XRS10L240 Datasheet, PDF (14/38 Pages) Exar Corporation – SERIAL ATA II: PORT MULTIPLIER / PORT SELECTOR

EXSTOR - 1 XRS10L240
SERIAL ATA II: PORT MULTIPLIER / PORT SELECTOR
REV. 1.05
3.5.2 Transmission from a device to a host
A device indicates a transmit to a host in the same way as would be done if the host and device were attached
directly. This transaction obeys the following procedure:
1. After receiving an X_RDY primitive from the device, the XRS10L240 will determine if the X bit is set in the
device port's PSCR[1] (SError) register. The XRS10L240 will not issue an R_RDY primitive to the device
until this bit is cleared to zero.
2. The XRS10L240 will then receive the frame from the device. The XRS10L240 will fill in the PM Port field
with the port address of the transmitting device. The XRS10L240 will then check the CRC received from
the device, and if valid, it will recalculate the CRC based upon the new PM Port field. If the CRC calculated
from the device is incorrect, the XRS10L240 will corrupt the CRC sent to the host to ensure propagation of
the error condition
3. The XRS10L240 will issue an X_RDY primitive to the host to start the transmission of the frame to the host.
After the host issues an R_RDY primitive to the XRS10L240, the frame from the device, with the updated
CRC, will then be transmitted to the host. The XRS10L240 will not send an R_OK status primitive to the
device until the host has issued an R_OK primitive to indicate successful frame reception. In this way, the
R_OK status handshake will be interlocked from the device to the host.
If an error is detected during any part of the frame transfer, the XRS10L240 will ensure that the error condition
is propagated to the host and the device.
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