AVR128DB48 OPAMP Voltage follower example does not work on DxCore 1.6.x

[agysft]

I tested the OPAMP Voltage_follower example on AVR128DB48.
https://github.com/SpenceKonde/DxCore/tree/master/megaavr/libraries/Opamp/examples/Voltage_follower

Environment

• MCU: AVR128DB48
• DxCore: 1.5.11 → works
• DxCore: 1.6.0 / 1.6.1 → does not work
• Bootloader was written when using DxCore 1.5.1

Problem

The OPAMP output pin (PD2) is not driven in DxCore 1.6.x.

Register check:
OPAMP.OP0CTRLA
1.5.11 → 0x07
1.6.1 → 0x06 (ENABLE bit not set)

Adding the following line fixes the problem:

OPAMP.OP0CTRLA |= OPAMP_ENABLE_bm;

---

ADC issue

Additionally, ADC seems incorrect in 1.6.x.

analogReference(VDD);
analogReadResolution(12);

The ADC result saturates near full scale.

Register check:
VREF.ADC0REF

1.5.11 → 5
1.6.1 → 0

Question

Is this a bug in DxCore 1.6.x, or has the usage changed?

[SpenceKonde]

There should be no change in behavior there these are severe and critical bugs.