A-Star 32U4 Mini as ISP programmer

I am trying to use A-Star 32U4 Mini ULV as ISP programmer to upload a bootloader to my custom atmega32u4 board.
I connected the 6 ISP pins to the corresponding atmega32u4 ISP pins but am not able to upload.

Here is the output from just trying to query the custom board:

# avrdude -c avrisp -P /dev/cuaU0 -p atmega32u4
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x3f
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x3f
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x3f

avrdude done.  Thank you.

What am I missing and how can I solve this?
Thanks in advance.

P.S. - the output is from BSD system, but same output happens on Linux as well.

Perhaps your connections and/or programming code are incorrect, but you forgot to post any details.

In any case, the Pololu AVR Programmer v1.2 is so cheap and works so well, that you are just wasting your time.


The A-Star 32U4 Mini is not designed to be an ISP programmer, and it does not use ISP during normal operation if you are programming it via USB. You could turn an A-Star into an ISP programmer if you find some third-party ISP programmer code and load it onto the A-Star. If that is what you are trying to do, then you should refer to the documentation of that code for how to connect your target and how to troubleshoot any issues.

However, it is probably easier to just buy our Pololu USB AVR Programmer v2.1 and follow the instructions in its user’s guide.