NXP Semiconductors PXN2020 - 36.4 Memory Map and Registers

Nexus Development Interface (NDI)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 36-7
Refer to Chapter 3, Signal Description, and Table 3-1 for detailed signal descriptions.
36.4 Memory Map and Registers
The NDI block contains no memory mapped registers. Nexus registers are accessed by the development
tool via the JTAG port using a client select and a register index. The client select is controlled by loading
the correct access instruction into the JTAG controller, as described in Section 35.4.4, JTAGC Instructions.
After the desired client TAP is selected, OnCE registers for that client are accessible by loading the
appropriate value in the RS[0:6] field of the OnCE command register (OCMD), as described in
Section 35.5.3.1, OnCE Command Register (OCMD). Nexus is enabled, and the associated Nexus
registers become accessible, by loading the NEXUS_ENABLE instruction into the RS[0:6] field of the
OCMD. When Nexus register access is enabled, the desired Nexus register is accessible using the index
shown in Table 36-3.
Detailed sequences for Nexus3+ register access are described in Section 36.6.10.8, IEEE 1149.1 (JTAG)
RD/WR Sequences. Detailed sequences for Nexus2+ register access are described in Section 36.7.9.7,
IEEE 1149.1 (JTAG) RD/WR Sequences.
JCOMP JTAG JTAG Compliancy and TAP Sharing Control
TCK JTAG Test Clock Input
TDI JTAG Test Data Input
TDO JTAG Test Data Output
TMS JTAG Test Mode Select Input
Table 36-2. 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
e200z6 OnCE JTAG Instruction Opcodes
1
1
Refer to the e200z6 Reference Manual for a complete list of available OnCE instructions.
NEXUS3_ACCESS Opcode for e200z6 OnCE Nexus Enable instruction (10-bits) 0x7C
BYPASS Opcode for the e200z6 OnCE BYPASS instruction (10-bits) 0x7F
e200z0 OnCE JTAG Instruction Opcodes
2
2
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
Table 36-1. Signal Properties (continued)
Name Port Function