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Posted by SlopeFlyer33 | Oct 10, 2014 @ 05:31 PM | 1,973 Views
Smart Port Voltage Sensor: Voltage Monitor for FrSky X8R Telemetry

The Smart Port Voltage Sensor can be used to report voltages via telemetry with the X8R receiver. It utilizes a small 8-pin microprocessor to sense a voltage via an analog to digital converter and a voltage divider circuit. This board has its own 3.3v power supply and is fully self contained. There is a blue power LED that will light when connected to the Smart Port interface on the X8R receiver.

Voltage Range:
0.0 - 18.2v (will support higher voltage, but will only report the ranges listed e.g. will report 18.2v until battery voltage drops below 18.2)

NOTE: DO NOT exceed 25v or you will damage the microprocessor.

X8R Smart Port Connection:
Use the servo extension cable to connect to the Smart Port connection on the X8R (not the SBUS connection). Please verify the pinout prior to connection with specific interest on matching the positive and negative wires.
Serial to S)ignal, Positive to +, Negative to -

Analog-in Connection:
Connect to the voltage source being monitored.
Please maintain the correct polarity. One of the terminals is labeled Analog-In, this is where the + or positive terminal of the battery you are monitoring attaches. The other terminal is labeled GND, this is where the ground of the battery you are monitoring attaches... See the following diagram:

Taranis Setup:
The X8R2Analog sensor voltage will be read on Sensor Channel A2. On the Taranis Telemetry screen set the A2 channel range to 18.4 volts. Set the offset to 0 volts. Set the Low Alarm and the Critical Alarm Values to an appropriate setting for the voltage you are monitoring.

Ground Loop Stability
If there are problems with instability from a Ground Loop an alternate setup can be used:
The Ground terminal to the Voltage Source can be left disconnected with only the “Voltage In” terminal connected to the battery.
With this configuration the Taranis A2 channel range will need to be set to 14.8V for a correct reading.