
TM1100 Preliminary Data Book
Philips Semiconductors
10-16
PRELIMINARY INFORMATION
File: pci.fm5, modified 7/23/99
10.8.1
Single-Data-Phase Operations
When the DSPCPU reads or writes PC memory, the PCI
transaction has only a single data phase. A typical sin-
gle-data-phase
read
operation
is
illustrated
in
asserts the frame# signal to indicate that the transaction
has begun and that an address and command are stable
on ad and c/be#, respectively.
TM1100 then releases the ad bus, deasserts frame#, as-
serts irdy#, asserts byte enables on c/be#, and waits for
the target to claim the transaction by asserting devsel#.
The target asserts trdy# to signal the master that the ad
bus contains stable data. The assertion of trdy# causes
the initiator (TM1100 in this case) to sample the ad bus
data and deassert irdy# to complete the single-data-
phase read transaction.
eration. The operation begins as with the read: TM1100
asserts the frame# signal and drives the ad bus with the
target address and drives the command onto the c/be#
bus.
The operation continues when TM1100 deasserts
frame#, asserts irdy#, and drives the byte enables as be-
fore, but it also drives the data to be written on the ad
bus. The target device asserts devsel# to claim the trans-
action. Eventually, the target asserts trdy# to signal that
it is sampling the data on the ad bus. TM1100 continues
to drive the data on the ad bus until after the target deas-
serts trdy#, which completes the write operation.
10.8.2
Multi-Data-Phase Operations
As with the single-data-phase operations, DMA opera-
tions begin with the assertion of frame# and valid ad-
target knows a burst is requested because frame# re-
mains asserted when irdy# becomes asserted.
ceiving the burst from TM1100. The target asserts
devsel# and trdy# simultaneously. The trdy# signal re-
mains asserted while TM1100 sends a new word of data
on each PCI clock cycle. The burst operation shown is a
16-word burst transfer. Since only the starting address is
sent by the initiator, both initiator and target must incre-
ment source and destination addresses during the burst.
The initiator signals the end of the burst of data in
last word (or partial word) of data is transferred in the
clock cycle after frame# is deasserted. Finally, the target
acknowledges the last data phase by deasserting trdy#
and devsel#.
transfers. The ICP is capable of exploiting the high band-
width available with back-to-back DMA operations when
it is writing image data to a frame buffer on a PCI video
card.
granted to TM1100 until at least the beginning of the sec-
ond DMA burst operation. For as long as bus ownership
is granted to TM1100 and the ICP has queued requests
for data transfer, the PCI interface will perform back-to-
back DMA operations. If the target eventually becomes
unable to accept more data, it signals a disconnect
TM1100’s PCI interface. The PCI interface remembers
where the DMA burst was interrupted and attempts to re-
start from that point after two bus clocks.
Table 10-21. TM1100 PCI Commands as Target
TM1100 Responds To
TM1100 Ignores
Conguration read
Conguration write
Memory read
Memory write
Memory write and invalidate
Memory read line
Memory read multiple
I/O read
I/O write
Interrupt acknowledge
Special cycle
Dual address
pci_clk
frame#
ad
c/be#
irdy#
trdy#
devsel#
1234
Address
Byte Enables
Command
Data
Wait
(AD
turnaround)
Data
Transfer
Figure 10-10. Basic single-data-phase read opera-
pci_clk
frame#
ad
c/be#
irdy#
trdy#
devsel#
123
n
Address
Data
Byte Enables
Command
Wait
Data
Transfer
Figure 10-11. Basic single-data-phase write opera-