MMC2107 Datasheet, PDF (573/618 Pages) –

Freescale Semiconductor, Inc.
JTAG Test Access Port and OnCE
Functional Description
21.14.8.1 OnCE Trace Counter
The OnCE trace counter register (OTC) is a 16-bit counter that allows
more than one instruction to be executed in real time before the device
returns to debug mode. This feature helps the software developer debug
sections of code that are time-critical. The trace counter also enables the
user to count the number of instructions executed in a code segment.
DSI
DSO
DSCK
OnCE TRACE COUNTER
END
OF
INSTRUCTION
DEC
COUNT = 0
ISTRACE
Figure 21-12. OnCE Trace Logic Block Diagram
The OTC register can be read, written, or cleared through the OnCE
serial interface. If N instructions are to be executed before entering
debug mode, the trace counter should be loaded with N – 1. N must not
equal zero unless the sequential breakpoint control capability is being
used. In this case a value of zero (indicating a single instruction) is
allowed.
A hardware reset clears the OTC.
MMC2107 – Rev. 2.0
MOTOROLA
JTAG Test Access Port and OnCE
For More Information On This Product,
Go to: www.freescale.com
Technical Data
573