Pike Technical Manual
V5.2.0
37
FireWire
Whereas 1394a works in half duplex transmission, 1394b does full duplex trans-
mission. 1394b optimizes the usage of the bandwidth, as it does not need gaps
between the signals like 1394a. This is due to parallel arbitration, handled by
the bus owner supervisor selector (BOSS). For details see the following diagram:
Additional devices may be added up to the overall capacity of the bus, but
throughput at guaranteed minimum service levels is maintained for all devices
with an acknowledged claim on the bus. This deterministic feature is a huge
advantage for many industrial applications where robust performance is
required. This applies with applications that do not allow dropping images
within a specific time interval.
FireWire connection capabilities
FireWire
can connect together up to 63 peripherals in an acyclic network struc-
ture (hubs). It allows peer-to-peer device communication between digital cam-
eras, without using system memory or the CPU.
A
FireWire camera
can directly, via direct memory access (DMA), write into or
read from the memory of the computer with almost no CPU load.
FireWire
also supports multiple hosts per bus.
FireWire
requires only a cable
with the correct number of pins on either end (normally 6 or 9).
Figure 3: 1394b data transmission
Note
How to extend the size of an isochronous packet up to 11.000
byte at S800:
•
see register 0xF1000048, ADV_INQ_3, Max IsoSize [1] in
Table 155: Advanced register: Advanced feature inquiry
•
see Chapter
Cycle Sync: 1394b
Parallel arbitration, handled by BOSS, can eliminate gaps
