Re: [avrdude-dev] ATtiny2313 and pony-stk200 problems?

[Galen Seitz]

Bob Paddock <address@hidden> wrote:

> 
> 
> >> mega48.  I ended up patching avrdude to allow the stk500 spi clock to be
> >> set to a lower speed.
> >
> > And that patch is still in the patch manager here:
> > <http://savannah.nongnu.org/patch/?func=detailitem&item_id=3136>
> 
> par.c
> /*
>   * transmit and receive a byte of data to/from the AVR device
>   */
> ... /*
>       * Due to the delay introduced by "IN" and "OUT"-commands,
>       * T is greater than 1us (more like 2us) on x86-architectures.
>       * So programming works safely down to 1MHz target clock.
>      */
> 
> That 1 MHz is probably the problem.  So I need to move the Galen's
> stk500 patch into par.c to get it down to 250 kHz as well, it would
> seem?  The patch indicates it is "STK500 only", so it needs updated to
> not be STK500 specific also.
> 

I looked at the datasheet for the tiny2313.  The default clock is the
calibrated 4 MHz osc with the CKDIV8 active, giving a frequency of
500 kHz.  The maximum SPI clock is CLK/4, so the programmer SPI clock
needs to be <= 125 kHz.

The stk500 has a command to control the SPI clock frequency, that's
why my patch is stk500 specific.  Assuming the pony is bit-banged,
my patch won't be useful to you.  A call to usleep() is what I would
use under Linux, but I don't know if this is available across all
the platforms that avrdude supports.

galen