Microcontroller User's Manual

31-2 MCF5282 User’s Manual MOTOROLA

Features

Figure 31-1. JTAG Block Diagram

31.1 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 shift out the result

• Selects between JTAG TAP controller and Background Debug Module (BDM)

using a dedicated JTAG_EN pin

4-BIT TAP INSTRUCTION REGISTER

1-BIT BYPASS REGISTER

148-BIT BOUNDARY SCAN REGISTER

32-BIT IDCODE REGISTER

TRST/DSCLK

TCLK

TMS/BKPT

031

0147

TAP CONTROLLER

TDI/DSI

TDO/DSO

JTAG Module

to Debug Module

7-BIT JTAG_CFM_CLKDIV REGISTER

3-BIT TEST_CTRL REGISTER

4-BIT TAP INSTRUCTION DECODER

Disable DSCLK

Force BKPT = 1

DSI = 0

JTAG_EN

DSO

DSI

BKPT

DSCLK