M20 Hardware Design
current consumption may rise up to 1.6A. If the power voltage drops below 3.4V, the module may
be switched off. The PCB traces from the VBAT pads to the power source must be wide enough
to ensure that there isn’t too much voltage drop occur in the transmitting burst mode.
3.3.3 Monitoring power supply
To monitor the supply voltage, you can use the “AT+CBC” command which include three
parameters: charging status, voltage percent and voltage value (in mV). It returns the battery
voltage 1-100 percent of capacity and actual value measured between VBAT and GND.The
voltage is continuously measured at 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 power down scenarios
3.4.1 Turn on
The module can be turned on by various ways, which are described in following chapters:
z
Via PWRKEY pin: start normal operating mode
(please refer to chapter 3.4.1.1)
z
Via RTC interrupt: start ALARM mode
(please refer to chapter 3.4.1.2)
Note: AT command can be sent to the module after it is powered on and Unsolicited Result Code
“RDY” is received from the serial port0. However if the module was set to autobauding mode,
the URC “RDY” wouldn’t be received from the serial port of the module. AT command can be
sent to the module 2-3 seconds after the module is powered on. You can use “AT+IPR=x;&W”
to set a fixed baud rate and save the configuration to non-volatile flash memory. After this
configuration, the URC “RDY” should be received from the serial port0 every time when the
module is powered on. Refer to Chapter “AT+IPR” in document [1].
3.4.1.1 Turn on module using the PWRKEY pin (Power on)
Customer’s application can turn on the module by driving the pin PWRKEY to a low level voltage
for some time and then releasing it. An open collector driver circuit is suggested to control the
PWRKEY. A simple reference circuit is illustrated in Figure 5.
M20_HD_V1.01
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Quectel
