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 31 of 125 17.12.2004
3.3.1.1 Turn on the GSM part of XT55/56 using the ignition line GSM_IGT
(Power on)
To switch on the XT55/56 GSM part the GSM_IGT (Ignition) signal needs to be driven to
ground level for at least 100ms and not earlier than 10ms after the last falling edge of
GSM_VDD. This can be accomplished using an open drain/collector driver in order to avoid
current flowing into this pin.
Software
controlled
GSM_EMERGOFF
ca. 300ms ca. 900ms
Serial interfaces
ASC0 and ASC1
Undefined
Inactive
Active
GSM_VDD
ca. 60ms
GSM_TXD0
GSM_TXD1
GSM_DSR0
GSM_BATT+
GSM_IGT
min. 10ms
min.
100ms
HiZ
HiZ
Figure 3: Power-on by ignition signal
If configured to a fix baud rate, the GSM part of the XT55/56 will send the result code
^SYSSTART to indicate that it is ready to operate. This result code does not appear when
autobauding is active. See Chapter AT+IPR in [1].
In a battery operated XT55/56 application, the duration of the GSM_IGT signal must be 1s
minimum when the charger is connected and you may want to go from Charge only mode to
Normal mode.
For details
p
lease see Cha
p
ter 3.3.1.2