LM3S5G31 Datasheet, PDF (181/1223 Pages) Texas Instruments – Stellaris LM3S5G31 Microcontroller

Stellaris^® LM3S5G31 Microcontroller
4.5.1.2
4.5.1.3
4.5.1.4
4.5.1.5
4.5.1.6
INTEST Instruction
The INTEST instruction is not associated with its own Data Register chain. Instead, the INTEST
instruction uses the data that has been preloaded into the Boundary Scan Data Register using the
SAMPLE/PRELOAD instruction. When the INTEST instruction is present in the Instruction Register,
the preloaded data in the Boundary Scan Data Register associated with the inputs are used to drive
the signals going into the core rather than the signals coming from the GPIO pads. With tests that
drive known values into the controller, this instruction can be used for testing. It is important to note
that although the RST input pin is on the Boundary Scan Data Register chain, it is only observable.
While the INTEST instruction is present in the Instruction Register, the Boundary Scan Data Register
can be accessed to sample and shift out the current data and load new data into the Boundary Scan
Data Register.
SAMPLE/PRELOAD Instruction
The SAMPLE/PRELOAD instruction connects the Boundary Scan Data Register chain between
TDI and TDO. This instruction samples the current state of the pad pins for observation and preloads
new test data. Each GPIO pad has an associated input, output, and output enable signal. When the
TAP controller enters the Capture DR state during this instruction, the input, output, and output-enable
signals to each of the GPIO pads are captured. These samples are serially shifted out on TDO while
the TAP controller is in the Shift DR state and can be used for observation or comparison in various
tests.
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 183 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 183 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 183 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 183 for more information.
July 03, 2014
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