cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 280

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

13.0 ATM UTOPIA Interface
13.4 UTOPIA Level 2 Interface
13.4.2 UTOPIA Configuration Control
13.4.3 UTOPIA Level 2 Multi-Port Operation
13-8
Most options for the CN8237 UTOPIA interface are configured by control bits in
the CONFIG1 registers. However, the selection of UTOPIA Level 1 versus
Level 2 and of Master or Slave mode is controlled by the input pins FRCFG and
UTOPIA1. Normally, these inputs are hardwired as required by the system
design.
UTOPIA level 2, connecting it to +3.3 V selects UTOPIA Level 1. When
selecting UTOPIA Level 2 be sure to program the UTOPIA_MODE bit to logic
high to enable Cell level handshaking (octet level handshaking is not valid in
UTOPIA Level 2).
in
the CONFIG1 register. Setting this bit high selects cell-level handshaking. In this
mode, both the CN8237 and the selected port only begins a transfer when it has
room in its FIFO buffer’s for an entire cell. When UTOPIA Level 2 mode is
selected this bit MUST be set to logic high.
UTOPIA bus. By setting the MULTI_PHY bit of CONFIG1 to logic high, up to
eight devices can share the bus.
the UTOP16 bit of the CONFIG1 register. Setting this bit high enables a 16-bit data
path.
NOTE:
bus its port address must be programmed into the SLAVE_ADDR bits of
CONFIG1. Software must be aware that all CN8237s on the bus will default to
the same address, (00), and therefore, must reprogram each device to a unique
value.
The CN8237 supports up to eight multi-port operations as described in the
UTOPIA Level 2 Specification af-phy-0039.000 (see the ATM forum web site for
details: www.atmforum.com). Two primary functions are involved in transferring
data on the UTOPIA bus: polling the ports to determine which ones have data
ready and then selecting which port transfers its data. The receive side is
discussed below. The reader can refer to the above referenced web page for more
details.
Table
UTOPIA Level 1/Level 2—Tying the UTOPIA1 input pin to ground selects
Master/Slave selection—Controlled by the FRCFG hardware input as defined
Octet or Cell Handshaking—This is controlled by the UTOPIA_MODE bit in
Multi-port operations—By default, the CN8237 expects a single device on the
UTOPIA data bus width—The width of the UTOPIA data bus is selectable by
1.
2.
Slave address—When the CN8237 is configured as a slave on the UTOPIA
Number of ports on the bus—When running in multi-port mode the total
number of ports to poll is programmed into the NUM_PORTS bits of
CONFIG1.
Since port numbering begins with zero, this value equals the total number
of ports minus one.
13-1.
Mindspeed Technologies
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
™
28237-DSH-001-C
CN8237