I have a board with LPC5528JBD64K and for configuring it I use MCUXpresso IDE. MCU is ok (UART, ADC and other peripherals work), but I cannot flash and debug it using J-link, cuz error "Wrong DM-AP IDCODE detected" appears.
SWD clock is configured in MCUXpresso. Connection between MCU and SWD pins is ok. I tried to pull ISP entry pin to VCC and GND, nothing changes.
It is my first time with LPC, so, maybe, I forget to set some bits or anything else to turn debugging on.
About the SWD hardware design, you can refer to LPCxpresso55s28 board:
In MCUXpresso IDE, Just click "Debug" button under Quickstart Panel:
If still can't work, please take a video or take screenshot to show your steps.
You can have a look at this thread:
And about the J-link debug, recommend you also ask help on Segger support, they know the j-link deep.