While using the Sphero Edu app with your RVR or RVR+, you may see warning popups. These warnings may look alarming, but they provide important information about your robot’s functionality.
There are five main warnings you may encounter:
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eFuse Warning
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Stall Protection Warning
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Temperature Warning
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Critical Temperature Warning
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Motor Fault Warning
The sections below explain each warning, what causes it, and how to resolve it.
eFuse Warning
What’s Happening:
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The eFuse warning appears when a peripheral connected to the USB or UART port draws too much current or a short occurs.
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The eFuse is a firmware-level protection that limits current to 2.15A.
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When tripped, RVR/RVR+ LEDs flash yellow, and programs in the Sphero Edu app will stop.
How to Fix It:
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Disconnect all USB and UART peripherals.
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Ensure total current draw is below 2.15A.
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Press the Reset eFuse button in the warning popup, or power cycle your RVR/RVR+.
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Reconnect peripherals once the eFuse is reset.
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The warning will continue until the underlying issue is resolved.
Stall Protection Warning
What’s Happening:
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This warning occurs when RVR/RVR+ motors stall and are temporarily disabled.
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Common causes include:
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Heavy payloads
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Driving up steep inclines
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Spinning excessively or against a surface
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Holding or restraining the treads
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Programs in the Sphero Edu app will stop if this warning appears.
How to Fix It:
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Reduce payload weight.
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Avoid steep inclines.
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Minimize spinning and driving against surfaces.
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Do not hold or restrain the treads while motors are active.
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The motors will re-enable automatically after a few seconds.
Temperature Warning
What’s Happening:
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Motors are warming up but have not yet reached a critical temperature.
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Common causes include:
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Long driving sessions without breaks
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Steep inclines
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Frequent spinning at low speeds
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Heavy payloads
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Programs will stop if this warning appears.
How to Fix It:
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Reduce payload and drive less aggressively.
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Allow RVR/RVR+ to cool before continuing.
Critical Temperature Warning
What’s Happening:
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Motors have reached a critical temperature, and RVR/RVR+ temporarily disables motor functionality.
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LEDs pulse red, orange, and yellow until the robot cools down.
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Programs will stop if this warning appears.
How to Fix It:
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Leave RVR/RVR+ powered on and wait approximately 20 minutes for it to cool.
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Once the temperature drops below the firmware threshold, the robot is ready to use.
Motor Fault Warning (Error 1705)
What’s Happening:
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This warning indicates a serious motor fault, impairing motor functionality.
How to Fix It:
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Turn off RVR/RVR+ for 20 minutes, then power it back on.
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Reconnect in the Sphero Edu app.
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If the warning occurs again, fill out this form and include the error code 1705.