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Introduction
184
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
JTAG Interface
3.1
Introduction
The JTAG port is composed of four pins: TCK, TMS, TDI, and TDO. Data is transmitted serially into the
controller on TDI and out of the controller on TDO. The interpretation of this data is dependent on the
current state of the TAP controller. For detailed information on the operation of the JTAG port and test
access port (TAP) controller, see the IEEE Standard 1149.1-Test Access Port and Boundary-Scan
Architecture.
The MSP432E4 JTAG controller works with the Arm
®
JTAG controller built into the Cortex
®
-M4F core by
multiplexing the TDO outputs from both JTAG controllers. Arm JTAG instructions select the Arm TDO
output while JTAG instructions select the TDO output. The multiplexer is controlled by the JTAG controller,
which has comprehensive programming for the Arm core, MSP432E4 microcontroller, and unimplemented
JTAG instructions.
The JTAG module has the following features:
•
IEEE 1149.1-1990 compatible TAP controller
•
Four-bit Instruction Register (IR) chain for storing JTAG instructions
•
IEEE standard instructions: BYPASS, IDCODE, SAMPLE/PRELOAD, and EXTEST
•
Arm additional instructions: APACC, DPACC, and ABORT
•
Integrated Arm Serial Wire Debug (SWD)
–
Serial Wire JTAG Debug Port (SWJ-DP)
–
Flash Patch and Breakpoint (FPB) unit for implementing breakpoints
–
Data Watchpoint and Trace (DWT) unit for implementing watchpoints, trigger resources, and
system profiling
–
Instrumentation Trace Macrocell (ITM) for support of printf style debugging
–
Embedded Trace Macrocell (ETM) for instruction trace capture
–
Trace Port Interface Unit (TPIU) for bridging to a Trace Port Analyzer
See the Arm Debug Interface V5 Architecture Specification for more information on the Arm JTAG
controller.
3.2
Block Diagram
shows the block diagram of the JTAG module.
Figure 3-1. JTAG Module Block Diagram