Boundary Scan Register - Freescale Semiconductor MPC850 User Manual

TEST LOGIC
RESET
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RUN—TEST/IDLE
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45.3 Boundary Scan Register

The MPC850 scan chain consists of a 397-bit boundary scan register that contains bits for
all signals, with the exception of the XTAL, EXTAL, and XFC pins, which are analog
signals. An IEEE-1149.1 compliant boundary scan register has been included on the
MPC850. This 397-bit boundary scan register can be connected between TDI and TDO
when EXTEST or SAMPLE/PRELOAD instructions are selected. The boundary scan
register is used for capturing data on the input signals, forcing fixed values on the output
signals, and selecting the direction and drive characteristics (a logic value or high
impedance) of the bidirectional and three-state signals.
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SELECT—DR_SCAN
CAPTURE—DR
SHIFT—DR
EXIT1—DR
PAUSE—DR
EXIT2—DR
UPDATE—DR
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Figure 45-2. TAP Controller State Machine
Chapter 45. IEEE 1149.1 Test Access Port
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SELECT—IR_SCAN
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Boundary Scan Register
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CAPTURE—IR
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SHIFT—IR
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EXIT1—IR
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PAUSE—IR
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EXIT2—IR
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UPDATE—IR
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