Cortex M0 SWD programming issue.

[avc4eva]

Hi all,

To keep this short and sweet:

I am programming an Cortex M0 nrf51822 MCU and has been going great on another of my projects, this project (in schematic) is causing trouble programing over swd.

Currently to program i am using a Keil Ulink PRO with a tc2032 tag connect to the board, i used to use the VCC from the u link/tc2032 for programing but omitted this as I can power the device by usb or LiPo while programing, however this seems to be causing issue.

If i use my previous board which allows to power via the ulink  the board is recognized in keil, however if i remove the power and simply power by the usb or LiPo i get nothing.

Any ideas?

The schematic is attached.

EDIT: The TC2032 VCC was connected before to +3v3 and thus directly to the chip and not through LDO.

[avc4eva]

Solved:

Was due to the ulink not sharing common ground with board, now fixed!