Users Manual

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 27 / 82
For details, please refer to the document [1].
3.4. Power On and Down Scenarios
3.4.1. Power On
The module can be turned on by driving the pin PWRKEY to a low level
voltage. An open collector driver circuit is suggested to control the
PWRKEY. A simple reference circuit is illustrated as below.
Figure 6: Turn on the Module with an Open-collector Driver
1. M66 module is set to autobauding mode (AT+IPR=0) by default. In the autobauding mode, URC “RDY”
is not reported to the host controller after module is powered on. When the module is powered on after
a delay of 4 or 5 seconds, it can receive AT command. Host controller should first send an AT string in
order that the module can detect baud rate of host controller, and it should continue to send the next AT
string until receiving OK string from the module. Then enter AT+IPR=x;&W to set a fixed baud rate for
the module and save the configuration to flash memory of the module. After these configurations, the
URC RDY would be received from the UART Port of the module every time when the module is
powered on. For more details, refer to the section AT+IPR in document [1].
2. When AT command is responded, indicates module is turned on successfully, or else the module fails
to be turned on.
The other way to control the PWRKEY is through a button directly. A TVS component is indispensable to
be placed nearby the button for ESD protection. For the best performance, the TVS component must be
NOTES