User's Manual

M10 Hardware Design
M10_HD_V3.0 - 28 -
C1>=100uF; C2=0.1uF~1uF; C3=10pF; C4=33pF
Figure 5: Reference circuit of the VBAT input
3.3.3. Monitor power supply
To monitor the supply voltage, you can use the “AT+CBC” command which includes three
parameters: charging status, remaining battery capacity and voltage value (in mV). It returns the
0-100 percent of battery capacity and actual value measured between VBAT and GND. The
voltage is continuously measured at an interval depending on the operating mode. The displayed
voltage (in mV) is averaged over the last measuring period before the “AT+CBC” command is
executed.
For details, please refer to document [1].
3.4. Power up and down scenarios
3.4.1. Power on
The module can be turned on through the two ways, which are described in following chapters:
 Via PWRKEY pin: start normal operating mode (please refer to chapter 3.4.1.1);
 Via RTC interrupt: start ALARM mode (please refer to chapter 3.4.1.2).
Note: The module is set to autobauding mode (AT+IPR=0) in default configuration. In the
autobauding mode, the URC “RDY” is not sent to host controller after powering on. AT
command can be sent to the module 2-3 seconds after the module is powered on. Host controller
should firstly send an “AT” or “at” string in order that the module can detect baud rate of host
controller, and it should send the second or the third “AT” or “at” string until receiving “OK”
string from module. Then an “AT+IPR=x;&W” should be sent to set a fixed baud rate for