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?
I have not daisy chained the JTAG, I have 2 separate JTAG connectors. I also have a separate FPGA JTAG, again separate. I am not brave enough to daisy chain them all.
On two previous boards I have connected JTAG, (TMS,TCK,TDI,TDO), a hardware reset pin and TRST connected to PB4 (TRST pin for STM32F4). I read in the Kiel ULINK manuals that the TRST pin is not required, so I have not connected it this time, and used the pin for something else. I have connected the trace pins CLK, D0,D1,D2,D3. In the ULINKs, nTRST is multiplexed with TRACE_D1 according to the Keil manual. I am using both a ULINK2 as well as the ULINK PRO, and ULINK2 does not have any trace facility, and only 10 connections I assume this has no bearing on my problem.
regards Konrad