Programming custom board STM32G0B1RET

[micropap]

Hi,

I'm trying to program one custom board with STM32G0B1RET using original STLINK V3 and STLINK V2 without succes.

My schematic is very simple as you can see on the image:

And the response all time is: Not STM32 target found.. if I use SWD port. 

If I use JTAG the response is:  ST-LINK error (DEV_UNKNOWN_MCU_TARGET)

I've revised all the connections, voltages (both on the board and STLINK-V2), capacitors, lowered freq.,etc without success.

Also I've tried with Hot plug, Hardware Reset, Power down, Under reset, etc. 

The log is like this:

22:03:41 : ST-LINK SN : 0672FF485570854967095517
22:03:41 : ST-LINK FW : V2J46M32
22:03:41 : Board : NUCLEO-G0B1RE
22:03:41 : Voltage : 0.02V
22:03:41 : Error: Unable to get core ID
22:03:41 : Error: ST-LINK error (DEV_UNKNOWN_MCU_TARGET)

What can be the problem?

I've 25 years designing electronics and is not my first board with STM32 devices (the previous one works perfectly) but I've finish all my arsenal of knowledge!

Thanks.

[Pavel A.]

22:03:41 : Voltage : 0.02V
22:03:41 : Error: Unable to get core ID

Target voltage 0.02V? Not good.

>25 years designing electronics and is not my first board with STM32 devices

How the STM32 can know this? It's a small dumb chip, it just wants its power.

[micropap]

Thanks to respond Pavel A.

Because of this I said: "I've revised all the voltages..." I've ensured that in the STLINK the voltage is 3.29V (a little bit less than in the regulator because on the STLINK they allocate a serial diode as protection. I've measured the voltage using the GND pins on the STLINK not from my board.GND.

If I'm right if I connect the Nucleo dev board the voltage it shows the same value, but connects.

Only if I connect using JTGA option, the programmer shows the right voltage that in fact is present.

Regards.