LM3S5C36 Datasheet, PDF (176/1068 Pages) Texas Instruments – Stellaris® LM3S5C36 Microcontroller

JTAG Interface
4.5.1.4
4.5.1.5
4.5.1.6
4.5.1.7
4.5.1.8
4.5.2
While these samples of the inputs, outputs, and output enables are being shifted out of the Boundary
Scan Data Register, new data is being shifted into the Boundary Scan Data Register from TDI.
Once the new data has been shifted into the Boundary Scan Data Register, the data is saved in the
parallel load registers when the TAP controller enters the Update DR state. This update of the
parallel load register preloads data into the Boundary Scan Data Register that is associated with
each input, output, and output enable. This preloaded data can be used with the EXTEST and
INTEST instructions to drive data into or out of the controller. See “Boundary Scan Data
Register” on page 177 for more information.
ABORT Instruction
The ABORT instruction connects the associated ABORT Data Register chain between TDI and
TDO. This instruction provides read and write access to the ABORT Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this Data Register clears various error bits or initiates
a DAP abort of a previous request. See the “ABORT Data Register” on page 178 for more information.
DPACC Instruction
The DPACC instruction connects the associated DPACC Data Register chain between TDI and
TDO. This instruction provides read and write access to the DPACC Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this register and reading the data output from this
register allows read and write access to the ARM debug and status registers. See “DPACC Data
Register” on page 178 for more information.
APACC Instruction
The APACC instruction connects the associated APACC Data Register chain between TDI and
TDO. This instruction provides read and write access to the APACC Register of the ARM Debug
Access Port (DAP). Shifting the proper data into this register and reading the data output from this
register allows read and write access to internal components and buses through the Debug Port.
See “APACC Data Register” on page 178 for more information.
IDCODE Instruction
The IDCODE instruction connects the associated IDCODE Data Register chain between TDI and
TDO. This instruction provides information on the manufacturer, part number, and version of the
ARM core. This information can be used by testing equipment and debuggers to automatically
configure input and output data streams. IDCODE is the default instruction loaded into the JTAG
Instruction Register when a Power-On-Reset (POR) is asserted, or the Test-Logic-Reset state is
entered. See “IDCODE Data Register” on page 177 for more information.
BYPASS Instruction
The BYPASS instruction connects the associated BYPASS Data Register chain between TDI and
TDO. This instruction is used to create a minimum length serial path between the TDI and TDO ports.
The BYPASS Data Register is a single-bit shift register. This instruction improves test efficiency by
allowing components that are not needed for a specific test to be bypassed in the JTAG scan chain
by loading them with the BYPASS instruction. See “BYPASS Data Register” on page 177 for more
information.
Data Registers
The JTAG module contains six Data Registers. These serial Data Register chains include: IDCODE,
BYPASS, Boundary Scan, APACC, DPACC, and ABORT and are discussed in the following sections.
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January 23, 2012
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