User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
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MC55/56_hd_v03.00 Page 63 of 104 16.08.2005
3.12.2.2 Using the SYNC pin to control a status LED
As an alternative to generating the synchronization signal, the SYNC pin can be used to
control a status LED on your application platform.
Especially in the development and test phase of an application, system integrators are
advised to use the LED mode of the SYNC pin in order to evaluate their product design and
identify the source of errors.
To avail of this feature you need to set the SYNC pin to mode 1 by using the AT^SSYNC
command. For details see [1].
Table 18: Coding of the status LED
LED mode Operating status of MC55/56
Permanently off MC55/56 is in one of the following modes:
• POWER DOWN mode
• ALARM mode
• CHARGE-ONLY mode
• NON-CYCLIC SLEEP mode
• CYCLIC SLEEP mode with no temporary wake-up event in
progress.
600 ms on / 600 ms off Limited Network Service: No SIM card inserted or no PIN entered, or
network search in progress, or ongoing user authentication, or network
login in progress.
75 ms on / 3 s off IDLE mode: The mobile is logged to the network (monitoring control
channels and user interactions). No call in progress.
75 ms on / 75 ms off /
75 ms on / 3 s off
One or more GPRS contexts activated.
0.5 s on / off depending on
transmission activity
Packet switched data transfer in progress. LED goes on within
1 second after data packets were exchanged. Flash duration is
approximately 0.5 s.
75 ms URC
Permanently on Depending on type of call:
Voice call: Connected to remote party.
CSD call: Connected to remote party or exchange of parameters while
setting up or disconnecting a call.
LED Off = SYNC pin low. LED On = SYNC pin high (if LED is connected as illustrated in Figure 23)
Note: When a temporary wake-up event (URC, call, packet switched transfer) occurs in
CYCLIC SLEEP mode the LED flashes. See Table 11 for details on the various
SLEEP modes and wake-up events.