AN2866 Freescale Semiconductor / Motorola, AN2866 Datasheet - Page 12

• Manufacturer Part Number: AN2866
• Description: Migrating from the MC68332 to the ColdFire MCF523x
• Manufacturer: Freescale Semiconductor / Motorola

Device Differences
Processor Unit (TPU) to address complex timing problems in embedded control applications. Since the
TPU is a microcontroller itself, it can perform timing tasks with little or no CPU intervention, thus
improving overall system performance. The eTPU on the MCF523x is an enhanced version of TPU. These
enhancements include a more powerful processor, more channels, and an increase in Parameter RAM and
code memory, allowing for more functionality and increased performance. Consequently, the eTPU
significantly increases overall system performance. The MCF523x is the first ColdFire device to include
an eTPU module.
2.4.1.1.1
One of the primary enhancements of the eTPU is a more powerful processor that is capable of efficiently
handling high-level C code. This allows for greater range of functionality at a higher level of performance.
Although there is no compatibility at the microcode level, the eTPU maintains several features of older
TPU versions and is conceptually almost identical. As most TPU users utilized the standard set of TPU
functions on the 68332, this identical functionality and more will also be provided on the eTPU. Therefore,
porting is not a major concern. The eTPU library is a superset of the standard TPU library functions
modified to take advantage of enhancements in the eTPU. These, along with a C compiler and source code
from the Freescale library, make it is possible for the eTPU to support the user’s own function
development.
For a list of eTPU functions, please refer to the eTPU Reference Manual (ETPURM).
2.4.1.1.2
The number of timer channels for the eTPU increased from 16 to 32, which allows more control with a
single eTPU. The code memory increased from 2 KB to 6 KB, and the parameter RAM also increased
from 200 B to 1.5 KB.
Another enhancement is that now the eTPU supports more interrupt types. Not only can each eTPU
channel generate an interrupt, but there is also one global interrupt.
With respect to the eTPU resolution of performing timing tasks, the eTPU Core has a resolution of
13.33 ns, and the eTPU Timebases have a resolution of 26.66 ns at 150 MHz. Compared to 120 ns and
240 ns at 16.67 on the 68332, respectively, it shows a 10x improvement.
For more detailed information, please refer to The Essentials of the Enhanced Time Processing Unit
(AN2353).
2.4.1.2
The MC68332 has 2 Kbytes of SRAM while the MCF523x has 64 Kbytes. For both devices, the base
address of the SRAM is programmable via a base address register. The primary difference between the
SRAM is that the MC68332 supports SRAM data retention during power down by supplying voltage to
the V
12
STBY
pin; while, the MCF523x does not support standby power for the SRAM.
SRAM
Software Considerations
Hardware Consideration
Migrating from the MC68332 to the ColdFire
®
MCF523x, Rev. 1.0
Freescale Semiconductor