AVR-Chat

Mark Nowell wrote:
> I've got two new Mega168 boards which I'm trying to program via STK500/ISP 
> but the STK500 doesn't appear to be talking to the AVR - "Entering 
> programming mode .. FAILED!" on Read Signature. This is the first time I've 
> tried to use the STK500 for ISP - used to use an Equinox serial/parallel 
> programmer but it doesn't support the 168. The new boards have minor changes 
> from a previous Mega8 design - the STK500 will talk to the Mega8, so that 
> much of it is working and suggests there's nothing fundamentally wrong with 
> the circuit.
> 
> The 168's are samples direct from local supplier and I assume should be in 
> default/unprogrammed state. Clock (external 16MHz xtal) isn't running but I 
> guess it won't until the relevant fuses are set? This is the first time I've 
> had to use a SM AVR and I can't remember if I've previously had to parallel 
> program the Mega8's before I could use ISP. Should I not expect to be able 
> to do ISP from scratch? Could it be the external xtal that's the problem?
> 
> Thanks,
> Mark 

If the xtal in/out pins are VCC/2, then the xtal should be oscillating.