MPC555 / MPC556
IEEE 1149.1-COMPLIANT INTERFACE (JTAG)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
22-1
SECTION 22
IEEE 1149.1-COMPLIANT INTERFACE (JTAG)
The MPC555 / MPC556 includes dedicated user-accessible test logic that is fully com-
patible with the
IEEE 1149.1-1990 Standard Test Access Port and Boundary Scan Ar-
chitecture
. Problems associated with testing high-density circuit boards have led to
development of this standard under the sponsorship of the Test Technology Commit-
tee of IEEE and the Joint Test Action Group (JTAG). The MPC555 / MPC556 supports
circuit-board test strategies based on this standard.
This section is intended to be used with the supporting IEEE 1149.1-1990 standard.
The scope of this description includes those items required by the standard to be de-
fined and, in certain cases, provides additional information specific to the implementa-
tion. For internal details and applications of the standard, refer to the IEEE 1149.1-
1990 document.
An overview of the JTAG pins on the MPC555 / MPC556 is shown in
Figure 22-1 JTAG Pins
Boundary scan cells (BSC) are placed at the digital boundary of the chip (normally the
package pins). The boundary scan cells are chained together to form a boundary scan
register (BSR). The data is serially shifted in through the serial port (TDI) and serially
shifted out through the output port (TDO).
22.1 JTAG Interface Block Diagram
A block diagram of the MPC555 / MPC556 implementation of the IEEE 1149.1-1990
test logic is shown in
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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