bootload 328P-AU confusion

For a start I have searched on this subject the whole morning and got nowhere before posting.

I am getting more and more confused, so if someone can just point me in the right direction please...

For several years now, I have been using stand alone 328P-PU dip chips in my projects, and have loaded the bootloader using arduino ISP with no problems. ( both v22 and 1.5 )

I have now made 3 panels with the smd chip Atmega328P-AU, but I cannot seem to burn the bootloader in the same way.

I have the reset and ISP pins connected to pins 10, 11, 12, 13 of the Arduino board ( I have tried with a Deumellinova and a Uno setting )

I have checked pin to pin continuity to the pins of the smd chip from the arduino.

When I try to burn bootloader using arduino I get :-

\ELECTRONICS\arduino1-5\arduino-1.5/hardware/tools/avr/etc/avrdude.conf -q -q -patmega328p -cstk500v1 -PCOM4 -b9600 -e -Ulock:w:0x3F:m -Uefuse:w:0x05:m -Uhfuse:w:0xDE:m -Ulfuse:w:0xFF:m

avrdude: stk500_getsync(): not in sync: resp=0xf0


What kind of 328P-AU are You using? Factory new?
At least Factory new 328P-AU Chips dont need Crystal for writing bootloader.

If You know which kind of chip are You using try the tools from Nick Gammon.

You can post shematics and/or image of the PCB of Your project.


Yes they are factory new ( from the official Atmega agent ) Atmega328P-AU chips, assembled on a pcb with 16Mhz xtal and caps, exactly the same as I have used on hundreds of other embeded 328s, except these have different pin numbers.
I have the normal 10 k from reset to Vcc, and plenty of decoupling.

What I cant understand is that people have posted that this is exactly the same internal chip as the 328P-UP but with a different package and pin numbers

John, it is the same 328P die in a different physical package. Are you wired up like a Promini, or something else?

Thanks Bob, yes as far as I know the chips are connected the same as always, ( with the different pin numbers ) perhaps I will unsolder the chip on one of them and refit it ( I farmed out the assembly )

The Atmega328P-AU is working in my setup.

Every time I have problems with loading the bootloader it turns out to be a cable connection problem. I then have to do a little ritual with the DMM to appease the ISP gods, and they scare Murphy away for a day or two.

I guess there is also a chance your assembly farm used chips they had left over from another job. Perhaps they order the things programmed for one job and put the leftover back into their stock without erasing them (is that too many details).


I believe the correct baud rate is 19200.

" I believe the correct baud rate is 19200. " thanks , how does this fit in ? ( part of my confusion with ISP )

Is this not only for serial to Rx and Tx ?

I have been trying v23 and v1.5, what should I use for the bootloader if I dont use ArduinoISP that comes with the IDE ?

I am using ribbon cable for the ISP adaptor / serial adaptor, and these old eyes missed a wire whisker shorting out 2 pins when the pcb was turned display side up.

It was fine while measuring the other way up :frowning:

So I had a short between MISO and MOSI a sort of MOSIMISO which obviously wouldn't let it communicate.

Thanks for the comments

Now for the sketch !

using arduino ISP with no problems. ( both v22 and 1.5 )

Just in case I have the wrong end of the stick... By "arduino ISP" do you mean this...

...or an Arduino-compatible board running the ArduinoISP.ino sketch with auto-reset disabled?