User's Manual
Table Of Contents
- Contents
- Figures
- Tables
- Document history
- Introduction
- Product concept
- GSM application interface
- GSM/GPRS operating modes
- Power supply
- Power up / down scenarios
- Automatic GPRS Multislot Class change
- Charging control of the GSM part
- Power saving
- Summary of state transitions (except SLEEP mode)
- RTC backup for GSM part of XT55/56
- Serial interfaces of the XT55/56 GSM part
- Audio interfaces
- SIM interface
- Control signals
- GPS application interface
- GSM and GPS antenna interfaces
- Electrical, reliability and radio characteristics
- Mechanics
- Reference approval
- Example applications
- List of parts and accessories
XT55/56 Hardware Interface Description
Confidential / Released
s
XT55/56_hd_v02.06a Page 66 of 125 17.12.2004
3.12.2.2 Using the GSM_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].
When controlled from the SYNC pin the LED can display the functions listed in Table 18.
Except for the LED state "off", all LED patterns apply no matter whether XT55/56 works at full
functionality level AT+CFUN=1 or has entered a "temporary wake-up state" during one of the
CYCLIC SLEEP modes. See Chapter 3.6 for details on the various SLEEP modes.
Table 18: Coding of the status LED
LED mode Operating status of XT55/56
Permanently off XT55/56 is in one of the following modes: POWER DOWN mode,
ALARM mode, CHARGE-ONLY mode, SLEEP mode with no 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.
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 22)