
Philips Semiconductors
Product data
PDI1394P25BY
1-port 400 Mbps physical layer interface
2002 Oct 11
32
The sequence of events for a cancelled/null packet transmission is
as follows:
Transmit operation initiated. PHY asserts grant on the CTL lines
followed by idle to hand over control of the interface to the link.
Optional Idle cycle. The link may assert at most one idle cycle
preceding assertion of hold. This idle cycle is optional; the link is
not required to assert idle preceding Hold.
Optional Hold cycles. The link may assert Hold for up to 47 cycles
preceding assertion of idle. These hold cycle(s) are optional; the
link is not required to assert hold preceding Idle.
Null transmit termination. The null transmit operation is terminated
by the link asserting two cycles of idle on the CTL lines and then
releasing the interface and returning control to the PHY. Note that
the link may assert Idle for a total of 3 consecutive cycles if it
asserts the optional first idle cycle but does not assert hold. It is
recommended that the link assert 3 cycles of Idle to cancel a
packet transmission if no hold cycles are asserted. This ensures
that either the link or PHY controls the interface in all cycles.
After regaining control of the interface, the PHY shall assert at
least one cycle of Idle before any subsequent status transfer,
receive operation, or transmit operation.
SYSCLK
(a)
CTL0, CTL1
D0–D7
00
00
01
SV01763
Link Controls Ctl and D
PHY High-impedance Ctl and D Outputs
00
11
00
(b)
(d)
(e)
00
00
00
00
Figure 19.
Cancelled/Null Packet Transmission