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ModalAI Technical Docs

Unbricking Procedure for VOXL and VOXL Flight

Table of contents

  1. Overview
    1. Video Tutorial
    2. Force VOXL into fastboot
    3. Reflashing System Image after Forcing the VOXL into Fastboot
  2. Prevent Flash Corruption (i.e., Bricking)

Overview

The System Image flashing process requires the device to be in fastboot mode. The typical process uses adb to put the VOXL into fastboot mode over USB. If the device is bricked and one cannot get the VOXL into fastboot using USB, then you’d follow this process before running the install.sh script as described in the Flash System Image process.

The following VOXL add-on boards support the force fastboot mode switch:

Video Tutorial

Force VOXL into fastboot

To force the VOXL to boot into fastboot mode:

  • Power off the VOXL
  • Detach VOXL USB cable (to ensure USB is not supplying any power VOXL)
  • Attach the USB Expander and Debug Add-On board
  • Ensure the FASTBOOT labeled switch is set to on
  • Ensure the EMERG BOOT labeled switch is set to off
    • NOTE: if your board is missing the EMERG BOOT switch, this is OK as its default un-populated state is OFF
  • Power on the VOXL
  • Reattach VOXL USB cable
  • After VOXL boots up (about 5 seconds), set the FASTBOOT back to off

You can verify you are in FASTBOOT with the following command:

sudo fastboot devices

You should see an output like:

a0259b4a    fastboot

Reflashing System Image after Forcing the VOXL into Fastboot

To reflash the System Image, run the following while in Fastboot mode:

$ sudo ./install.sh -f

Flashing the System Image using install.sh is covered in this section.

Prevent Flash Corruption (i.e., Bricking)

With flash, like what is used on VOXL, removing power while the kernel is writing will result in corruption and bricking of the board. It can happen during development when a lot of changes are being made on the board and then power is removed.

Use the /data partition for file storage to avoid this issue.

Linux has a setting for how often the flash is committed to reduce the risk, but of course there could be different side effects. You can see a writeup on the topic here, as it is common in all of this type of single board computers

Your smartphone fixes this by making you press the poweroff button before shutting off power.

To prevent flash data corruption, run poweroff before removing power:

$ poweroff -f

Next: Onboard LED Control