DS3181/DS3182/DS3183/DS3184
77
Figure 8-27. UTOPIA Level 2 Transmit Multiple Cell Transfer Polled Mode
TADR
1
TPXA
TEN
TDATA
TSOX
19
20
…
TCLK
H3
P43 P44 P45 P46 P47 P48
P42
H1 H2
1F
N
1F
O
1F
L
1F M
1F N
1F O
1F P
1F
L
N
M
N
O
P
L
M
N
O
P
M
…
Transfer
Cell To:
N
H2 H3
H4
O
H1
23
4
5
7
6
8
10
11
12
13
14
15
16
17
18
9
Figure 8-28 shows a multidevice receive-interface multiple cell transfer from different PHY devices. On clock edge
2, the ATM device polls PHY device 'N'. On clock edge 3, PHY device 'N' indicates to the ATM device that it has a
complete cell ready for transfer by asserting RPXA. On clock edge 4, the ATM device selects PHY device 'N'. On
clock edge 5, the ATM device asserts
REN. On clock edge 6, PHY device 'N' starts a cell transfer by placing the
first byte of cell data on RDATA, and asserting RSOX to indicate the transfer of the first byte of the cell. On clock
edge 7, PHY device 'N' deasserts RSOX as it continues to place additional bytes of the cell on RDATA. On clock
edge 12, the ATM device polls PHY device 'O'. On clock edge 13, PHY device 'O' indicates to the ATM device that
it has a complete cell ready for transfer by asserting RPXA. On clock edge 16, the ATM device deselects PHY
device 'N' and selects PHY device 'O' by deasserting
REN and placing PHY device 'O's address on RADR. On
clock edge 17, the ATM device asserts
REN and PHY device 'N' stops transferring cell data and tri-states its
RDATA and RSOX outputs. On clock edge 18, PHY device 'O' starts a cell transfer by placing the first byte of cell
data on RDATA, and asserting RSOX to indicate the transfer of the first byte of the cell. On clock edge 19, PHY
device 'O' deasserts RSOX as it continues to place additional bytes of the cell on RDATA.
Figure 8-28. UTOPIA Level 2 Receive Multiple Cell Transfer Polled Mode
RADR
1
RPXA
REN
RDATA
RSOX
19 20
…
RCLK
1F
N
1F
O
1F
M
1F
O
1F
P
1F
O
1F
N
1F
P
N
M
N
O
L
M
O
P
O
N
M
…
H1
H2
Transfer
Cell From:
N
H3
O
H2
H1
P43 P44 P45 P46 P47 P48
P42
P41
2
345
7
6
8
10 11 12 13 14 15 16 17 18
9
Figure 8-29 shows a multidevice receive-interface unexpected multiple cell transfer. Prior to clock edge 1, the cell
transfer was started. On clock edge 4, since no other PHY device has a cell ready for transfer, the ATM device
assumes another cell transfer from PHY device 'N' and leaves
REN asserted. On clock edge 5, PHY device 'N'
stops transferring cell data and indicates that it does not have another cell ready for transfer by not asserting
RSOX. On clock edge 6, the ATM device deasserts
REN to end the cell transfer process. At the same time, PHY
device 'N' indicates to the ATM device that it now has a complete cell ready for transfer by placing the first byte of
cell data on RDAT, and asserting RSOX to indicate the transfer of the first byte of the cell. On clock edge 7, PHY
device 'N' tri-states its RDAT and RSOX outputs because
REN is deasserted. On clock edge 8, the ATM device
selects PHY device 'N'. On clock edge 9, the ATM device asserts
REN. On clock edge 10, PHY device 'N'
continues the cell transfer by placing the second byte of cell data on RDAT, and deasserting RSOX.