IEEE 1149.1 Test Access Port (JTAG)
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
29-2 Freescale Semiconductor

29.1.2 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

29.1.3 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 Section 28.5, “Background
Debug Mode (BDM)”; (JTAG_EN = 0).

29.2 External Signal Description

The JTAG module has five input and one output external signals, as described in Table 29-1.

29.2.1 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. Table 29-2 summarizes the pin function selected depending on
JTAG_EN logic state.
Table 29-1. 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