This article is intended to help you get started with battery monitoring and the buzzer feature present in MultiWii. We’ll cover proper connections / wiring and software setup as it relates to the Lynxmotion Quadrino Nano flight controller (MultiWii compatible). MultiWii gives the user the ability to monitor the UAV’s main battery voltage (normally a LiPo battery), and trigger LEDs or an external buzzer to warn the user when the battery’s voltage has dropped below a certain level. The buzzer you choose should be sufficiently loud so you can hear it from the ground.
MultiWii Setup
There are several ways to set up MultiWii values via software, but for simplicity we suggest using the Quadrino FCT (Firmware Configuration Tool) as it will load the correct values for a 3s LiPo to the Quadrino Nano. The Quadrino FCT uses the MultiWii software at its core, but presents the user with a much more intuitive interface. The values which are loaded to the flight controller can later on be changed in the WinGUI application without the need to flash the board via the FCT.
1 – FCT Options Open the FCT application and go to the “Battery” tab which is located in the “Options” page. |  FCT – Options Page |
2 – Enable Battery Voltage Monitoring On the same page, check “Enable Battery Voltage Monitoring”. You do not need to make the physical connections yet. |  FCT – Battery Monitoring |
3 – Set values The default settings are for a 3s (11.1V) LiPo battery, but you can change the alarms set-points (number 107 will stand for 10.7V). |  FCT – Alarms Levels |
4 – Activate Buzzer In the “Misc” tab, make sure the “Buzzer” is enabled (which should automatically be enabled when “Battery Monitor” is set) |  FCT – Buzzer Options |
5 – Flash the Quadrino Nano Go to the “Flash” page and flash the Quadrino Nano with the newly added options. Ensure your Quadrino Nano is connected to the computer via USB cable. |  FCT – Flash Firmware |
6 – WinGUI Connect & Load Connect to the WinGUI application and hit “Load Defaults” in the top bar |  WinGUI – Load Default Values |
6 – WinGUI Write Settings With the values loaded, click “Write Settings” to get those settings written in the Quadrino Nano memory |  WinGUI – Write Settings |
Quadrino Nano Wiring
There are two pins associated with the battery monitoring and buzzer functions which are standard on all MultiWii based controllers. These pins can be used simultaneously depending on the setup needed but if no external buzzer is set up, only the LED labeled “LiPo Alarm” will blink when the battery is low. Connect your LiPo battery to the Quadrino Nano as in the drawing below.
- VBATT (pin 19) is the battery sensing pin on the Quadrino Nano and where you need to connect the positive terminal of your battery’s charging connector. Usually there is a resistor which needs to be added between the controller pin and the battery’s positive terminal, but we already took care of this on the Quadrino Nano PCB so you can connect a 3s LiPo battery directly.
- BUZZER (pin 20) activates the buzzer when this pin is triggered to Ground via the MultiWii software. An Arduino-based controller used with MultiWii is able to pass more current by grounding a pin than being powered from it, which is why we use the pin as the ground in this application.
Lynxmotion Quadrino Nano – VBATT & BUZZER Connection
Lynxmotion Quadrino Nano – I/O port Color Code
Additional Information:
1 – Enable Battery Voltage Monitoring Checkbox used to Enable the battery monitoring feature 2 – WARNING LEVEL First warning level; it will trigger the buzzer / LED once every 3 seconds. 3 – DANGEROUS Second warning level; the battery is almost empty and the buzzer / LED is triggered in two short bursts every 3 seconds. 4 – CRITICAL Final warning; this will cause the buzzer / LED to stay on constantly. 5 – VBATT SCALE This is used to scale the VBATT input to match the battery’s real voltage. The default value for a 3S battery would be 128 but changes can be applied if needed. Here is a simple equation to correct the scaling: New VBAT SCALE = ( GUI Vbat Scale * GUI Voltage ) / Measured Voltage |  FCT – Battery Level Indicators |
Note: The values for the the LiPo alarms can be changed in the WinGUI after if the Battery Monitoring is activated in the MultiWii board. Look for the “FC Config” tab and “Battery Monitoring” sections.
WinGUI – Battery Monitoring Options
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