| Firewire IEEE-1394
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| Firewire IEEE-1394
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1394 Questions & Answers : GENERAL
Q. What is 1394?
A. 1394 is an IEEE standard for a high-speed, low cost serial bus that has been developed by an IEEE committee. Among other things, 1394 is designed to be a global interconnect, eliminating the need for many different I/O interconnects resulting in port integration and board space consolidation. This will result in a system-level cost reduction.
Q. How does Apple fit in?
A. Apple wanted an open architecture, so they introduced their Firewire technology to the committee.
Q. Is the standard stable?
A. Yes, the standard was adopted by IEEE in December 1995. The hardware portions had not been changed from the 8.0 v2 draft. The standard currently specifies speeds of 100, 200 and 400 Mbits/second. There are efforts to create speed improvements to 800 and multi-Gigabit speeds. For a copy of the IEEE approved standard, it can be purchased from IEEE Standards Department, specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus, 420 pages [1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can be ordered by calling (800)678-IEEE.
Q. What 1394 connector specifications are available?
A. The connector specifications are located in the IEEE 1394-1995 standard. This document contains both cable as well as connector mechanical drawings. For a copy of the IEEE approved standard, it can be purchased from IEEE Standards Department, specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus, 420 pages [1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can be ordered by calling (800)678-IEEE.
Q. Where can I find out general system level information on 1394?
A. The best information that is currently available regarding system-level issues is the actual IEEE spec itself.
1394 Questions and Answers : DATARATES/PERFORMANCE
Q. What is the maximum transmission rate?
A. 1394 is defined to support - 100, 200, and 400 m/bits per second data throughput rates. The committee decided to define these speeds up front so that future speed enhancements can be quickly implemented. There are efforts to expand the standard to include 800 and multi-Gigabit speed improvements.
Q. Is the transfer rate of the 1394 scalable?
A. Yes, 100, 200, and 400 megabits per second nodes can all be supported in the same topology.
Q. Will this require a different chip set for each speed?
A. Yes. However, since 1394 is dynamically designed, there is no need to have every node operating at the same speed. If you add a new node, the topology will reconfigure itself to incorporate the new node.
Q. How does the sustainable bandwidth differ between isochronous and asynchronous transactions?
A. The two major differences between the two types of transaction which affect the sustained throughput are that isochronous transactions do not involve 'acknowledges' and isochronous gaps are of shorter duration than 'subaction gaps'.
1394 Questions & Answers : CABLE/CONNECTOR
Q. Is the shield connected to ground?
A. Yes, both the internal and external shield are connected to ground.
Q. How many power lines are incorporated in 1394?
A. There are two power lines that are used in the 1394 cable.
Q. What type of cable is used with 1394?
A. It is a six wire, shielded twisted-pair cable.
Q. What 1394 connector specifications are available?
A. The connector specifications are located in the IEEE 1394-1995 standard. This document contains both cable as well as connector mechanical drawings. For a copy of the IEEE approved standard, it can be purchased from IEEE Standards Department, specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus, 420 pages 1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can be ordered by calling (800)678-IEEE.
1394 Questions & Answers : SYSTEMS/APPLICATIONS
Q. On the PC side, does it matter what internal bus you are using?
A. No, as long as an interface to the bus is present.
Q. What about a PCI bus?
A. You can take full advantage of 1394 by using this local bus. At this time, it seems that PCI is the way most companies are going. Both PCI and 1394 are emerging technologies and it makes sense to link them together. Please see the Technical Overview for more information on TI solutions for 1394 bus and PCI bus interconnection.
Q. Does 1394 have interactive video capability?
A. Yes
Q. Could 1394 be a cable to TV link with many other possibilities?
A. Yes, we now see many opportunities for utilizing 1394 that we did not see initially. Also, 1394 will make a big difference in the multimedia market by bringing the price down and providing many features beneficial to this market.
Q. Can you connect a device to the PC while operating another unit?
A. Yes, and this is truly an advantage for the people interested in a "plug-and-play" environment.
Q. Is 1394 multi-point - does it function like a bus?
A. No, 1394 is a point-to-point bus which has many characteristics of a multi-point bus.
Q. Does a system require any other chips other than a Physical Layer device such as TSB11C01 and a LINK layer controller such as the TSB12C01A to implement a system?
A. Not to implement, or be compliant to, 1394.
There will normally, however, be some logic needed to hook these chips into the rest of the application or system. The requirement for additional chips (in addition to the link layer and physical layer chips) depends on the application. For example, one customer is using a 32-bit processor to send & receive information from the FIFOs on the TSB12C01A Link. Another possibility is to use a DSP such as the TMS320C52 to control the link layer device. Please see the Technical Overview for more information on TI solutions.
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