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MC68360 USER’S MANUAL
SECTION 8
SCAN CHAIN TEST ACCESS PORT
The QUICC provides a dedicated user-accessible test access port (TAP) that is JTAG com-
patible.
The QUICC TAP contains one additional signal not available with the MC68340 TAP—the
test reset (TRST) signal. This signal provides an asynchronous reset to the TAP.
The TAP consists of five dedicated signal pins, a 16-state TAP controller, and two test data
registers. A boundary scan register links all device signal pins into a single shift register. The
test logic, implemented utilizing static logic design, is independent of the device system log-
ic. The QUICC implementation provides the capability to:
1. Perform boundary scan operations to test circuit-board electrical continuity.
2. Bypass the QUICC for a given circuit-board test by effectively reducing the boundary
scan register to a single cell.
3. Sample the QUICC system pins during operation and transparently shift out the result
in the boundary scan register.
4. Disable the output drive to pins during circuit-board testing.
NOTE
Certain precautions must be observed to ensure that the IEEE
1149.-like test logic does not interfere with nontest operation.
See 8.6 Non-Scan Chain Operation for details.
In addition to the scan-test logic, the QUICC contains a signal that can be used to three-state
all QUICC output signals. This signal, called three-state (TRIS), is sampled during system
reset when the QUICC is not in slave mode.
8.1 OVERVIEW
An overview of the QUICC scan chain implementation is shown in Figure 8-1. The QUICC
implementation includes a TAP controller, a 3-bit instruction register, and two test registers
(a 1-bit bypass register and a 196-bit boundary scan register). This implementation includes
a dedicated TAP consisting of the following signals:
TCK—a test clock input to synchronize the test logic.
TMS—a test mode select input (with an internal pullup resistor) that is sampled on the
rising edge of TCK to sequence the TAP controller’s state machine.
TDI—a test data input (with an internal pullup resistor) that is sampled on the rising
edge of TCK.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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