This is a new A-Star 328PB, so no debugWIRE fuse should ever have been set. I am using Atmel Studio 7, with the Programmer connected via the 6-pin ISP connector cable. I aded the STK500 as a target, and went to Device Programming. Select the STK500, select the ATmega328PB, ISP Interface, then Apply. I can read the target voltage (4.1V), but when I go to read the Device Signature I get an error message that I “Failed to Enter Programming Mode”. Is there a chance the A-Star came with the debugWIRE fuse set?
No; the debugWIRE fuse should not be set.
I suspect the issue is probably due to the A-Star 328PB’s VCC line being outside the Pololu USB AVR Programmer v2.1’s acceptable range. You can see the VCC 3.3 V and 5 V minimum and maximum settings in the Pololu USB AVR Programmer v2 Configuration Utility. You might consider powering your A-Star 328PB a different way, or changing the programmer’s settings so that it does not consider 4.1 V to be an error. Please let me know if you have any additional questions.
By the way, in case you do not already know, you can use the Pololu USB AVR Programmer v2.1 supply power to the A-Star 328PB (which is useful for powering low-current systems from USB). You can find more details on the AVR programmer’s power settings under the “Power settings and status” in the Pololu USB AVR Programmer v2 User’s Guide.