User's Manual

GSM/GPRS/GNSS Module Series
MC20 Hardware Design
MC20_Hardware_Design Confidential / Released 34 / 95
After the GSM part is set by AT+CFUN=0 or AT+CFUN=4, it can return to full functionality mode by
AT+CFUN=1.
For detailed information about AT+CFUN, please refer to document [1].
3.4.1.2. SLEEP Mode
SLEEP mode is disabled by default. It can be enabled by AT+QSCLK=1 and the premise is that the
GNSS is powered off. The default setting is AT+QSCLK=0, and in this mode, the GSM part cannot enter
SLEEP mode.
When the GSM part is set by the command AT+QSCLK=1, you can control the part to enter into or exit
from the SLEEP mode through pin DTR. When DTR is set to high level, and there is no on-air or hardware
interrupt such as GPIO interrupt or data on UART port, the GSM part will enter into SLEEP mode
automatically. In this mode, the GSM part can still receive voice, SMS or GPRS paging from network, but
the UART port does not work.
3.4.1.3. Wake up GSM Part from SLEEP Mode
When the GSM part is in the SLEEP mode, it can be woken up through the following methods:
 If the DTR Pin is set low, it would wake up the GSM part from the SLEEP mode. The UART port will
be active within 20ms after DTR is changed to low level.
 Receiving a voice or data call from network wakes up the GSM part.
 Receiving an SMS from network wakes up the GSM part.
DTR pin should be held at low level during communication between the GSM part and the DTE.
3.4.2. Operating Modes of GNSS Part
3.4.2.1. Full on Mode
Full on mode includes tracking mode and acquisition mode. Acquisition mode is defined as that the GNSS
part starts to search satellites, and to determine the visible satellites, coarse carrier frequency & code
phase of satellite signals. When the acquisition is completed, it switches to tracking mode automatically.
Tracking mode is defined as that the GNSS part tracks satellites and demodulates the navigation data
NOTE