AN2866 Freescale Semiconductor / Motorola, AN2866 Datasheet - Page 18

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

Device Differences
2.4.2
There are seven modules on the MCF523x that have no functional equivalent on the MC68332. They are
the Fast Ethernet controller (FEC), Cache, FlexCAN, SDRAM controller, Direct Memory Access
controller (DMA), I
following sections give a high-level description of these modules. The only migration issue with these
modules is whether or not they could be of use in an existing design when porting to the MCF523x. If an
existing MC68332 design has similar functionality implemented off-chip, then it may be beneficial to
eliminate the external components and bring the functionality on chip.
2.4.2.1
The MCF523x’s integrated Fast Ethernet controller (FEC) performs the full set of IEEE 802.3/Ethernet
CSMA/CD media access control and channel-interface functions. The FEC supports connection and
functionality for either 10 or 100 Mbps 802.3 media independent interface (MII), with either half or full
duplex capability. It requires an external transceiver (PHY) to complete the interface to the media. There
are on-chip transmit and receive FIFOs, a built-in dedicated DMA controller, and memory-based flexible
descriptor rings.
2.4.2.2
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
18
Normal mode with crystal reference
Normal mode with external clock reference
(oscillator)
1:1 Mode
Bypass mode
Input clock frequency
System clock frequency
System clock to CLKOUT ratio
New/Additional Modules
Fast Ethernet Controller (FEC)
Cache
bypass and 1:1 mode
normal mode
bypass mode
normal mode
Feature
2
C, and cryptographic hardware accelerators (SKHA, MDHA, and RNG). The
Migrating from the MC68332 to the ColdFire
Table 6. MC68332 and MCF523x PLL Differences
130kHz-25MHz
Clock frequency options
25kHz-50kHz
MC68332
0-25MHz
0-25MHz
16:1, 8:1
Operating modes
—
—
√
√
24-75MHz
24-75MHz
24-75MHz
MCF523x
8-25MHz
1:1
®
√
√
√
√
MCF523x, Rev. 1.0
Comments
Freescale Semiconductor