User's Manual

Confidential
USERS MANUAL
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Document number Revision
1/198 17-5/FCP 101 3317 Uen A
A falling edge indicates an alert or message. The signal remains low for a period of time
before going high. An SMS-page or unsolicited response/result code generates one pulse
(the length is configurable using an AT command)[TBC].
The ring indicator is implemented on the daughter card as an open collector transistor
output to allow the host the convenience of driving the host equipment circuitry.
5.2.4 LED
Function: LED
Description: LED-signal indicating a status change
Pin Number: 22
Signal Name: LED [modem
⇒host]
If not used: Leave open
Details:
The LED is implemented on the Daughter Card as an open collector transistor output
which providesa driver level interface to an LED acting as a status indicator for the user.
The LED output can be made to blink at a rate pre-determined by modem software.
5.2.5 VREF
The function of VREF is already described in 5.1.3. This interface can be used as a
status indicator to the host that the modem is still powered. VREF is present whilst the
modem is powered and is removed upon the completion of the modem power down. This
feature can be useful in the event of a communications lock-up between the host and the
daughter card.