MOTOROLA
MCF523x Integrated Microprocessor Hardware Specifications
11
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Features
The on-chip breakpoint resources include a total of 6 programmable registers—a set of address registers
(with two 32-bit registers), a set of data registers (with a 32-bit data register plus a 32-bit data mask register),
and one 32-bit PC register plus a 32-bit PC mask register. These registers can be accessed through the
dedicated debug serial communication channel or from the processor’s supervisor mode programming
model. The breakpoint registers can be configured to generate triggers by combining the address, data, and
PC conditions in a variety of single or dual-level definitions. The trigger event can be programmed to
generate a processor halt or initiate a debug interrupt exception.
To support program trace, the Version 2 debug module provides processor status (PST[3:0]) and debug data
(DDATA[3:0]) ports. These buses and the PSTCLK output provide execution status, captured operand data,
and branch target addresses defining processor activity at the CPU’s clock rate.
The integration of the eTPU on the MCF523x family marks the first time that ColdFire and Nexus debug
subsystems have been present in a single device. The eTPU’s Nexus functionality has been merged into the
standard ColdFire debug model. This includes access to the eTPU Nexus debug registers via the standard
ColdFire BDM serial interface or the processor WDEBUG instruction and run/halt cross triggering
capability between eTPU Nexus and ColdFire BDM.
1.3.6
JTAG
The MCF523x supports circuit board test strategies based on the Test Technology Committee of IEEE and
the Joint Test Action Group (JTAG). The test logic includes a test access port (TAP) consisting of a 16-state
controller, an instruction register, and three test registers (a 1-bit bypass register, a 330-bit boundary-scan
register, and a 32-bit ID register). The boundary scan register links the device’s pins into one shift register.
Test logic, implemented using static logic design, is independent of the device system logic.
The MCF523x implementation can do the following:
Perform boundary-scan operations to test circuit board electrical continuity
Sample MCF523x system pins during operation and transparently shift out the result in the
boundary scan register
Bypass the MCF523x for a given circuit board test by effectively reducing the boundary-scan
register to a single bit
Disable the output drive to pins during circuit-board testing
Drive output pins to stable levels
1.3.7
On-chip Memories
1.3.7.1
Cache
The 8-Kbyte cache can be configured into one of three possible organizations: an 8-Kbyte instruction cache,
an 8-Kbyte data cache or a split 4-Kbyte instruction/4-Kbyte data cache. The configuration is
software-programmable by control bits within the privileged Cache Configuration Register (CACR). In all
configurations, the cache is a direct-mapped single-cycle memory, organized as 512 lines, each containing
16 bytes of data. The memories consist of a 512-entry tag array (containing addresses and control bits) and
a 8-Kbyte data array, organized as 2048
× 32 bits.
If the desired address is mapped into the cache memory, the output of the data array is driven onto the
ColdFire core's local data bus, completing the access in a single cycle. If the data is not mapped into the tag
memory, a cache miss occurs and the processor core initiates a 16-byte line-sized fetch. The cache module