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IEEE 1149.1 Test Access Port (JTAG)
35-2
Freescale Semiconductor
35.1.2
Features
The basic features of the JTAG module are the following:
•
Performs boundary-scan operations to test circuit board electrical continuity
•
Bypasses instruction to reduce the shift register path to a single cell
•
Sets chip output pins to safety states while executing the bypass instruction
•
Samples the system pins during operation and transparently shifts out the result
•
Selects between JTAG TAP controller and Background Debug Module (BDM) using a dedicated
JTAG_EN pin
35.1.3
Modes of Operation
The JTAG_EN pin can select between the following modes of operation:
•
JTAG mode (JTAG_EN = 1)
•
Background debug mode (BDM)—for more information, refer to
; (JTAG_EN = 0).
35.2
External Signal Description
The JTAG module has five input and one output external signals, as described in
35.2.1
JTAG Enable (JTAG_EN)
The JTAG_EN pin selects between the debug module and JTAG. If JTAG_EN is low, the debug module is
selected; if it is high, the JTAG is selected.
summarizes the pin function selected depending on
JTAG_EN logic state.
Table 35-1. Signal Properties
Name
Direction
Function
Reset State
Pull up
JTAG_EN
Input
JTAG/BDM selector input
—
—
TCLK
Input
JTAG Test clock input
—
Active
TMS/BKPT
Input
JTAG Test mode select / BDM Breakpoint
—
Active
TDI/DSI
Input
JTAG Test data input / BDM Development serial input
—
Active
TRST/DSCLK
Input
JTAG Test reset input / BDM Development serial clock
—
Active
TDO/DSO
Output
JTAG Test data output / BDM Development serial output
Hi-Z / 0
—
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...