Have not use my A-Star 328PB for while - and now getting this complaint from the Arduino IDE:
avrdude: warning at C:\Users\AVR\AppData\Local\Arduino15\packages\pololu-a-star\hardware\avr\4.0.2/extra_avrdude.conf:1: part m328pb overwrites previous definition C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf:8802.
Have I walked on something? 
=Alan R.
Have been digging into this - may be the presence of a (AFAIK) an obsolete folder “Arduino15” in Appdata/local & roaming. This has been causing me much confusion, and I’ve read it should just be deleted with new installations of Arduino IDE 1.8.x
Will confirm findings
Hello.
The warning you are getting from AVRDUDE is expected. Our configuration files for the A-Star 328PB provide a file called extra_avrdude.conf which tells AVRDUDE how to program an ATmega328PB. This was needed for older versions of the Arduino IDE that did not provide a definition of the ATmega328PB in avrdude.conf. The Arduino15 folder is also normal, even with new installations of the Arduino IDE 1.8.x.
-Patrick
Ok - I was thinking maybe the 328PB was now in the IDE.
But with the current settings the upload ALWAYS fails. I’ve spent about 6 hrs trying various combinations of folders, reinstalling IDE, and finally followed your instructions far a manual install of the 328PB libraries in a “hardware” folder in my “sketches” folder. I’ve tried removing the extra config file, but that fails too.
Still - EVERY TIME I try an upload it fails with that message. How must I configure the system? My project is dead in the water till I can get the 328pb running. This was working till I installed IDE 1.8.9
Any advice greatly appreciated, 
Can anything be done to remove this warning? It has thrown me off and if not needed anymore SHOULD be not seen.
Is there a new Pololu software to use with the 328PB?
BTW - the upload failure was caused by (I think) and outdated FTDI board.
Now using a new CP2104 board as an FTDI interface. Using IDE 1.8.9, Still getting distracting warning msg - but now hangs on upload. The programmer is set to "STK500 for Pololou A-Star 328PB.
If anybody has any ideas - would be great to hear something. TIA!!
If you want to remove the warning, you can edit the extra_avrdude.conf file we provide with a text editor: delete all the lines in the file so it is an empty file. However, this will not fix whatever problem is preventing you from uploading to the board.
Could you please enable verbose upload output in the Arduino IDE so we can see more details about what is going wrong? To do this, open the “File” menu, select “Preferences…”, and check the “upload” checkbox to the right of “Show verbose output during:”. After doing this, please try uploading again and post the entire output shown by the Arduino IDE so we can see what is happening.
I’d like to know more about your setup. Can you post a screenshot of your Device Manager with the “Ports (COM &LPT)” category expanded? Which type of A-Star 328PB do you have? Could you post some pictures of your setup so we can see how everything is connected? What do the LEDs on your A-Star do when you attempt to upload to it?
-Patrick
Patrick - thanks for the editing tip. I think the upload issues come from my 328PB not liking the FTDI/USB hookup I’m using. Created a new FTDI from a CP2104 and it still can’t find the board. I think had these issues last year when I started with the 328pB board.
Have abandoned the 328PB and now using the 32U4 boards - much nicer to work with (despite the strange pin-offsets!)
Case closed! 
=A.
