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Chapter 2 – Mechanical Specifications
SocketModem Global MT5634SMI Developer’s Guide 13
The MT5634SMI-P (Parallel) SocketModem uses a 22-pin interface to provide an on-board DAA with tip and ring
connections, audio circuit for call-progress monitoring, and parallel interface.
Figure 2–3. Parallel SocketModem Pins
Pin Descriptions for a Parallel SocketModem Device
Pin #
Signal
Name
I/O Description
1 Tip I/O
Tip Signal from Telco
2 Ring I/O
Ring Signal from Telco
24 –RESET I
Modem Reset (with weak pull-up). The active low –RESET input resets the
SocketModem logic and returns the AT command set to the original factory default
values or to "stored values" in NVRAM.
The modem is ready to accept commands within 6.5 seconds of power-on or reset.
Reset must be asserted for a minimum of 300 ns.
26 DGND GND
Digital Ground
25, 31,
34
A0, A1,
A2
I
Host Bus Address Lines 0 and 2. During a host read or write operation, A0
through A2 select an internal 16C450 or 16C550-compatible register. The state of
the divisor latch access bit (DLAB) affects the selection of certain registers.
30 INT O
Host Bus Interrupt. INT output is set high when the receiver error flag, receiver
data available, transmitter holding register empty, or modem status interrupt have
an active high condition. INT is reset low upon the appropriate interrupt service or
master reset operation.
32 –WR I
Host Bus Write. –WR is an active low, write control input. When –DS is low, –WR
low allows the host to write data or control words into a selected modem register.
33 –RD I
Host Bus Read. –RD is an active low, read control input. When –DS is low, –RD
low allows the host to read status information or data from a selected modem
register.
40 –DS I
Host Bus Device Select. –DS input low enables the modem for read or write.
61 VCC PWR
+5V or 3.3V Supply (depends upon model).
63 AGND GND
Analog Ground. This is tied common with DGND on the SocketModem. To
minimize potential ground noise issues, connect audio circuit return to AGND.
64 SPKR O
Speaker Output. SPKR is a single ended-output. It is tied directly to the CODEC.