EES3 Hardware Interface Description
3.16 Control Signals
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EES3_HD_v01.100b
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2009-08-12
Confidential / Released
3.16.3
Behavior of the RING0 Line (ASC0 Interface only)
The RING0 line is available on the first serial interface ASC0 (see also
nal 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 de-
signed to receive an interrupt when a falling edge on RING0 occurs. This solution is most ef-
fective, 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 hands-
free device, the RING0 line switches to ground in order to generate acoustic signals that
indicate the waiting call.
Figure 36:
Incoming voice/fax/data call
•
All other types of Unsolicited Result Codes (URCs) also cause the RING0 line to go low,
however for 1 second only.
Figure 37:
URC transmission
3.16.4
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.
