8 differential direction control, Differential direction control – Avago Technologies LSI53C140 User Manual
Page 29
SCSI Signal Descriptions
2-11
Ver. 2.1
Copyright © 1998–2001 by LSI Logic Corporation. All rights reserved.
5.
This stage is a trailing edge signal filter. When the signal deasserts,
the filter does not permit any signal bounce. The output signal
deasserts at the first deasserted edge of the input signal.
6.
The last stage develops pull-up and pull-down signals with drive and
3-state control.
7.
A parallel function ensures that bus (transmission line) recovery
occurs for a specified time after the last signal deassertion on each
signal line.
2.2.7 Control/Data, Input/Output, Message, and Attention Controls
(SCD, SIO, SMSG, and SATN)
A_SCD, A_SIO, A_SMSG, A_SATN, B_SCD, B_SIO, B_SMSG, and
B_SATN are control signals that follow these processing steps:
1.
The input signal is blocked if it is being driven by the LSI53C140.
2.
The next stage is a leading edge filter. This ensures the output does
not switch for a specified time after the leading edge. The duration
of the input signal determines the duration of the output.
3.
The final stage develops pull-up and pull-down controls for the SCSI
I/O logic, including 3-state controls for the pull-up.
4.
A parallel function ensures that bus (transmission line) recovery is for
a specified time after the last signal deassertion on each signal line.
2.2.8 Differential Direction Control
A_SD[15:0], A_SDP[1:0], A_SBSY, A_SSEL, A_SCD, A_SIO, A_SMSG,
A_SREQ, A_SACK, A_SATN, A_SRST, B_SD[15:0], B_SDP[1:0],
B_SBSY, B_SSEL, B_SCD, B_SIO, B_SMSG, B_SREQ, B_SACK,
B_SATN, and B_SRST are all multimode signals. The HVD_MODE input
pins control the mode and the voltage is sensed at the DIFFSENS inputs.
When the system selects HVD signaling and the DIFFSENS line sees
the proper voltage input, all the minus signal leads become SE
inputs/outputs to HVD drivers/receivers. All plus signals become the HVD
driver/receiver direction control signals. The A and B Sides are
independently controlled.
describes the Direction Control signal
polarity.