cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 302

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

12.0 ATM UTOPIA Interface
12.5 UTOPIA Level 1 Mode Cell Handshake Timing
Figure 12-2. Receive Timing in UTOPIA Level 1 Mode with Cell Handshake
12-12
RXD/RXPAR
NOTE(S):
(1)
(2)
(3)
RXCLAV
RxSOC
Once a cell transfer is started, RxClav is not sampled until the end of the cell.
RxEN* goes active only if there is room in the FIFO buffer for a complete cell.
RxEN* goes inactive at cell boundaries if the receive FIFO buffer cannot accept another cell.
RXCLK
RXEN*
(2)
H1
12.5 UTOPIA Level 1 Mode Cell Handshake
Timing
If high, the UTOPIA_MODE bit in the CONFIG0 register selects cell-level
handshaking. Received data is latched from the RxDATA[15:0] and RxPar lines on
the rising edge of RxClk after RxEN* is sampled active (see
parity computed over the RxData[15:0] lines is compared to the RxPar input. If in
error, the FR_PAR_ERR bit is set in the HOST_ISTAT0/ LP_ISTAT0 registers.
Data is discarded upon a parity error if the RSM_PHALT bit in the RSM_CTRL
register is set to a logic high, and the reassembly coprocessor halts. The RxSOC
signals to the CN8236 the start of cell. The RxClav input is the physical layer FIFO
buffer empty signal. When it is active, a complete cell is not present in the physical
receive FIFO buffer. The physical layer device sets RxClav inactive when it has a
complete cell to transfer. The CN8236 sets RxEN* to a logic low if it can accept a
complete cell. On the clock cycle after the last octet of a cell is transferred, the
CN8236 samples the RxClav input. If low, the physical device does not have a cell
to transfer. If RxClav is high, the physical device has another cell to transfer and the
CN8236 immediately starts receiving the next cell if it can accept a complete cell.
The FR_RMODE bit in the CONFIG0 register should be set to a logic low in this
mode.
H2
Mindspeed Technologies
***
(1)
P47
P48
ATM ServiceSAR Plus with xBR Traffic Management
X
™
H1
***
P47
Figure
(3)
28236-DSH-001-B
P48
12-2). The odd
CN8236
8236_071