
IBM3206K0424
IBM Processor for Network Resources
Preliminary
ATM PHY Bus Interface
Page 52 of 676
pnr25.chapt02.01
August 14, 2000
:
PHY Bus Pin Descriptions 
 (Page 1 of 3)
Quantity
Pin Name
Input/Output
Pin Function
Pin Description
16
 FYTDAT (15 - 0)
Output
 PHY Transmit Data
When using an external PHY, this 16-pin bus carries the ATM 
CELL octets that are loaded in the PHY Transmit FIFO. When 
using the internal framer, bits 15, 14, and 13 are used for the 
RX HDLC interface signals OFPrxR1Data, OFPrxR1DS, and 
OFPrxRclk, respectively.
2
 FYTPAR (1 - 0)
 Output
 Transmit Data Parity
When using an external PHY, these are byte parity signals for 
FYTDAT. When using the internal framer, bit 1 provides the RX 
Out-Of-Frame indication, OOF, and bit 0 provides the optical/
electrical module transmit shutdown control signal, OFPtxS-
Down. When using a POS-PHY, bit zero provides the TERR 
signal.
1
 FYTSOC
 Output
 Transmit start of Cell
When using an external PHY, this indicates the start of cell on 
FYTDAT. When using the internal framer, this provides the TX 
HDLC interface signal, OFPtxT1Dclk. When using a POS-PHY, 
this indicates TSOP.
1
 FYTWRB
 Output
 Transmit write strobe
When using an external PHY, this signal is used to write ATM 
cells to the transmit FIFO. When using the internal framer, this 
signal provides the 19.44MHz TX clock, RefClkT. When using 
a Utopia Cell or POS-PHY interface, this signal provides the 
write clock based on the clock received on the TXCLK pin.
1
FY
n
TENB
 Output
 Transmit write enable
When using an external PHY, this indicates that transmit data 
to the PHY is valid. When using the internal framer, this pro-
vides the TX HDLC interface signal, OFPtxT1DS. 
1
FY
n
RENB
Output
 Receive write enable
When using an external PHY, this indicates to the PHY that the 
IBM3206K0424 is ready to accept data. When using the inter-
nal framer, this provides the clock recovery reset signal, 
RSTCRec1.
1
FYRRDB
 Output
 Receive ready strobe
When using an external PHY, this is used to read ATM cells 
from the PHY receive FIFO. When using the internal framer, 
this signal provides the 19.44MHz RX clock, RxByClk. When 
using a Utopia Cell or POS-PHY interface, this signal provides 
the write clock based on the clock received on the RXCLK pin.
16
 FYRDAT(15 - 0)
Input
 PHY Receive Data
When using an external PHY, this 16-pin bus carries the ATM 
CELL octets that are read from the PHY Receive FIFO. 
2
 FYRPAR(1 - 0)
 Input
 PHY Receive Data Parity
When using an external PHY, these are byte parity signals for 
FYRDAT. When using the internal framer, bit 1 provides the 
optical/electrical module low power indication signal, OFPtx-
LPow, and bit 0 is not used. When using a POS-PHY, bit 0 
should be connected to RERR.
Note:  
Because some of the PHY transmit I/Os are used for receive framer functions and vice versa, there are some restrictions on how 
the interfaces can be used.
1. If the transmit path is using an external PHY and the receive path is using the internal framer, FYTPAR(1) will assume the OOF 
function and not be available as a parity output. This is only a concern if the PHY uses a 16-bit data interface and parity is being 
used.
2. If the receive path is using an external PHY and the transmit path is using the internal framer, FYRPAR(1) will assume the OFPtx-
LPow function and not be available as a parity input. This is only a concern if the PHY uses a 16-bit data interface.
3. If the transmit path is using an external PHY and the receive path is using the internal framer, and the external PHY has a 16-bit 
data interface, then the receive HDLC interface cannot be used. The three I/O for the RX HDLC interface will instead take on the 
function of FYTDAT(15-13).