Chapter 35 IEEE 1149.1 Test Access Port Controller (JTAGC)
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
857
35.5.2.1
Bypass mode
When no test operation is required, the BYPASS instruction can be loaded to place the JTAGC into bypass
mode. While in bypass mode, the single-bit bypass shift register provides a minimum-length serial path to
shift data between TDI and TDO.
35.5.2.2
TAP sharing mode
There are four selectable auxiliary TAP controllers that share the TAP with the JTAGC. Selectable TAP
controllers include the Nexus port controller (NPC), e200 OnCE, and eDMA Nexus. The instructions
required to grant ownership of the TAP to the auxiliary TAP controllers are ACCESS_AUX_TAP_ONCE
and ACCESS_AUX_TAP_NPC. Instruction opcodes for each instruction are shown in
When the access instruction for an auxiliary TAP is loaded, control of the JTAG pins is transferred to the
selected TAP controller. Any data input via TDI and TMS is passed to the selected TAP controller, and any
TDO output from the selected TAP controller is sent back to the JTAGC to be output on the pins. The
JTAGC regains control of the JTAG port during the UPDATE-DR state if the PAUSE-DR state was
entered. Auxiliary TAP controllers are held in RUN-TEST/IDLE while they are inactive.
For more information on the TAP controllers refer to
Chapter 36, “Nexus Development Interface (NDI).
35.6
External signal description
The JTAGC consists of four signals that connect to off-chip development tools and allow access to test
support functions. The JTAGC signals are outlined in
.
35.7
Memory map and registers description
This section provides a detailed description of the JTAGC registers accessible through the TAP interface,
including data registers and the instruction register. Individual bit-level descriptions and reset states of
each register are included. These registers are not memory-mapped and can only be accessed through the
TAP.
Table 35-1. JTAG signal properties
1
1
Test clock frequency must always be less than one fourth of system clock frequency.
Name
I/O
Function
Reset state
Pull
2
2
The pull is not implemented in this module. Pullup/down devices are implemented in the pads.
TCK
I
Test clock
—
Down
TDI
I
Test data in
—
Up
TDO
O
Test data out
High Z
3
3
TDO output buffer enable is negated when JTAGC is not in the Shift-IR or Shift-DR states. A weak
pulldown can be implemented on TDO.
Down
TMS
I
Test mode select
—
Up