AM3874 datasheet(219/361 Pages) TI

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AM3874, AM3871

www.ti.com

SPRS695C – SEPTEMBER 2011 – REVISED DECEMBER 2013

8.5

Emulation Features and Capability

8.5.1

Advanced Event Triggering (AET)

The device supports Advanced Event Triggering (AET). This capability can be used to debug complex

problems as well as understand performance characteristics of user applications. AET provides the

following capabilities:

•

Hardware Program Breakpoints: specify addresses or address ranges that can generate events such

as halting the processor or triggering the trace capture.

•

Data Watchpoints: specify data variable addresses, address ranges, or data values that can generate

events such as halting the processor or triggering the trace capture.

•

Counters: count the occurrence of an event or cycles for performance monitoring.

•

State Sequencing: allows combinations of hardware program breakpoints and data watchpoints to

precisely generate events for complex sequences.

For more information on AET, see the following documents:

•

Using Advanced Event Triggering to Find and Fix Intermittent Real-Time Bugs application report

(Literature Number: SPRA753)

•

Using Advanced Event Triggering to Debug Real-Time Problems in High Speed Embedded

Microprocessor Systems application report (Literature Number: SPRA387)

8.5.2

Trace

The device supports Trace at the Cortex™-A8 and System levels. Trace is a debug technology that

provides a detailed, historical account of application code execution, timing, and data accesses. Trace

collects, compresses, and exports debug information for analysis. The debug information can be exported

to the Embedded Trace Buffer (ETB), or to the 5-pin Trace Interface (system trace only). Trace works in

real-time and does not impact the execution of the system.

For more information on board design guidelines for Trace Advanced Emulation, see the Emulation and

Trace Headers Technical Reference Manual (Literature Number: SPRU655).

8.5.3

IEEE 1149.1 JTAG

The JTAG (IEEE Standard 1149.1-1990 Standard-Test-Access Port and Boundary Scan Architecture)

interface is used for BSDL testing and emulation of the device. The TRST pin only needs to be released

when it is necessary to use a JTAG controller to debug the device or exercise the boundary scan

functionality of the device. For maximum reliability, the device includes an internal pulldown (IPD) on the

TRST pin to ensure that TRST is always asserted upon power up and the internal emulation logic of the

device is always properly initialized. JTAG controllers from Texas Instruments actively drive TRST high.

However, some third-party JTAG controllers may not drive TRST high but expect the use of a pullup

resistor on TRST. When using this type of JTAG controller, assert TRST to initialize the device after

powerup and externally drive TRST high before attempting any emulation or boundary-scan operations.

The main JTAG features include:

•

32KB embedded trace buffer (ETB)

•

5-pin system trace interface for debug

•

Supports Advanced Event Triggering (AET)

•

All processors can be emulated via JTAG ports

•

All functions on EMU pins of the device:

–

EMU[1:0] - cross-triggering, boot mode (WIR), STM trace

–

EMU[4:2] - STM trace only (single direction)

Peripheral Information and Timings

219

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