Texas Instruments TMS320TCI648x - Manual (Page 24)

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double-word 0
4
double-word n-1 acklD rsv prio tt ftype destID sourcelD address rsrv xamsbs double-word 1 ... double-word n-2 CRC
PHY LOG TRA LOG TRA PHY
5 3 2 2 8 8 29 1 2 64 64 (n-4)*64 64 64 16
16 n*64+32 16 4 2 10
LOG PHY
10
TRA
2 4 9 * 6 4 + 32
LOG TRA
16
PHY
16
double-word 0
5
a c k l D sourcelD rsv
3
prio
2
ftype tt
2 4
destID
8 1
rsrv address
8 29
xamsbs
2 64
double-word 8 double-word 1
64 5*64
...
64
double-word 9
64
CRC
16
LOG
(n-9)*64 16
PHY
double-word 10
64
double-word n-2 double-word 11
64 (n-13)*64
... double-word n-1
64 64 16
CRC
n*64+96
n*64+80
PHY = Physical layer
TRA = Transport layer
LOG = Logical layer
2.1.2.3 Control Symbols
SC or PD parameter1 stype0 stype1 Parameter0 cmd CRC
5 3 3 5 5 3
Delimiter 1st Byte 2nd Byte 3rd Byte
8
SRIO Functional Description
Figure 6. 1x/4x RapidIO Packet Data Stream (Streaming-Write Class)
Note: Figure 6 assumes that addresses are 32-bit and device IDs are 8-bit.
The device ID, being an 8-bit field, will address up to 256 nodes in the system. If 16-bit addresses were
used, the system could accommodate up to 64k nodes.
The data stream includes a Cyclic Redundancy Code (CRC) field to ensure the data was correctly
received. The CRC value protects the entire packet except the ackID and one bit of the reserved PHY
field. The peripheral checks the CRC automatically in hardware. If the CRC is correct, a Packet-Accepted
control symbol is sent by the receiving device. If the CRC is incorrect, a Packet-Not-Accepted control
symbol is sent so that transmission may be retried.
Control symbols are physical layer message elements used to manage link maintenance, packet
delimiting, packet acknowledgment, error reporting, and error recovery. All transmitted data packets are
delimited by start-of-packet and end-of-packet delimiters. SRIO control symbols are 24 bits long and are
protected by their own CRC (see
Figure 7 ). Control symbols provide two functions: stype0 symbols
convey the status of the port transmitting the symbol, and stype1 symbols are requests to the receiving
port or transmission delimiters. They have the following format, which is detailed in Section 3 of the
RapidIO Physical Layer 1x/4x LP-Serial Specification.
Figure 7. Serial RapidIO Control Symbol Format
Control symbols are delimited by special characters at the beginning of the symbol. If the control symbol
contains a packet delimiter(start-of-packet, end-of-packet, etc.), the special character PD (K28.3) is used.
If the control symbol does not contain a packet delimiter, the special character SC (K28.0) is used. This
use of special characters provides an early warning of the contents of the control symbol. The CRC does
not protect the special characters, but an illegal or invalid character is recognized and flagged as
Packet-Not-Accepted. Since control symbols are known length, they do not need end delimiters.
24 Serial RapidIO (SRIO) SPRUE13A – September 2006
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