User's Guide

The Hardware View SB300 Series
Page 94 Proprietary and Confidential 2110059 Rev 1.0
10.5. Jumpers
There are five jumper blocks provided on the MIB. Two of these are for the SB220, which is not
covered in this document. The three blocks used with the SB300 Series modems are summarized
below and discussed in detail in following sections.
The main jumper block is located next to the modem power switch and has eight pairs of pins.
When the jumper is connected it has these functions.
• ST IN1 Activate the input signals (not currently implement
• ST IN2 on the modems).
• ST IN3
• ST IN4
• \SHDN Activate the \SHDN signal to the modem.
• HOSTSHDN Enable the \SHDN signal from the SB301/302 host connector.
• TP CTRL Enable test point TP3.
• MODEM DIS Disable the RS-232 serial connection from the modem.
There is also a 3-pin jumper block for power selection. A jumper MUST connect the centre
pin (2) to one of the outside pins (1 or 3) to enable power to the modem.
• 1 – 2 MIB power is used.
• 2 – 3 Host power (SB301/302 host connector) is used.
A 2-pin jumper block is available to enable or disable the built-in speaker. When the jumper is
connected, the speaker is enabled.
10.5.1. Main Jumper Block
The main jumper block (J24) has eight pairs of pins, all labelled. NOTE that a correcting label has
been applied to reverse the labels for \SHDN and HOSTSHDN.
The first four pairs are to activate the four input signals of the SB320 (not currently implemented
by the modem). Two pairs are for direct MIB activation of the Shutdown (\SHDN) signal to the
modems and to enable the SB302 host interface to trigger this signal. There is one pair of pins for
activating TP3 and the last pair is to disable the modem side of the RS-232 / HCMOS serial signal
conversion.
10.5.1.1. ST INx – Status Inputs
Placing a jumper on one of these pins will force the signal active. At this time none of the status
input signals are used by the SB320 or SB300.
10.5.1.2. \SHDN – Shutdown
This jumper forces the modem’s Shutdown (\SHDN) input active (low). Placing a jumper on this
pair of pins forces the signal on. This will work regardless of the jumper setting of the host
shutdown enable.
10.5.1.3. HOSTSHDN – Host Shutdown Enable
This jumper enables the Shutdown (\SHDN) signal from the SB301/302 host interface to be
passed to the modem. Without the jumper installed, the signal will not reach the modem. This
jumper does not activate the signal; only allow the signal from the host connector to be passed to
the modem.
If the SB301/302 host connector is not being used, this jumper should be left open (not
connected). This will prevent a floating signal from the host connector block from reaching the
modem.
This jumper in independent of the forced-shutdown jumper (\SHDN).