User's Manual
Part 1 − Universal Socket Connectivity Chapter 1 – Universal Socket Connectivity
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342K) 12
Pin Signal
Name
In/Out Description
24 –RESET*
I
Device Reset (with pull-up). The active low –RESET input resets the device logic
and returns the configuration of the device to the original factory default values or
"stored values" in the NVRAM. –RESET is tied to VCC through a time-constant
circuit for “Power-on-Reset” functionality. The SocketModem is ready to accept
commands after a fixed amount of time (“X” Time) after power-on or reset.
Model Time Constant "X" Time Minimum Reset Pulse*
MTSMC-G2 250 ms 6 seconds 100us
MTSMC-C 250 ms 3-15 seconds 500us
MTSMC-E1 250 ms 3-15 seconds 500us
MTSMC-H 250 ms 10 seconds 100us
MT9234SMI 400 ms 6 seconds 100us
MT5692SMI 250 ms 6 seconds 100us
MT2492SMI 250 ms 6 seconds 100us
MT100SEM-IP 250 ms 6 seconds 100us
MT810SWM-IP 250 ms 6 seconds 100us
MTS2BTSMI 250 ms 6 seconds 100us
*The SocketModem device may respond to a shorter reset pulse.
Reset Line Interface for the MT5692SMI. The modem’s reset line employs a 10K
pull up resistor. If an open collector driver is to be used, run that output to the
modem only and use a separate driver for other embedded components. The
modem’s reset signal may also be driven by a circuit that both sinks and sources
current if desired. It is also important to note that these modems do not require an
external reset. They have their own internal reset circuitry and voltage monitor and
will function correctly even if the reset input is open.
Reset GPRS and CDMA (MTSMC-G2 and MTSMC-C). This signal is used to force
a reset procedure by providing low level during reset of at least 500us. The signal is
considered an emergency reset only. A reset procedure is already driven by internal
hardware during the power-up sequence. If no external reset is necessary, this input
can be left open. If used (emergency reset), it has to be driven by an open collector
or an open drain.
Reset EDGE with pull-up (MTSMC-E1). The active low –RESET input resets the
device logic and returns the configuration of the device to the original factory default
values of "stored values" in the NVRAM. The SocketModem is ready to accept
commands after a fixed amount of time after power-on or reset.
25
USB_VBUS I
USB Voltage Sense. Senses the voltage level of the USB to determine if the bus is
available.
26
GND GND
Logic Ground.
27
USB_DP I/O
USB Data Positive. Positive pin of the USB data pair.
28
USB_DN I/O
USB Data Negative. Negative pin of the USB data pair.
29
LED DCD O
DCD (Active High). Output from 74LCX14 with a 1000 Ohms resistor in series.
SocketWireless Bluetooth (MTS2BTSMI): When lit, indicates a connection. No
series resistor.
30
LED RX O
RX (Active High). Output from 74LCX14 with a 1000 Ohms resistor in series.
SocketWireless Bluetooth (MTS2BTSMI): No series resistor.
31
LED DTR O
DTR (Active High). Output from 74LCX14 with a 1000 Ohms resistor in series.
SocketWireless Bluetooth (MTS2BTSMI): No series resistor.
32
LED TX O
TX (Active High). Output from 74LCX14 with a 1000 Ohms resistor in series.
SocketWireless Bluetooth (MTS2BTSMI): No series resistor.
33
–RTS I
Request to Send (Active Low). –RTS is controlled by the DTE to indicated
whether or not the DTE is ready to receive data. –RTS ON (low) indicates that the
DTE is ready to receive data from the modem on RXD. –RTS OFF indicates to the
SocketModem that it should not transfer data on the RXD.
In the command state, the modem ignores –RTS.
Note: When the –RTS pin is not in use, it should be tied low.
* RESET – A Design Consideration: Allowing the host processor to control the RESET line of the SocketModem provides the
benefit of allowing the host to reset the device in the event of a failure to respond normally. Resetting the SocketModem will
return it to a known functional state.