
>
> That part, the ATtiny13 doesn't have too many pins and we don't know what
> you want to do but you may want/need to use the pin for something else.
>
> Jim
>
> ----- Original Message ----- 
> From: Alexandre Guimaraes
> To: AVR-Chat@yahoogroups.com
> Sent: Monday, July 04, 2005 5:21 PM
> Subject: [AVR-Chat] External oscillator for the Tiny13.
>
>
> Hi,
>
>    All this talk about crystals got me thinking about a cheap way to make 
> a
> external oscillator for the Tiny13.... The only thing bad about this part 
> is
> that it can not drive a crystal to make serial comms possible :-( Nothing
> can be perfect....
>
>    Does anyone have a handy, small and cheap crystal oscillator circuit
> that is reliable and uses low power ??? If it could use a resonator even
> better.... It gets cheaper and is good enough for serial communications...
>
> Best regards,
> Alexandre Guimaraes
>
>
>
>
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