I'm having an issue with the JTAG port of MPC5748G (Calypso), BGA 256 package.
When there is an application in the flash, everything works fine. When the flash is empty,
the JTAG ID can be read correctly, and access can be granted to the Z4A Nexus port.
It is also possible to reclaim the TAP access from Nexus through "Pause-DR".
But when the Nexus is active, nothing is working. The chip returns zeros only on TDI for
all commands, OSR cannot be read either.
Any help would be welcome, how to activate OnCE/Nexus when there is no active boot
block in the device.