Nucleo-H563ZI shows a constant 660mV on DAC output in idle state

nagahimanshu7 · ‎2025-09-24

Hi,

I am working on DAC on Nucleo-H563ZI board. I am using PA4 on ST Morpho header as DAC1_OUT1.

In idle state when the USER USB port is connected (irrespective of ST-LINK port connection), it shows a constant voltage of 660mV on output.

During sine generation using DAC, there is no offset of this voltage observed and the output is in range.

But if the USER USB is not connected, the output remains 0V. What could probably be causing the 660mV idle state output?

AScha.3 · ‎2025-09-24

Hi,

from circuit of Mb1404 , PA4 is connected to VBUS_SENSE .

+

So open SB56 , if you dont want to use vbus-sense or need "free" PA4.

If you feel a post has answered your question, please click "Accept as Solution".

View solution in original post

Andrew Neil · ‎2025-09-24

Have you checked the schematics?

eg, is there anything connected to that pin related to the User USB?

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

AScha.3 · ‎2025-09-24

Hi,

from circuit of Mb1404 , PA4 is connected to VBUS_SENSE .

+

So open SB56 , if you dont want to use vbus-sense or need "free" PA4.

If you feel a post has answered your question, please click "Accept as Solution".

nagahimanshu7 · ‎2025-09-24

Hi @Andrew Neil @AScha.3

Thanks for the inputs.

Andrew Neil · ‎2025-09-24

You're welcome.

Always important to check the board schematics!

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.