cx28560 Mindspeed Technologies, cx28560 Datasheet - Page 63

• Manufacturer Part Number: cx28560
• Description: Hdlc Controller
• Manufacturer: Mindspeed Technologies

28560-DSH-001-B
3.0 Expansion Bus (EBUS)
The CX28560 provides an access to a local bus interface called the Expansion Bus
(EBUS), which provides a host processor to access any address in the peripheral
memory space on the EBUS. Although EBUS use is optional, the most notable
applications for the EBUS are the connections to peripheral devices, e.g., Bt8370/
Bt8398 T1/E1 framers, CN8398 (Octal DS1/E1 framers), and CX29503/M29513
BAM3/BAM3+ and CX29610 OptiPhy that are local to the CX28560’s serial port.
Similarly to the CN28500, but unlike previous generations of HDLC controllers
(CN8478/CN8474/CN8472), the CX28560 provides access to the EBUS through an
interface similar to a mailbox interface. This interface provides all the EBUS read and
write accesses to be carried over the PCI bus, allowing PCI bursts. This mechanism
improves the PCI use when multiple EBUS accesses are necessary for accessing the
configuration of peripheral devices. The PCI Function 1 is disabled. Therefore, the
CX28560’s EBUS service requests are capable of accepting or generating burst on the
PCI bus. However, the EBUS interface signals are not capable of performing burst.
Also, the CX28560 does not interface with EINT* signal of the EBUS. This signal
should be tied directly or via external logic to the PCI interrupt INTB*.
Figures 3-1
local microprocessor (MPU).
Figure 3-1. EBUS Functional Block Diagram with Local MPU
Address/Data
Clock
and
Mindspeed Technologies™
3-2
illustrate block diagrams of the EBUS interface with and without
Advance Information
Regenerated
Interface
Inverted
EBUS
and
Arbiter
Bus
Bus Arbitration
Address/Data
Control
Clock
Expansion
Local
Bus
Motorola
or T3/E3
Framers
Intel or
MPU
T1/E1
101302_005
3
-
1