FireWire is the commercial name given by Apple in a multiplexed serial interface, also known as the standard IEEE 1394 and also known under the name of interface i.LINKtrade name used by Sony. He is a computer bus conveying both data and signals commands of the different connected devices.
You can use it to connect all kinds of fond bandwidth devices and who require the data rate to be stable, particularly in the context of hard drives and digital camcorders. She can supply a device, as well as to connect 63 peripherals by bus, connection/disconnection is done while the system is running.
You can connect up to 1 024 bus through gateways.
FireWire was designed for Apple Computer in 1986. It has become a standard in 95. As a result, other manufacturers, including Sony and Texas Instrument contributed to its design.
FireWire uses a time multiplexing : time is sliced of 125 microseconds (8 000 cycles per second), the data is divided into packets. In each band are first transmitted packets isochronous (sound, video) then the asynchronous packets (data). This system guarantees bandwidth for the video stream avoiding jerking effects and further loss of quality.
Isochronous streams are identified by a channel (maximum : 63), and must all have a package for every;
Once the Isochronous packets issued the rest of the cycle is used for asynchronous packets identified not by a channel but by ID transmitter device and ID of the recipient device.
FireWire 400 connector
FireWire is said Hot Plug (hot plug); the connection or the disconnection of a device raises an event bus reset at all other devices : so we know at any time which is present on the bus.
Each bus reset devices receive a number from 0 to 62; who has the biggest number was elected leader of the bus or root, and it is he who is responsible for the beginning of the cycles of 125 microseconds.
Any device can be root Unlike USB where this role is performed by the host to which the devices are connected.
Although he most often serve to connect hard disks or camcorders to make video montages, or to capture audio data via its external, port cards FireWire can be, for specific needs, used to connect two machines on a network.
It appears therefore as part of devices in network connections in Windows XP and as network interface on systems using a Linux or UNIX kernel.
6-pin format allows feeding devices and 4-pin format is without power
Two separate pinouts are available in s400 and s800 : 6-pin format allowing feeding devices and format 4 pins without power. The format to four pins is that laptops and camcorders with mini bands DV.
In s800 the connectors have 9 pins. s400 and s800 are compatible : you can connect a device s800 with a s400 using a cable 9 pin to 6 pin.
The most common cable consists of twisted copper wires. The maximum length for all protocols FireWire is of 4,5 m. There is also a transmission by optical fiber, very expensive but to achieve 100 m.
|1||VCC : 30 V|
|3||TPB - : (twisted pair B) differential signals|
|4||+ TPB : (twisted pair B) differential signals|
|5||TPA - : (twisted pair) differential signals|
|6||+ TPA : (twisted pair) differential signals|
FireWire allows theoretical flow reaching :
|100 Mb/s in version 1||. (IEEE 1394a-s100)|
|200 Mb/s in version 1||. (IEEE 1394a-s200)|
|400 Mb/s in version 1||. (IEEE 1394a-s400)|
|800 Mb/s in version 2. (IEEE 1394b-s800)|
|1 200 Mb/s in version 2. (IEEE 1394b-s1200)|
|1 600 Mb/s in version 2. (IEEE 1394b-s1600)|
|3 200 Mb/s in version 2. (IEEE 1394b-s3200)|
The standard IEEE 1394b can also be called FireWire Gigabit,
or Firewire 800.
The s1600 and s3200 have been adopted by theIEEE in August 2008.