Freescale Semiconductor MPC5604B - Enabling Nexus Clients for TAP Access

MPC5604B/C Microcontroller Reference Manual, Rev. 8
816 Freescale Semiconductor
On HALT or STOP mode exit, the MC_ME asserts the lp_mode_exit_req input after ensuring that the
regulator and memories are in normal mode and before the processor exits its halted or stopped state. The
mode transition will then not proceed until the lp_mode_exit_ack output has been asserted. The MC_RGM
asserts the exit_from_standby input when executing a reset sequence due to a STANDBY exit. The reset
sequence will then not complete until the lp_mode_exit_ack output has been asserted.
The notification to the debugger of a low-power mode exit consists of driving the TDO pad to `0'. The
debugger acknowledges that the transition from a low-power mode can continue by setting the low-power
mode sync bit in the port control register (written by debugger), which results in the assertion of the
lp_sync_out input.
NOTE
The debugger clock multiplexer may not guarantee glitch free switching.
Therefore, TCK should be disabled from when the debugger clears the sync
bit in ENTRY_CLR until the debugger senses the falling edge of TDO in
TDO_SET.
33.7.2 Enabling Nexus Clients for TAP Access
After the conditions have been met to bring the NDI out of the reset state, the loading of a specific
instruction in the JTAG controller (JTAGC) block is required to grant the NDI ownership of the TAP. Each
Nexus client has its own JTAGC instruction opcode for ownership of the TAP, granting that client the
means to read/write its registers. The JTAGC instruction opcode for each Nexus client is shown in
Table 33-11. After the JTAGC opcode for a client has been loaded, the client is enabled by loading its
NEXUS-ENABLE instruction. The NEXUS-ENABLE instruction opcode for each Nexus client is listed
in Table 33-12. Opcodes for all other instructions supported by Nexus clients can be found in the relevant
sections of this chapter.
Table 33-11. JTAGC Instruction Opcodes to Enable Nexus Clients
JTAGC Instruction Opcode Description
ACCESS_AUX_TAP_NPC 10000 Enables access to the NPC TAP controller
ACCESS_AUX_TAP_ONCE 10001 Enables access to the e200z0 TAP controller
Table 33-12. Nexus Client JTAG Instructions
Instruction Description Opcode
NPC JTAG Instruction Opcodes
NEXUS_ENABLE Opcode for NPC Nexus ENABLE instruction (4-bits) 0x0
BYPASS Opcode for the NPC BYPASS instruction (4-bits) 0xF
e200z0 OnCE JTAG Instruction Opcodes
1
1
Refer to the e200z0 reference manual for a complete list of available OnCE instructions.
NEXUS2_ACCESS Opcode for e200z0 OnCE Nexus ENABLE instruction (10-bits) 0x7C
BYPASS Opcode for the e200z0 OnCE BYPASS instruction (10-bits) 0x7F