I have 2 STM32F4 on a board. Chip 1 will debug OK with the ULINK2 set to SW. When I set the ULINK2 to JTAG a failure is reported. PCB trace lengths are 21mm to 37mm. Chip 2 will not debug. It reports at 0xFF at address 0x08000000 (i.e. un-programmed at first program address). With the ULINK2 set to JTAG, I do not get the JTAG failure report. PCB trace lengths are 35mm to 51mm. The same occurs when I use a ULINK PRO.
Has anyone any suggestions?