FireWire
PIKE Technical Manual
V5.0.0
36
Image transfer via 1394a and 1394b
Technical detail
1394a
1394b
Transmission mode
Half duplex (both pairs needed)
400 Mbit/s data rate
aka: a-mode, data/strobe (D/S)
mode, legacy mode
Full duplex (one pair needed)
1 Gbit/s signaling rate, 800
Mbit/s data rate
10b/8b coding (Ethernet), aka:
b-mode (beta mode)
Devices
Up to 63 devices per network
Number of cameras
Up to 16 cameras per network
Number of DMAs
4 to 8 DMAs (parallel) cameras / bus
Real time capability
Image has real time priority
Available bandwidth acc. IIDC
(per cycle 125 µs)
4096 bytes per cycle
~ 1000q @ 400 Mbit/s
8192 bytes per cycle
~ 2000q @ 800 Mbit/s
(@1 GHz clock rate)
For further detail read Chapter
Max. image bandwidth
31.25 MByte/s
62.5 MByte/s
Max. total bandwidth
~45 MByte/s
~85 MByte/s
Number of busses
Multiple busses per PC
limit: PCI bus
Multiple busses per PC
limit: PCI (Express) bus
CPU load
Almost none for DMA image transfer
Gaps
Gaps negatively affect asynchro-
nous performance of widespread
network (round trip delay),
reducing efficiency
No gaps needed, BOSS mode for
parallel arbitration
Table 4: Technical detail comparison: 1394a and 1394b
Note
The bandwidth values refer to the fact:
1 MByte = 1024 kByte
