• Two DWT comparators (addresses or a data) provide programmable start/
stop recording
• CoreSight compliant debug functionality
18.1.3 Modes of operation
The MTB_RAM and MTB_DWT functions do not support any special modes of
operation. The MTB_RAM controller, as a memory-mapped device located on the
platform's slave AHB system bus, responds based strictly on memory addresses for
accesses to its attached RAM array. The MTB private execution bus provides program
trace packet write information to the RAM controller. Both the MTB_RAM and
MTB_DWT modules are memory-mapped so their programming models can be
accessed.
All functionality associated with the MTB_RAM and MTB_DWT modules resides in the
core platform's clock domain; this includes its connections with the RAM array.
18.2 External signal description
The MTB_RAM and MTB_DWT modules do not directly support any external
interfaces.
The internal interfaces includes a standard AHB bus with a 32-bit datapath width from
the appropriate crossbar slave port plus the private execution trace bus from the processor
core. The signals in the private execution trace bus are detailed in the following table
taken from the ARM CoreSight Micro Trace Buffer documentation. The signal direction
is defined as viewed by the MTB_RAM controller.
Table 18-1. Private execution trace port from the core to MTB_RAM
Signal
Direction
Description
LOCKUP
Input
Indicates the processor is in the Lockup state. This signal is driven LOW for cycles
when the processor is executing normally and driven HIGH for every cycle the
processor is waiting in the Lockup state. This signal is valid on every cycle.
IAESEQ
Input
Indicates the next instruction address in execute, IAEX, is sequential, that is non-
branching.
IAEXEN
Input
IAEX register enable.
IAEX[30:0]
Input
Registered address of the instruction in the execution stage, shifted right by one
bit, that is, PC >> 1.
ATOMIC
Input
Indicates the processor is performing non-instruction related activities.
EDBGRQ
Output
Request for the processor to enter the Debug state, if enabled, and halt.
Chapter 18 Micro Trace Buffer (MTB)
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
Freescale Semiconductor, Inc.
227