A solar MPPT controller is applied using the stm32f030 mcu, and the charging voltage can be changed using an external interface. A phenomenon in which the charging value changes during operation occurs.

[ghan.1]

Try to connect the receiving terminal of the external interface connection terminal to GND. Will this help with program changing issues?

[LCE]

What's the controller's VSS pin connected to?

[ghan.1]

Connected to output ground.