I can't connect my Nucleo to my STM32L0 board

[MatheusMarkies]

Well, I'm new to the STM32. I'm developing vibration and temperature sensors, which used to be equipped with an atmega.
With the new demand for processing I decided to upgrade by putting an STM32L0 in place of the old controller.
The problem is that now I can't use my CUBE Programmer to connect to my board via Nucleo's STM Link.
An error message appears whenever I click Connect, and my Nucleo board flashes red.
I think I may have made a connection or PCB design error.

Information:
My system has 1 accelerometer 1 temperature sensor 1 Lora radio 1 battery sensor and a 3v3 regulator.
The clock has been set to 25KHz by means of an Oscillator Crystal.
and the BOOT0 pin is not connected to anything other than the pull-down resistor.

[Tesla DeLorean]

The error is that it can't even find the ST-LINK / NUCLEO, so perhaps a short or power issue.

I'd assume you've used the NUCLEO previously? Which model of NUCLEO?

Does it show up in Device Manager?

[MatheusMarkies]

I've used NUCLEO a few times, and it works perfectly. I made a new board soldering only the STM32 system and now my NUCLEO is showing up in the device manager and also in the Programmer.
However, I can't connect to it.

[Andrew Neil]

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@MatheusMarkies wrote:

I made a new board soldering only the STM32 system and now my NUCLEO is showing up in the device manager and also in the Programmer.
However, I can't connect to it.

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So you're using the ST-Link part of your Nucleo board to program your own custom board?

Are you sure you've set all the links correctly for that?

Does the Nucleo's ST-Link still work with the Nucleo Target?

[Tesla DeLorean · Accepted solution]

Ok, so now it sees the ST-LINK

The complaint is the target is not viable.

So power and connections become critical. Schematic looks reasonable. Check components and orientation. Common grounds. Check state/level of NRST signal

The target will need both analogue and digital supplies connected.

SWCLK, SWDIO, GND

The CM0(+) will not support PB3/SWO

Disconnect the local target on the NUCLEO-F103RB board, pair of jumpers.

[MatheusMarkies]

So... I didn't touch anything, I just plugged it back into the computer, and now it works 🤔

But as you said above, I won't have SWO support on this chip, so I'm not sure how I can debug it to see if everything is working.

[Andrew Neil]

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@MatheusMarkies wrote:

I won't have SWO support on this chip, so I'm not sure how I can debug it 

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You don't need SWO to debug - only SWCLK & SWDIO.

Use a UART TX out to give "realtime" diagnostic output ...

https://wiki.segger.com/SWO