AVR-Chat

Russell

I don't have a storage scope (must get one - cheap enough now) but I have 
checked mosi/miso/reset signals with my old cro and the STK500 is definitely 
trying to talk to the 168 but giving up pretty quickly. Does changing miso 
suggest that the 168 is trying to respond? Or perhaps the STK sets a pull-up 
on this line.

As per my earlier email, the STK and cable have been tested against my 
earlier M8 version of the board and work fine.

I take it from your responses that I should reasonably expect a brand new 
168 with external xtal to accept ISP programming?

Thanks,
Mark

>>>
>>>>>If the xtal in/out pins are VCC/2, then the xtal should be oscillating.
>>>>>
>>>>
>>>>I appear to have ~0.2V on both xtal pins, so not VCC/2 (5V VCC).
>>>>
>>>>Mark
>>>
>>>Then the xtal isn't the problem.
>>>
>>>Make sure none of the programming pins or the reset pin are being
>>>loaded by other components on the pcb. That includes things like
>>>capacitors connected to the reset pin.
>>>
>>
>> I had a 10k pull-up and 0.1uF cap on Reset - I didn't think the cap was 
>> big
>> enough to cause trouble but I took it out anyway. I also had 6k2 pull-ups 
>> on
>> MOSI/MISO which I've again removed. No change.
>>
>
> If there's nothing interfering with the pins, then i don't know. Maybe
> you could test if the stk500 works on a different chip.
>
> See if there's any waveforms on the reset/mosi/miso pins with a cro
> when attempting programming.
>