Re: [avrdude-dev] Calibration bytes on ATmega8

[Francisco T. A. Silva]

Brian Dean wrote:
> On Tue, May 06, 2003 at 05:40:13PM -0300, Francisco T. A. Silva wrote:
>
>
> > The Atmega8 has 4 calibration bytes. The atttached patch makes it 
> > possible for avrdude to read them all.
>
>
> The data sheet speaks only of a single calibration byte.  If you can
> show where this is documented somewhere in the datasheet or perhaps in
> an errata somewhere, I have no problem adding this to the
> configuration.  However, I don't think it's wise to deviate from the
> documented data sheets too much.  For example, even if this works for
> some parts, since it's not documented in the data sheet Atmel is free
> to change the behaviour at any time, and we probably should not rely
> on it being there.
>
> -Brian

Hi Brian,

I have a pdf ATMEGA8 data sheet Rev. 2486J AVR 02/03.

In it I find:
page 220 under "Calibration Byte"

The ATmega8 stores four different calibration values for the internal RC 
Oscillator. These bytes resides in the signature row High Byte of the 
addresses 0x000, 0x0001, 0x0002, and 0x0003 for 1, 2, 4, and 8 Mhz 
respectively. During Reset, the 1 MHz value is automatically loaded into 
the OSCCAL Register. If other frequencies are used, the calibration 
value has to be loaded manually, see  Oscillator Calibration Register 
OSCCAL  on page 29 for details.

Regards,
--
Francisco

PS: the sp12 programmer suports the four calibration bytes.