Behavior Of The Ring0 Line (Asc0 Interface Only); Pwr_Ind Signal; Figure 36: Incoming Voice/Fax/Data Call; Figure 37: Urc Transmission - Siemens AC75 Hardware Interface Description

AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.17.3

Behavior of the RING0 Line (ASC0 Interface only)

The RING0 line is available on the first serial interface ASC0 (see also Chapter 3.10). The
signal serves to indicate incoming calls and other types of URCs (Unsolicited Result Code).
Although not mandatory for use in a host application, it is strongly suggested that you
connect the RING0 line to an interrupt line of your application. In this case, the application
can be designed to receive an interrupt when a falling edge on RING0 occurs. This solution
is most effective, particularly, for waking up an application from power saving. Note that if the
RING0 line is not wired, the application would be required to permanently poll the data and
status lines of the serial interface at the expense of a higher current consumption. Therefore,
utilizing the RING0 line provides an option to significantly reduce the overall current
consumption of your application.
The behavior of the RING0 line varies with the type of event:
•
When a voice/fax/data call comes in the RING0 line goes low for 1s and high for another
4s. Every 5 seconds the ring string is generated and sent over the /RXD0 line.
If there is a call in progress and call waiting is activated for a connected handset or
handsfree device, the RING0 line switches to ground in order to generate acoustic
signals that indicate the waiting call.
RING0
1s
Ring
string
•
All other types of Unsolicited Result Codes (URCs) also
cause the RING0 line to go low, however for 1 second
only.
3.17.4

PWR_IND Signal

PWR_IND notifies the on/off state of the module. High state of PWR_IND indicates that the
module is switched off. The state of PWR_IND immediately changes to low when IGT is
pulled low. For state detection an external pull-up resistor is required.
AC75_HD_V00.202
4s
1s
Ring
string

Figure 36: Incoming voice/fax/data call

Figure 37: URC transmission

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s
4s
1s
Ring
string
RING0
1s
URC
27.04.2006