PXR40RM Datasheet, PDF (1340/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Nexus Development Interface (NDI)
31.7.2.3.2 Retrieving Device IDCODE
The Nexus TAP controller does not implement the IDCODE instruction. However, the device
identification message can be output by the NPC through the auxiliary output port or shifted out serially
by accessing the NPC device ID register through the TAP. If the NPC is enabled, transmission of the device
identification message on the auxiliary output port MDO pins occurs immediately after a write to the PCR.
Transmission of the device identification message serially through TDO is achieved by performing a read
of the register contents as described in Section 31.7.2.3.4, Selecting a Nexus Client Register.
31.7.2.3.3 Loading NEXUS-ENABLE Instruction
Access to the NPC registers is enabled by loading the NPC NEXUS-ENABLE instruction when NPC has
ownership of the TAP. This instruction is shifted in via the SELECT-IR-SCAN path and loaded in the
UPDATE-IR state. At this point, the Nexus controller state machine, shown in Figure 31-10, transitions to
the REG_SELECT state. The Nexus controller has three states: idle, register select, and data access.
Table 31-14 illustrates the IEEE 1149.1 sequence to load the NEXUS-ENABLE instruction.
TEST-LOGIC-RESET=1
NEXUS-ENABLE=0
IDLE
NEXUS-ENABLE=1
REG_SELECT
NEXUS-ENABLE=1 && UPDATE-DR=1
UPDATE-IR=1
UPDATE-DR=1
DATA_ACCESS
Figure 31-10. NEXUS Controller State Machine
Table 31-14. Loading NEXUS-ENABLE Instruction
Clock TDI
0
—
1
—
2
—
3
—
4
—
5–7
0
8
0
9
—
10
—
TMS IEEE 1149.1 State
0 RUN-TEST/IDLE
1 SELECT-DR-SCAN
1 SELECT-IR-SCAN
0 CAPTURE-IR
0 SHIFT-IR
0 3 TCKS in SHIFT-IR
1 EXIT1-IR
1 UPDATE-IR
0 RUN-TEST/IDLE
Nexus State
Description
IDLE
IEEE 1149.1-2001 TAP controller in idle state
IDLE
Transitional state
IDLE
Transitional state
IDLE
Internal shifter loaded with current instruction
IDLE
IDLE
TDO becomes active, and the IEEE 1149.1-2001 shifter
is ready. Shift in all but the last bit of the
NEXUS_ENABLE instruction.
IDLE
Last bit of instruction shifted in
IDLE
NEXUS-ENABLE loaded into instruction register
REG_SELECT Ready to be read/write Nexus registers
31-24
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor