Serial ATA [SATA] Bus Protocol Frame
External Serial ATA (Advanced Technology Attachment)
[eSATA Description] [Interface
ICs]
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External SATA [eSATA] brings the SATA Hard Drive bus outside the PC chassis and allows external devices to be mounted to a SATA connection. The data cable runs out to a maximum of 6 feet. A shielded cable length of 3 feet or 6 feet is common for eSATA. The eSATA cable is shielded, but otherwise the same cable as used with SATA inside the PC. The external eSATA connector does not have the 'L' shaped key like the internal connector. Internal SATA style connectors will not mate with external SATA style connectors. The Serial ATA bus [SATA] is the serial version of the IDE [ATA] spec. SATA uses a 4 conductor cable with two differential pairs [Tx/Rx], plus an additional three grounds pins and a separate power connector. Data runs at 150MBps [1.5GHz] using 8B/10B encoding and 250mV signal swings. Later SATA enhancements move the data transfer speed to; 300MBps [3.0Gbps], and then 600MBps [6.0Gbps]. The current speed for SATA is 300Mbps [3Gbps]. The newest revision is called xSATA and allows external connects to 8 meters.
SATA Protocol
The SATA Frame structure used between Host and Device is shown in the
graphic below. The frame is made up of multi Dwords, which are in turn
encapsulated by flow control and CRC information. The SATA frame begins
with a Start-of-frame [SOF]. The SOF is followed by the Frame Information
Structure [FIS]. Then the Cyclic Redundancy Code [CRC] is placed in the
frame. The final block in the message is an End-of-Frame [EOF]. SATA uses
a 32bit CRC [calculated over the contents
of a (FIS) Frame Information Structure], stored as the 'Dword'. The
32-bit CRC polynomial is X32+ X26+ X23+
X22+ X16+ X12+ X11+
X10+ X8+ X7+ X5+
X4+ X2+ X + 1.
SATA Electrical
Serial ATA uses LVDS [EIA/TIA-644]
with voltages of 250mV. Serial ATA is a point-to-point interface where
each device is directly connected to the host via a dedicated link.
Because Serial ATA uses a dedicated link, adding another drive to the
computer has no impact on bandwidth. The Bit Encoding used is: Non Return
to Zero (NRZ)
encoding for data communication on a differential two wire bus. The use
of NRZ encoding ensures compact messages with a minimum number of
transitions and high resilience to external disturbance. The termination resistor is 100 Ohms [+/- 5 Ohms]
differential.
SATA Physical
Serial ATA uses only 4 signal pins, improving pin efficiency over the
parallel ATA interface which uses 26 signal pins going between devices
[over an 80 conductor ribbon cable onto a 40 pin header connector].
Serial ATA also provides the opportunity for devices to be 'hot-plugged',
devices may be inserted or removed while the system is powered on. The
pin-out tables for Serial ATA are listed below.
The primary function of Serial ATA bus is to form an interface between
the Motherboard
and the Hard Disk Drive
[HDD]. The Hard Drive may have a SATA connector and a legacy PATA data connector, with a legacy
PATA power connector, so the
device may function in either a legacy [older] mother-board or a currently
produced mother-board. In this case the mother board S-ATA interface would
be developed from a peripheral add-on board and not the mother-board.
Power connectors on a HDD are header pins for a P-ATA interface and
card-edge finger blades in the case of S-ATA.
SATA and eSATA use LVDS [EIA/TIA-644] with voltages of 250mV.
Atmel {Serial ATA Bridge IC, PATA to SATA Converter}
Genesys logic {Serial ATA Gen II 3.0Gbps PHY IP Core}
LSI Corporation {8-Port 3Gbps SATA Controller}
Marvell {Serial ATA Bridge IC, PATA to SATA Converter}
Mixel {Quad Gigabit Transceiver IP}
PLX Technology {FireWire/USB to SATA Controllers, USB to SATA Controllers, Consumer Network Attached Storage (NAS) SoC, Consumer Direct Attached Storage (DAS) SoC}
Silicon Storage Technology, Inc. 'SST' {SATA Disk Controller IC}
Soft Mixed Signal Corporation 'SMS' {SATA PHY transceiver IP}
Another listing of PC Chip Set Manufacturers {This Site}
Serial ATA: High Speed Serialized AT Attachment; Revision 1.0,
1/2003
Serial ATA: High Speed Serialized AT Attachment; Revision 1a,
8/2001
Serial ATA II: Electrical Specification; Revision 1.0, 5/2004
SATA PHY Interface Specification [SAPIS] Intel
T13 {Technical Committee T13; AT Attachment} ...... Serial ATA {Serial ATA Working Group}
The Serial ATA bus is defined over two separate connectors, one for the
data lines and one for the power lines. A Serial ATA Hard drive may also
have a third connector for legacy PATA power
connections. The PATA power connector may be used in instead of the SATA
power to supply a connection which is more rugged and reliable then the
SATA-1 power connection.
The pinout for SATA is listed on the SATA Pinout
page
The cable uses two shielded pairs to carry data. The wire is 26 AWG solid copper wire. The impedance is 100 ohms. Common internal SATA cable lengths are 12, 18, and 36 inches. The internal cables maybe straight both ends or 90 degree. Shielded external SATA [eSATA] data cable run 3 feet or 6 feet. A Cable may also contain both SATA Data and Power combined into an 18 inch cable. Illuminated cable is also available. For reference; the older IDE flat cable is five times wider then the new Serial ATA round cable. The smaller Serial ATA cable allows for better air flow within the Personal Computer chassis
3Ware "AMCC" {39 inch Serial ATA Cable}
Amphenol {SATA Connector Manufacturer}
BAFO Technologies {SATA - 7 Pin Internal, eSATA 7 Pin External with Metal Shield, 15 Pin - 4 Pin Housing Power}
Belkin Corporation {Serial ATA Cable 18 inches, 24 inches, 3 foot length, Right Angled, Multi-Colored}
Circuit Assembly {Serial ATA Signal Cable}
DATACOMM Cables Inc {SATA 150, Straight 19"and 39 inch long. 90 degree bend 18" and 36 inch long}
Delphi {Serial ATA Cables}
Hitachi Cable Manchester, Inc. {Serial ATA 4-Conductor PVC Cable, 100 ohm differential Impedance}
Molex {Serial ATA Connectors and Cables Assemblies}
TaiSol Electronics {Serial ATA DIP Connectors, Serial ATA 15P/7P Male Female Connectors and Serial ATA Data Cable, Serial ATA Power Cable}
Tripp Lite {Serial ATA Signal Cable - 39" 7 Pin Straight Female/Female}
Tyco Electronics {Serial ATA 7 Position PCB MT Components, 7 Position Type I/type II Cable Assemblies, 26 AWG Bulk Cables}
Electronic Engineering Design Key words: Personal Computer Interface, Serial ATA, SATA, eSATA, External SATA, PC, Hard drive bus, IC, IDE Physical Interface, Description, Pin Out, Pinout, Parallel ATA, PATA, LVDS, Enterprise, Direct Attached Storage, DAS, Networked Attached Storage, NAS, Storage Area Network, SAN, Peripheral Interface, Advanced Technology Attachment, Direct Access Storage Devices, DASD, Implementation, Hard Disk Drive, HDD, Host Bus Adapters, HBA, Native Command Queuing, NCQ.
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