User Manual

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USERS MANUAL
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Document number Revision
4/198 17-LXE 108 566 Uen PA7
3.5 System connector IO functionality
Note 1: The application IO can be one of the following listed types:
•
I Logic input (no pull up or pull down resistors required).
•
IOC Logic open-collector input.
•
O Logic output (no pull up or pull down resistors required).
•
OOC Logic open-collector output.
•
I/O Logic I/O.
The pin direction in this table is referenced from the application’s point of view.
Group Pin No Name Application Requirements App I/O
HW flow control is by default enabled in the phone module.
27
TD (DTMS)
Logic output to phone module. The application shall set this
output high upon start-up.
O
30 RD (DFMS) Logic input from phone module.
I
28 RTS
Logic output to phone module. Pulled down by the phone
module (R > 20k). The application shall set this pin low when
ready to receive data.
O
25 CTS
Logic input from phone module. This signal is initially set
high, indicating that the phone module is not ready to receive
data. It is set low when the phone module is ready to receive
data.
I
26 DTR
Logic output to phone module. This signal is pulled up in the
phone module (R > 20k).
This signal should be set low by the application during a data
call. A low to high transition will terminate the data call.
This signal is asserted by the application when it wishes to
open a communications channel. The phone module then
prepares the modem to be connected to the telephone circuit,
and, once connected, maintains the connection. When DTR is
de-asserted, the phone module is switched to "on-hook" to
terminate the connection.
O
Data
23 VPPFLASH/DCD
DCD: Logic input from phone module. This signal is set
default high. It goes low indicating that a data call is
established, (CONNECT) received from remote modem. The
signal goes high when data connection is disconnected.
Sent from the phone module (DCE) to the application (DTE) to
indicate that it has received a basic carrier signal from a
(remote) DCE.
VPPFLASH: The application shall not apply a voltage to this
pin unless they intend to use it as VPPFLASH in which case it
becomes a power output.
I/O