Hardware Interface Description - KORE Telematics
Hardware Interface Description - KORE Telematics
Hardware Interface Description - KORE Telematics
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XT55/56 <strong>Hardware</strong> <strong>Interface</strong> <strong>Description</strong><br />
Confidential / Released<br />
s<br />
3.12.3 Behavior of the GSM_RING0 line (ASC0 interface only)<br />
The GSM_RING0 line is available on the first serial interface (ASC0). The signal serves to<br />
indicate incoming calls and other types of URCs (Unsolicited Result Code).<br />
Although not mandatory for use in a host application, it is strongly suggested that you<br />
connect the GSM_RING0 line to an interrupt line of your application. In this case, the<br />
application can be designed to receive an interrupt when a falling edge on GSM_RING0<br />
occurs. This solution is most effective, particularly, for waking up an application from power<br />
saving. Note that if the GSM_RING0 line is not wired, the application would be required to<br />
permanently poll the data and status lines of the serial interface at the expense of a higher<br />
current consumption. Therefore, utilizing the GSM_RING0 line provides an option to<br />
significantly reduce the overall current consumption of your application.<br />
The behavior of the GSM_RING0 line varies with the type of event:<br />
• When a voice call comes in the GSM_RING0 line goes low for 1s and high for another<br />
4s. Every 5 seconds the ring string is generated and sent over the GSM_RXD0 line.<br />
If there is a call in progress and call waiting is activated for a connected handset or<br />
handsfree device, the GSM_RING0 line switches to ground in order to generate acoustic<br />
signals that indicate the waiting call.<br />
GSM_RING0<br />
4s<br />
4s<br />
1s 1s 1s<br />
Ring<br />
Ring<br />
Ring<br />
string<br />
string<br />
string<br />
Figure 23: Incoming voice call<br />
• Likewise, when a Fax or data call is received, GSM_RING0 goes low. However, in<br />
contrast to voice calls, the line remains low. Every 5 seconds the ring string is generated<br />
and sent over the GSM_RXD0 line.<br />
GSM_RING0<br />
5s<br />
5s<br />
Ring<br />
string<br />
Ring<br />
string<br />
Ring<br />
string<br />
Figure 24: Incoming data call<br />
• All types of Unsolicited Result Codes (URCs) also cause the<br />
GSM_RING0 line to go low, however for 1 second only.<br />
For example, XT55/56 may be configured to output a URC<br />
upon the receipt of an SMS. As a result, if this URC type<br />
was activated with AT+CNMI=1,1, each incoming SMS<br />
causes the GSM_RING0 line to go low. See [1] for detailed<br />
information on URCs.<br />
GSM_RING0<br />
1s<br />
URC<br />
Figure 25: URC transmission<br />
XT55/56_hd_v02.06a Page 68 of 125 17.12.2004
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