by holding critical DSP code and parameters in the cache for immediate
availability. The microprocessor also implements an on-chip MMU with a
TLB, making the it fully compliant with the requirements of real time
operating systems.
Memory and IO Controller
The RC32355 incorporates a flexible memory and peripheral device
controller providing support for SDRAM, Flash ROM, SRAM, dual-port
memory, and other I/O devices. It can interface directly to 8-bit boot
ROM for a very low cost system implementation. It enables access to
very high bandwidth external memory (300 MB/sec peak) at very low
system costs. It also offers various trade-offs in cost / performance for
the main memory architecture. The timers implemented on the RC32355
satisfy the requirements of most RTOS.
DMA Controller
The DMA controller off-loads the CPU core from moving data among
the on-chip interfaces, external peripherals, and memory. The DMA
controller supports scatter / gather DMA with no alignment restrictions,
appropriate for communications and graphics systems.
TDM Bus Interface
The RC32355 incorporates an industry standard TDM bus interface
to directly access external devices such as telephone CODECs and
quality audio A/Ds and D/As. This feature is critical for applications, such
as cable modems and xDSL modems, that need to carry voice along
with data to support Voice Over IP capability.
Ethernet Interface
The RC32355 contains an on-chip Ethernet MAC capable of 10 and
100 Mbps line interface with an MII interface. It supports up to 4 MAC
addresses. In a SOHO router, the high performance RC32300 CPU core
routes the data between the Ethernet and the ATM interface. In other
applications, such as high speed modems, the Ethernet interface can be
used to connect to the PC.
USB Device Interface
The RC32355 includes the industry standard USB device interface to
enable consumer appliances to directly connect to the PC.
ATM SAR
The RC32355 includes a configurable ATM SAR that supports a
UTOPIA level 1 or a UTOPIA level 2 interface. The ATM SAR is imple-
mented as a hybrid between software and hardware. A hardware block
provides the necessary low level blocks (like CRC generation and
checking and cell buffering) while the software is used for higher level
SARing functions. In xDSL modem applications, the UTOPIA port inter-
faces directly to an xDSL chip set. In SOHO routers or in a line card for a
Layer 3 switch, it provides access to an ATM network.
Enhanced JTAG Interface for ICE
For low-cost In-Circuit Emulation (ICE), the RC32300 CPU core
includes an Enhanced JTAG (EJTAG) interface. This interface consists
of two operation modes: Run-Time Mode and Real-Time Mode.
The Run-Time Mode provides a standard JTAG interface for on-chip
debugging, and the Real-Time Mode provides additional status pins—
PCST[2:0]—which are used in conjunction with the JTAG pins for real-
time trace information at the processor internal clock or any division of
the pipeline clock.
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79RC32355
Thermal Considerations
The RC32355 consumes less than 2.5 W peak power. It is guaran-
teed in a ambient temperature range of 0° to +70° C for commercial
temperature devices and - 40° to +85° for industrial temperature
devices.
Revision History
March 29, 2001:
Initial publication.
September 24, 2001:
Removed references to DPI interface.
Removed references to “edge-triggered interrupt input” for GPIO pins.
Changed 208-pin package designation from DP to DH.
October 10, 2001:
Revised AC timing characteristics in Tables 5, 6,
7, 8, 10, 12, and 15. Revised values in Table 18, “DC Electrical Charac-
teristics”; Table 20, “RC32355 Power Consumption”; and Figure 23,
“Typical Power Usage.” Changed data sheet from Preliminary to Final.
October 23, 2001:
Revised Figure 23, “Typical Power Usage.”
November 1, 2001:
Added Input Voltge Undershoot parameter and 2
footnotes to Table 21.
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November 1, 2001
79RC32355
Pin Description Table
The following table lists the functions of the pins provided on the RC32355. Some of the functions listed may be multiplexed onto the same pin.
To define the active polarity of a signal, a suffix will be used. Signals ending with an “N” should be interpreted as being active, or asserted, when at
a logic zero (low) level. All other signals (including clocks, buses and select lines) will be interpreted as being active, or asserted when at a logic one
(high) level.
Note:
The input pads of the RC32355 do not contain internal pull-ups or pull-downs. Unused inputs should be tied off to appropriate levels.
This is especially critical for unused control signal inputs (such as BRN) which, if left floating, could adversely affect the RC32355’s opera-
tion. Also, any input pin left floating can cause a slight increase in power consumption.
Name
System
CLKP
COLDRSTN
RSTN
I
I
I/O
Input
STI
1
Low Drive
with STI
System Clock input.
This is the system master clock input. The RISCore 32300 pipeline frequency is a multiple (x2, x3, or
x4) of this clock frequency. All other logic runs at this frequency or less.
Cold Reset.
The assertion of this signal low initiates a cold reset. This causes the RC32355 state to be initialized, boot
configuration to be loaded, and the internal processor PLL to lock onto the system clock (CLKP).
Reset.
This bidirectional signal is either driven low or tri-stated, an external pull-up is required to supply the high state. The
RC32355 drives RSTN low during a reset (to inform the external system that a reset is taking place) and then tri-states it.
The external system can drive RSTN low to initiate a warm reset, and then should tri-state it.
Type I/O Type
Description
SYSCLKP
O
High Drive
System clock output.
This is a buffered and delayed version of the system clock input (CLKP). All SDRAM transactions
are synchronous to this clock. This pin should be externally connected to the SDRAMs and to the RC32355 SDCLKINP pin
(SDRAM clock input).
[21:0] High
Memory Address Bus.
26-bit address bus for memory and peripheral accesses. MADDR[20:17] are used for the
SODIMM data mask enables if SODIMM mode is selected.
Drive
[25:22] Low MADDR[22] Primary function: General Purpose I/O, GPIOP[27].
Drive with MADDR[23] Primary function: General Purpose I/O, GPIOP[28].
MADDR[24] Primary function: General Purpose I/O, GPIOP[29].
STI
MADDR[25] Primary function: General Purpose I/O, GPIOP[30].
Memory and Peripheral Bus
MADDR[25:0]
O
MDATA[31:0]
BDIRN
BOEN[1:0]
I/O
O
O
High Drive
Memory Data Bus.
32-bit data bus for memory and peripheral accesses.
High Drive
External Buffer Direction.
External transceiver direction control for the memory and peripheral data bus, MDATA[31:0]. It
is asserted low during any read transaction, and remains high during write transactions.
High Drive
External Buffer Output Enable.
These signals provide two output enable controls for external data bus transceivers on
the memory and peripheral data bus, MDATA. BOEN[0] is asserted low during external device read transactions. BOEN[1]
is asserted low during SDRAM read transactions.
STI
Low Drive
STI
External Bus Request.
This signal is asserted low by an external master device to request ownership of the memory and
peripheral bus.
External Bus Grant.
This signal is asserted low by RC32355 to indicate that RC32355 has relinquished ownership of the
local memory and peripheral bus to an external master.
Wait or Transfer Acknowledge.
When configured as wait, this signal is asserted low during a memory and peripheral
device bus transaction to extend the bus cycle. When configured as transfer acknowledge, this signal is asserted low dur-
ing a memory and peripheral device bus transaction to signal the completion of the transaction.
BRN
BGN
WAITACKN
I
O
I
CSN[5:0]
O
Device Chip Select.
These signals are used to select an external device on the memory and peripheral bus during device
[3:0]
High Drive transactions. Each bit is asserted low during an access to the selected external device.
CSN[4] Primary function: General purpose I/O, GPIOP[16].
CSN[5] Primary function: General purpose I/O, GPIOP[17].
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