Microduino Module BM Shield is a single lithium battery microusb charging and discharging management module, which is used with the cooperation of Microduino-Module_BM_Li-ion, and it has functions such as under voltage and changing and output indicator.
Charging and discharging management, and charging indicator and under-voltage indicator；
Small, cheap, flexible and open；
Look at the interfaces of the module at first：
A two dial switch, which is used to control whether output voltage（5V and 3.3V）；
A microusb interface, which is used to supply power or charge the lithium battery；
There is a double color indicating light on both sides. The left is used as the voltage indicator, and the right is used as the power supply indicator；
A 1.27-spacing 4Pin interface （which is connected to "VUSB","SWI","BAT" and "GND" of Microduino-Module BM Li-ion,correspondingly）；