IEEE1394 -- New Interface for the Digital Network Age
The IEEE 1394 standard defines a serial interface ideal for the digital age. This inexpensive, easy-to-use and high-speed
bus easily handles multimedia bandwidth requirements and provides a universal interface for a variety of devices. By
allowing seamless data exchange between devices such as workstations, personal computers and digital televisions, VCRs,
camcorders and set-top boxes, it enables a new generation of computers and consumer electronic devices to operate in a
common environment (Figures 1 and 2). Industry analysts predict a surge in IEEE 1394 product shipments and expect the market
to grow from less than 2 million devices in 1997 to more than 460 million by 2011.
Figure 1. IEEE 1394 Applications
Figure 2. Digital Home Network Concept
Originally developed as an interface to replace SCSI, IEEE 1394 offers bi-directionality, high data transfer rates and
isochronous data transfers. It provides "hot plug" capability -- the ability to connect or disconnect equipment with the
power on. It also enables devices that require audio, video and control signals to be connected with a single cable.
Sony was among the first to practically apply the advantages of the IEEE 1394 standard including its scalability, real-time
data processing, simple connections and low cost. In 1995, Sony released the DCR-VX1000 digital video camcorder, the first
commercial product to feature an IEEE 1394 interface. The company was also among the first to develop LSI products to
support this standard. Sony offers or is developing IEEE 1394 LSIs for a variety of products including personal computers,
set-top boxes, digital video camcorders, hard disk drives, CD-ROM drives and DVD-ROM drives. These LSIs greatly expand the
ability to connect traditional consumer electronics equipment such as digital video cassette recorders and set-top boxes
to personal computers.
IEEE 1394 Cable
To make high-speed serial interfaces easy to use, the IEEE 1394 standard adopts an extremely simple cable with a flexible
structure. Using this cable, the wide connectors and multi-conductor cables that are now standard in personal computer
interfaces are no longer required (Figures 3.1 and 3.2).
4-pin Cable
6-pin Cable
Figures 3.1 & 3.2 IEEE 1394 Connector Styles
Data transfer is handled by a shielded double twisted pair cable that is driven by low-amplitude differential signals
(Figure 4). During data transfer, a clock signal is generated automatically by converting the data into two signals:
the data itself and a strobe signal that supplements the data (Figure 5). This eliminates the need for the high-speed
phase lock loop (PLL) circuits required by other interfaces at both the transmit and receive sides of the communications
channel. As a result, systems can be constructed inexpensively. In addition, since the interface includes a power line
in the cable, power can be supplied directly to low-power devices.
Figure 4. 6-pin Cable Configuration
Figure 5. DS-Link Coding Scheme
Designed to connect various peripherals in IEEE 1394 environments, Sony's family of LSIs are shown in Table 1.
Table 1. Sony LSI Product Family
PCI Bus Link Layer LSI
Sony's CXD1947Q is a PCI bus link layer LSI that conforms to the IEEE 1394-1995 serial
bus standard. Since it includes a built-in PCI bus bridge, it can be connected directly to the PCI bus. It also includes
a six-channel DMA circuit for high-performance data transfer. Systems that support the IEEE standard can easily be
implemented by using the CXD1947Q and the CXD1944R LSIs.
MPEG-2 DVB and DSS Link Layer LSI
The CXD1948R link layer LSI conforms to the IEEE 1394-1995 standard. It supports MPEG-2
streams for set-top boxes, digital television, digital video broadcast (DVB) and digital satellite system (DSS)
applications. This LSI adds a time stamp and common isochronous protocol (CIP) headers to each packet during
transmission, and can automatically recover time stamps during reception. It supports data transfer rates of 100 and
200Mbps and supports the DVB (188-byte) and DSS (130-/140-byte) transport streams. Providing an asynchronous host
interface and an isochronous TPS interface, it also includes an insert FIFO to allow isochronous transfers from the
host interface (Figure 6).
Figure 6. CXD1948R Block Diagram
SBP-2 Link/Transaction Layer LSI
The CXD3220R link/transaction layer LSI conforms to the SBP-2 (Serial Bus Protocol 2)
standard (Figure 7). This LSI can connect any type of storage device -- including hard disk, DVD-ROM, CD-ROM and streaming
tape drives -- to an IEEE 1394 digital interface.
Figure 7. CXD3220R Block Diagram
This LSI includes an asynchronous data page circuit to automatically generate SBP-2 packets. Unlike previous generation
products which implement the transaction layer in software, the highly-integrated CXD3220R
implements it in hardware. The device supports data transfer rates of 100 and 200Mbps. It includes three large
capacity FIFOs: a 2KB FIFO for data transfers, a 96-byte FIFO for asynchronous transfers and a 156-byte FIFO for reception.
The CXD3220R provides 8- and 16-bit interfaces for both CPU and transport data, making it
ideal for native IEEE 1394 drives which many computer manufacturers support as serial SCSI.
Future Developments
IEEE 1394 is destined to become the network standard of the future for supporting digital content. Sony is committed to
the practical application of this standard through larger capacity, higher speed, lower power and even more compact
products. The company is dedicated to developing IEEE 1394-compliant LSIs that support an even wider range of applications,
integrating this technology with a broad variety of system chipsets and developing products that support data transfer
rates for emerging applications requiring 400Mbps and higher (Figure 8).
Figure 8. IEEE 1394 LSI Roadmap
In the future, IEEE 1394 may become the basis of home networking and a replacement for PCI and IDE buses in personal
computers. Currently there are several groups actively discussing extensions to IEEE 1394, including the IEEE 1394a and
1394b working groups. Sony is taking an active role in these standards activities and is committed to creating a broad
spectrum of IEEE 1394-based products.
