Users Manual

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 31 / 82
These unsolicited result codes do not appear when autobauding is active and DTE and DCE are not
correctly synchronized after start-up. The module is recommended to set to a fixed baud rate.
3.4.3. Restart
You can restart the module by driving the PWRKEY to a low level voltage for a certain time, which is
similar to the way of turning on module. In order to make the internal LDOs discharge completely after
turning off the module, it is recommended to delay about 500ms before restarting the module. The restart
timing is illustrated as the following figure.
Figure 10: Timing of Restarting System
3.5. Power Saving
Based on system requirements, there are several actions to drive the module to enter low current
consumption status. For example, AT+CFUN can be used to set module into minimum functionality mode
and DTR hardware interface signal can be used to lead system to SLEEP mode.
3.5.1. Minimum Functionality Mode
Minimum functionality mode reduces the functionality of the module to a minimum level. The consumption
of the current can be minimized when the slow clocking mode is activated at the same time. The mode is
set with the AT+CFUN command which provides the choice of the functionality levels <fun>=0, 1, 4.
 0: minimum functionality
NOTE