OpenTX - Application Note 30
Voltage Sensor – FLVSS
Set up a FLVSS Voltage Sensor for an X4R, X6R or X8R Receiver.
The FLVSS Voltage Sensor
FLVSS means ‘FRSky LiPo battery Voltage Sensor with Smart port’. The FLVSS is connected to the X4R, X6R or X8R via their smart ports. The receiver automatically takes data from the FLVSS and transmits it continuously with any other telemetry values to the Taranis.
The total voltage and single cell voltages are displayed on the reverse side of the FLVSS when it is plugged in to the charge lead of the battery.
Taranis Set Up
The FLVSS sensor must be set up on the model Telemetry screen.
Turn power on the model receiver. On the model Telemetry screen, select the ‘Discover new sensors’ text. While selected, press the Enter key. If there are no smart port sensors plugged into the receiver, only the following sensors are found and set up.
The ‘Discover new sensors’ text is replaced with ‘Stop discovery’. Press Enter to end the discovery mode. The ‘Stop discovery’ text is then replaced with the ‘Discover new sensors’ text.
If the FLVSS is connected to the receiver smart port, the following sensor is also set up.
A new sensor must be defined to derive the lowest battery cell voltage.
Select the ‘Add a new sensor’ text and press Enter. Enter the parameters as shown in this table.
Press Exit and the following sensor is displayed on the sensor list.
Low Voltage Alarms
Four alarm types are required. Each alarm uses a logical switch to compare voltages and a special function to announce the alarm. These are the messages and file names.
To create the audio files, see Application Note 4.
Logical switches for lowest cell voltage alarm are as follows
Logical switches for the 3S battery voltage alarms are as follows.
Alternatively, logical switches for the 4S battery voltage alarms are as follows.
Note that the voltages have to be less than the reference for more than six seconds before the logical switch becomes true. This is to prevent short term high battery loads from causing alarms.
Special functions use these logical switches to play the alarm tracks as follows.
Test the alarms by flying until a low battery or low cell alarm is announced. Land and check the battery. Adjust the reference voltages if necessary.