Texas Instruments TMS320TCI648x manual 4x RapidIO Packet Data Stream Streaming-Write Class

www.ti.com

SRIO Functional Description

Figure 6. 1x/4x RapidIO Packet Data Stream (Streaming-Write Class)

n*64+80

PHY		TRA		LOG		TRA	LOG	PHY
10	2		4		16		n*64+32	16

acklD	rsv	prio	tt	ftype	destID	sourcelD	address	rsrv	xamsbs	double-word￿0	double-word￿1	...	double-word￿n-2	double-word￿n-1	CRC
5	3	2	2	4	8	8	29	1	2	64	64	(n-4)*64	64	64	16
													n*64+96

PHY =￿Physical￿layer TRA = Transport￿layer LOG￿=￿Logical￿layer

	PHY	TRA		LOG	TRA	LOG	PHY	LOG	PHY
10		2	4		16	9 * 6 4 + 32	16	(n-9)*64	16

a c k l D rsv prio tt ftype destID sourcelD address rsrv xamsbs double-word￿0 double-word￿1 ...

double-word￿8

double-word￿9 CRC double-word￿10

double-word￿11

... double-word￿n-2 double-word￿n-1 CRC

5 3 2 2 4 8 8 29 1 2 64 64 5*64 64 64 16 64 64 (n-13)*64 64 64 16

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.

2.1.2.3Control Symbols

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

Delimiter	1st￿Byte		2nd￿Byte			3rd￿Byte
SC￿or￿PD	stype0	Parameter0	parameter1	stype1	cmd		CRC
8	3	5	5	3	3	5

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

Submit Documentation Feedback