What Is The Trick To Burning Bootloaders In New Chips?

I've designed a number of boards using, mostly, AVR 328Ps. All of them have worked flawlessly, except.... I've never been able to burn bootloaders into them using a USBTinyISP. I have been able to use the same USBTinyISP to burn bootloaders in several Nanos and ProMinis, though I have also had ProMinis and Nanos that would not allow me to change the bootloaders.

What is the trick to making this work? I have a 6-pin connector, wired up exactly as it is on the Nano. I have nothing unusual connected to the 328P that should interfere. The RST pin has a resistor and cap, exactly as on the Nano. Yet, it does not work. I MUST be missing something...

Regards,
Ray L.

Well, I'm an idiot! You should never check your own work.... I had a bonehead wiring error. Works fine now.

Regards,
Ray L.

Sh*t happens.

RayLivingston:
I had a bonehead wiring error.

To be fair, that's pretty much the only explanation for the symptoms you reported :slight_smile: It is incredibly easy to get the connections wrong when you are manually connecting up each pin instead of plugging into an ISP connector.