AN2798 Freescale Semiconductor / Motorola, AN2798 Datasheet - Page 4

• Manufacturer Part Number: AN2798
• Description: Migrating from the MPC855T to the MPC885
• Manufacturer: Freescale Semiconductor / Motorola

The MPC855T
4 The MPC855T
The MPC855T PowerQUICC is a 0.32 µm version of the MPC8XX PowerQUICC family of communications
microprocessors. The MPC855T has a core voltage of 3.3 V and an I/O voltage of 3.3 V, with 5V-compatibility. The
MPC855T supports a maximum core speed of 80 MHz and a maximum external bus speed of 66 MHz.
The MPC855T incorporates the same embedded MPC8XX processor core and similar CPM and SIU as the
MPC8XX family. The MPC855T features one 10/100 Fast Ethernet controller module. The CPM supports one SCC
(SCC1), two SMCs (SMC1 and SMC2), SPI and I
UART, and transparent protocols.
5 Similarities and Differences between the MPC855T and
The following sections discuss pinout and memory mapping differences for the MPC855T and the MPC885.
4
the MPC885
Fast Ethernet
Media Access
Embedded
Controller
Processor
MPC8xx
Base-T
Control
10/100
FIFOs
DMAs
Core
MII
Load/Store
Instruction
Bus
Bus
Parallel Interface Port
Migrating from the MPC855T to the MPC885, Rev. 0
4 Baud Rate
and UTOPIA
Generators
Parallel I/O
SCC2
Instruction Cache
Instruction MMU
32-Entry DTLB
32-Entry ITLB
Data Cache
Data MMU
Figure 2. MPC855T Block Diagram
4-Kbyte
4-Kbyte
Timers
Timers
2
Time Slot Assigner
4
C. The SCC can support 802.3 Ethernet, ATM, HDLC/SDLC,
Time Slot Assigner
32-Bit RISC Controller
Controllers
Interrupt
and Program
Unified
ROM
Bus
Serial Interface
Serial Interface
Dual-Port RAM
SMC1*
8-Kbyte
System Interface Unit (SIU)
Bus Interface
Internal
PCMCIA-ATA Interface
SMC2
Unit
Memory Controller
System Functions
Real-Time Clock
Independent
Bus Interface
SPI
SPI
10 Virtual
Channels
Serial*
External
DMA
and
Unit
2
Freescale Semiconductor
I
I
2
2
C
C