First of all, to any mod, if I've posted this in the wrong area of the forum, please feel free to move it!
Here's my problem: I have been programming ATTiny85s successfully for a while using a Uno as an ISP and a TinyShield AVR programmer shield, but now I'm trying to program surface mount ATTiny85s with the same program and its just not happening. I keep getting the error message:
avrdude: Yikes! Invalid device signature. Double check connections and try again, or use -F to override this check
I made my own adapter to allow the programming of the smd chips and I've double and triple checked its correct wiring and all's ok there.
The through hole chips still program ok. The only difference, apart from the chip format, is that the through hole chips are -20PU and the smd chips are -10PU. Does this mean the loading of bootloaders? I'm a bit vague about this area of knowledge I'm afraid. The through hole chips took the programming without any need, so why don't the smd chips?
I realise that the answer is probably obvious to some, but not to an old newby like me I'm afraid!!