Frequently Asked Questions

Why is my VMX Robotics Controller not booting properly?
The VMX Robotics Controller/Raspberry Pi system may fail to boot, not work properly, or become damaged if the power supply is not adequate. This is true even when operating a Raspberry Pi alone, but the VMX Robotics Controller is designed to ride on the Raspberry Pi and to supply the necessary 5 VDC power to it.

The VMX Robotics Controller requires 6-16 VDC input power, and although there will be some backfeed of power from the Raspberry Pi to the VMX Robotics Controller if power is supplied via the Raspberry Pi’s micro-USB port, it will not be enough to properly power the VMX Robotics Controller and will likely cause the Raspberry Pi to not function well, if at all.

The VMX Robotics Controller also has a micro-USB port, and this should not be used to power the system. The micro-USB port can pass only 500 mA of current, and this is not enough to meet the current demands of the VMX Robotics Controller and Raspberry Pi during all stages of operation, including the boot phase, especially if there are peripheral devices attached to the Raspberry Pi. Power must be supplied via the two pin connector next to the micro-USB port, from a suitable 6-16 VDC wallwart or battery, using an appropriate adapter cable.

Note that even though your adapter may say it is rated for a voltage and current sufficient for the purpose, you may still experience problems. If such is the case, users are advised to try another power supply. For example, in internal testing, a certain adjustable power supply capable of 12 VDC at 4.5 A caused the system to not boot, while switching to a 7.5 VDC source at 1 A produced a successful boot.

Boot failures may manifest as an infinitely looping partial boot up followed by a reboot, or error condition LEDs on the VMX Robotics Controller. There may be other failure modes.

Note that boot failures may also be caused by Raspberry Pi image problems or hardware failures, so some troubleshooting may be required to fully address boot problems. Before logging a support ticket for boot issues, please check the following, and provide details of the checks in the ticket:

  1. that your Raspberry Pi boot image actually works (e.g., try in another Pi known to work, try in the Pi without the VMX Robotics Controller attached, try another known valid image in the problematic Pi, etc.)
  2. that your VMX Robotics Controller is getting sufficient power (by trying alternate power supplies) on the two-pin connector.

Last Updated 4 years ago

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