User's Manual

GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 33 / 88
If the module has been set by the command with AT+CFUN=4, the RF function will be disabled, but the
UART port is still active. In this case, all AT commands related with RF function will be not available.
After the module is set by AT+CFUN=0 or AT+CFUN=4, it can return to full functionality by AT+CFUN=1.
For detailed information about AT+CFUN, please refer to the document [1].
3.5.2. SLEEP Mode
The SLEEP mode is disabled by default. You can enable it by AT+QSCLK=1. On the other hand, the
default setting is AT+QSCLK=0 and in this mode, the module cannot enter SLEEP mode.
When the module is set by the command with AT+QSCLK=1, you can control the module to enter 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 module will enter SLEEP mode automatically.
In this mode, the module can still receive voice, SMS or GPRS paging from network, but the UART port
does not work.
3.5.3. Wake up Module from SLEEP Mode
When the module is in the SLEEP mode, the following methods can wake up the module.
 If the DTR Pin is set low, it would wake up the module from the SLEEP mode. The UART port will be
active within 20ms after DTR is changed to low level.
 Receive a voice or GPRS data from network wakes up module.
 Receive an SMS from network wakes up module.
DTR pin should be held at low level during communication between the module and DTE.
3.5.4. Summary of State Transition
Table 5: Summary of State Transition
Current Mode
Next Mode
Power Down
Normal Mode
Sleep Mode
Power Down
Use PWRKEY
NOTE