NXP Semiconductors MWCT101 S Series, Reference Manual

Page: 1738 / 1761

51.5.4.3 SAMPLE instruction
The SAMPLE instruction obtains a sample of the system data and control signals present
at the MCU input pins, and just before the boundary scan register cells at the output pins.
This sampling occurs on the rising edge of TCK in the Capture-DR state when the
SAMPLE instruction is active. The sampled data is viewed by shifting it through the
boundary scan register to the TDO output during the Shift-DR state. There is no defined
action in the Update-DR state. Both the data capture and the shift operation are
transparent to system operation.
51.5.4.4 EXTEST external test instruction
EXTEST selects the boundary scan register as the shift path between TDI and TDO. It
allows testing of off-chip circuitry and board-level interconnections by driving preloaded
data contained in the boundary scan register onto the system output pins. Typically, the
preloaded data is loaded into the boundary scan register using the SAMPLE/PRELOAD
instruction before the selection of EXTEST. EXTEST asserts the internal system reset for
the MCU to force a predictable internal state when performing external boundary scan
operations.
51.5.4.5 ENABLE_SOC_DATA1 instruction
The ENABLE_SOC_DATA1 instruction captures SoC data and selects the SOC_DATA
register for connection as the shift path between TDI and TDO.
51.5.4.6 HIGHZ instruction
HIGHZ selects the bypass register as the shift path between TDI and TDO. When
HIGHZ is active all output drivers are placed in an inactive drive state (for example, high
impedance). HIGHZ also asserts the internal system reset for the MCU to force a
predictable internal state.
51.5.4.7 CLAMP instruction
CLAMP allows the state of signals driven from MCU pins to be determined from the
boundary scan register when the bypass register is selected as the serial path between TDI
and TDO. CLAMP enhances test efficiency by reducing the overall shift path to a single
Functional description
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
1738 NXP Semiconductors