DS34S132GNA2+ Maxim Integrated, DS34S132GNA2+ Datasheet - Page 67

• Manufacturer Part Number: DS34S132GNA2+
• Description: Communication ICs - Various 32Port TDM-Over-Pack Transport Device
• Manufacturer: Maxim Integrated

Specifications of DS34S132GNA2+

• Rohs: yes
• Part # Aliases: 90-34S13+2N2

When TXOTSE is enabled, TXOTSO identifies the OAM Timestamp Dword position in the packet. The CPU must
make the initial OAM Timestamp value 0x0000 in the packet stored in the TXP CPU FIFO. The S132 overwrites
that position with the current OAM Timestamp value as the packet is being transmitted at the Ethernet Port.
The S132 uses the
can be programmed for 1 us or 100 us using G.GCR.OTRS.
The OAM Timestamp can only be positioned on Dword boundaries within the Application Header. Because
Ethernet Headers do not commonly include an integer number of Dwords, the Application Header is commonly
offset by 2 bytes in the Ethernet packet, as depicted in
bytes depicted in this figure). If the OAM Timestamp position is referenced instead to the beginning of the Ethernet
packet, some example OAM Timestamp byte positions are 46, 50, 54 (etc.), which would equate to TXOTSO
Dword = 11, 12 , 13 (etc.; respectively).
When a TXP CPU Packet uses the IPv4 protocol, the S132 can be programmed to assist with the generation of the
IPv4 Header FCS. The CPU must pre-calculate and include an IP FCS for all of the fields of the IP Header but the
IP Total Length field. The S132 modifies the IP FCS on-the-fly to include the IP Total Length. This allows the CPU
to store a “generic” pre-calculated IP FCS with each stored IP Header in CPU memory. The CPU pre-calculates the
IP FCS for the IP Header beginning with the IP Version field and ending with the IP Destination Address, but using
“0” values in the IP Total Length and IP Header FCS fields. The IPv6 Header does not include an FCS.
When a TXP CPU Packet uses the UDP/IP protocol, the S132 can be programmed to assist with the generation of
the FCS in the UDP Header. The CPU must include a UDP FCS for all but the IP length and UDP length fields. The
CPU pre-calculates the UDP FCS with a Pseudo IP Header that is added to the beginning of the UDP packet
(added only for this UDP FCS calculation) and including the entire UDP packet (from UDP Source Port to the end
of the UDP Payload; per RFC768), but calculates with “0” values in the “UDP Length” field of the Pseudo IP
Header, the ”Length” field of the UDP Header and the “Checksum” field of the UDP Header. The S132 modifies the
pre-calculated UDP FCS on-the-fly to include the lengths. This function can be used when the S132 is programmed
to add a TXP OAM Timestamp.
If the S132 FCS functions are not needed, then the CPU should not identify the packet as IPv4 or UDP (so that the
S132 does not modify the FCS values) and the CPU must include the IP and UDP FCS values for transmission.
All of these functions can be enabled at the same time or in various combinations as identified in
the CPU is ready the CPU writes the entire TXP CPU Packet including the pre-calculated FCS values, the “real”
packet length values and TXP OAM Timestamp = “0” (when applicable). For example, when TXOTSO = 1, TXUDP
= 1 and TXIPV4 = 1 (Add TXP OAM Timestamp & Re-calculate UDP FCS & IPv4 FCS), the CPU provides the
entire CPU packet (from Ethernet DA to the end of the Ethernet Payload) including the IP Total Length field (to
indicate the size of the IP packet), the pre-calculated IP FCS, the UDP Length field (to indicate the size of the UDP
packet), the pre-calculated UDP FCS and the “0” value in the TXP OAM Timestamp position. The S132 then
overwrites with the TXP OAM Timestamp and corrects the IP FCS and UDP FCS values.
Table 9-16. Modify FCS and Add TXP OAM Timestamp Functions
Application
Re-calculate IPv4 FCS to include Length
For IPv4: Re-calculate UDP FCS & IPv4 FCS to include Length
For IPv6 packets: Re-calculate UDP FCS to include Length
Add TXP OAM Timestamp to any protocol (with no FCS modifications)
For IPv4: Add TXP OAM Timestamp & Re-calculate UDP FCS & IPv4 FCS
For IPv6: Add TXP OAM Timestamp & Re-calculate UDP FCS
The Write TXP CPU Packet process can be polling based using the
using the
the CPU is ready to Write a TXP CPU Packet into the TXP CPU FIFO, the CPU should begin by verifying that the
TXP CPU FIFO is empty (read the FIFO status at
3). The CPU then Writes the Dwords for the packet at EMA.WDR.EMWD. Each successive Write at
EMA.WDR.EMWD
CPU FIFO the CPU must indicate the length of the packet (EMA.WCR.TL), how many packet bytes are included in
the last Dword (EMA.WCR.TLBE) and indicate that the packet should be transferred to the TXP CPU Queue in the
SDRAM
EMA.WSR1.WFES
19-4750; Rev 1; 07/11
(EMA.WCR.TPCWC
EMA.WSRL1.WFESL
fills the next Dword position in the FIFO. When the entire packet has been stored in the TXP
will indicate that the FIFO is empty.
ETHCLK
signal to generate the TXP OAM Timestamps. The TXP OAM Timestamp Resolution
= 6). When the complete packet has been transferred to the TXP CPU Queue,
(latched status) and
EMA.WSR1.WFES
EMA.WSRIE1.WFEIE
Figure 9-25
EMA.WSR1.WFES
(Ethernet packets do not include the “dummy”
or flush the FIFO with
TXOTSE
(Interrupt enable) register bits. When
0
0
0
1
1
1
status bit or interrupt driven
DS34S132 DATA SHEET
TXUDP
0
1
1
0
1
1
EMA.WCR.TPCWC
Table
TXIPV6
0
0
1
0
0
1
9-16. When
67 of 194
TXIPV4
1
1
0
0
1
0
=