← All tools

Message & Error Explainer

What an ArduPilot message means and what to do about it

Українська

The servo rail voltage is below the limit you set

Stops itBattery and power

What ArduPilot says:

On boards that measure the servo rail (the power pins of the servo outputs), the reading is below BRD_VSERVO_MIN. The message gives both numbers. The test is off while BRD_VSERVO_MIN is 0, its default, so someone has set a limit on purpose.

What to do, most likely first

  1. The servo rail has no supply: on Pixhawk-style boards it needs its own regulator (BEC).

    CheckThe first number in the message is near zero.

    FixFeed the rail from a BEC sized for your servos.

  2. The regulator sags under the servos' load, or BRD_VSERVO_MIN is above what it gives.

    FixUse a stronger regulator, or set BRD_VSERVO_MIN about 0.5 V under its real output.

Parameters to look at

ParameterWhat it is
BRD_VSERVO_MINServo voltage requirement

Where to do it:Board & Wiring Planner

The code that sends it

PreArm: Servo voltage to low (N.Nv < N.Nv)

libraries/AP_Arming/AP_Arming.cpp AP_Arming::board_voltage_checks() · Open in ArduPilot Copter-4.7.1

Written here for Copter 4.6. In the tool you choose your vehicle and version, see your own parameter values beside the ones named here, and drop a flight log to have every message in it explained.

Open it in the Message & Error Explainer