User Manual

DM15/25 Integrator’s Manual 22 OF 38
The pin direction in this table is seen from the application’s point of view.
Group
Pin
No.
Name Application Requirements
App
I/O
1
HW flow control is by default enabled in the phone module.
23 TD (DTMS)
Logic output to phone module. The application shall set
this output active high upon startup.
O
26 RD (DFMS) Logic input from phone module. I
24 RTS
Logic output to phone module. Pulled down by the phone
module (R > 20k). The application shall set this pin active
low when ready to receive data.
O
21 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
Data
22 DTR
Logic output to phone module. This signal is pulled up in
the phone module (R > 20k).
This signal should be set high by the application during a
data call. A high to low transition will terminate the data
call.
This signal is asserted (logic high) 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 (logic low), the
phone module is switched to "on-hook" to terminate the
connection.
O
Data
19 VPPFLASH/DCD
DCD: Logic input from phone module. This signal is set
default high. It goes low indicating that a data or fax 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
15 PCMULD Logic output to phone module. O
16 PCMDLD Logic input from phone module. I
14 PCMSYNC Logic input from phone module. I
PCM
15 PCMCLK Logic input from phone module. I