Older LPC2xxx devices had some conditional jtag disable security functionality in bootrom.
Yes, but is this case that will permanently disable all JTAG functionality. Plesae read my anwser to Alfbaz below
the weird thing is that according to UM10503 this bits should be 0 after reset or power on but bit 10 is always set to 1.
Are there any config bits (or "fuses") that may affect the this behaviour?
The only thing I found so far is a fuse called JTAG_DISABLE (OTP memory bank 3, word 0, bit 31) on page 38 of UM10503.
Now, on table 15 (page 41) we can read the description for that fuse: "If this bit set, JTAG cannot be enabled by software and remains disabled." according to this description I think its safe to assume that this is a general way to disable all JTAG funtionality, so no way to selectively prevent a tap from being enabled by default. Also I can imply that there's a way to enable JTAG "in software"... but so far I've been unable to find it.
I haven't tried to read the OTP memory but my guess is that fuse is not set since JTAG is enabled by default on the M4 and M0APP...
Still no clue why this is happening
and no comment on the LPCWare forum so far (even for the guy that posted this issue before me on Jan)
Regards