ST Link + CubeMX IDE won't connect to my STM32H725IGT Board

[ChrisP1000]

Hi,

I have a new design using the STM32H725IGT. The STM32H725IGT is a 176 pin QFP. The power rails have all checked out as good but I can't connect to it to program it. I have tried two ST-link V2's and two separate boards with no success. Both ST links updated their firmware successfully  and are seen by the CubeMX IDE. We are also using the Olimex adapter to enable a smaller connecter. This is the PCB layout of that:

The on-board connector is the Samtec FTSH-105-01-F-DV-007-K, so an Olimex ARM-JTAG-20-10 is used to convert the large 20-pin ST-link connector down to 10 pin. As can be seen in the above image, 

SWCLK goes to pin 138 of the STM32H725IGT
SWDIO goes to pin132 of the STM32H725IGT
On the FTSH-105-01-F-DV-007-K, pins 3 & 5 are GND, 1 is +3.3V, 2 is SWDIO, 4 is SWCLK. Pin 6 is connected as JTDO-SWO. Pins 6 and 8 are, I believe not used by the ST-link. Pin 10 connects to pin 33 of the STM32H725IGT, nRST. The nRST is labelled JnTRST for JTAG programmers, but it is actually just nRST and connects via a 0R link to nRST.

I have used this exact pin-out and connector combination previously for an STM32F7 and it worked flawlessly. The connector on board is correct orientation, since Olimex part uses keyed connectors at all points it is a little difficult to get them the wrong way round,

Using a scope during programming attempt  I can see that 3.3V is on pin 1 of connector; there is a burst of activity on both SWDIO and SWCLK; nRST toggles high to low and back to high at end. VDDA is 3.3V at the pin according to scope. VREF is 3.3V at pin MCU VDD is 3.3V at pins VCAP pins are connected together with 3 x 10nF caps. Each pin has a cap at the pin

BOOT0 is tied to GND through a resistor and has been confirmed with a scope
Power configuration is shown in the following schematic:

I am at a loss to know what else to check. Can anyone please help?

[ChrisP1000]

I should add, the firmware I am trying to install is just whatever CubeMX provides as default and it compiles with 0 errors and 0 warnings. There is no firmware on the device

[Tesla DeLorean]

Shouldn't VCAP have around 4u7 F on it? Should be able to measure about 1.25V

[AScha.3]

Hi,

so you use direct-smps :

- but i see no connection vfbsmps -> vcap ??

- whats core voltage at vcap ?

+

- you have 3v3 at vddldo - but "not used" written there; but for direct-smps-mode it should be connected to vfbsmps+vcap !

Something wrong : your connections or your info here. Adjust it.