How the MicroSD card is organized

The MicroSD card in your JeVois smart camera contains all the software that runs on the smart camera's processor. This includes:

Files necessary to boot (start up) and configure low-level hardware elements, such as the DDR3 memory and microSD card drivers, and a Linux kernel.
Linux operating system, including standard Linux command-line utilities, and many libraries such as OpenCV, boost, Eigen3, etc.
JeVois machine vision modules and data.

Using your MicroSD card with a desktop or laptop computer

Modifying the contents of your MicroSD card, for example to add new machine vision modules or to get video files that were recorded by JeVois, is achieved by taking the MicroSD card out of your JeVois smart camera and connecting it to a desktop or laptop computer.

Warning: Your JeVois smart camera features a push-push MicroSD card slot. You push the card in until it clicks to load it, and you push it in again until it clicks and then ejects to unload it. Do you try to pull the MicroSD card out or you might damage the MicroSD card slot of your JeVois smart camera.

JeVois-A33 MicroSD

JeVois-Pro MicroSD

Using the MicroSD card with a computer

There are two basic ways of accessing the MicroSD card on a desktop or laptop:

Use a USB Card Reader, sold in most computer stores, and connect it to a USB port of your desktop or laptop

Use a Micro-SD to SD card adapter, and insert the SD card into your computer if it has a slot for it (e.g., Mac laptop):

MicroSD partitions and partition types

The card is organized into three partitions (logical volumes):

BOOT (DOS/Windows FAT32 format): contains files needed for startup, including Linux kernel
LINUX (Linux ext4 format, may not show up when reading MicroSD card on Windows and Mac computers): Contains Linux operating system and programs
JEVOIS (DOS/Windows FAT32 format): Contains all JeVois machine vision modules and data files, including possibly files created by the smart camera (e.g., when saving video to microSD).

Because the LINUX partition is of type ext4, which is the native file system for Linux, but is not recognized by default on Windows and Mac, when you read your MicroSD card on a Windows or Mac computer, you may not be able to see it or to access it. That is usually not a problem as only advanced hackers (who will be programming on Linux computers) would ever need to modify the contents of the LINUX partition.

For regular users, all you need is in the JEVOIS partition, as further detailed below.

Here is an example of what happens on a Mac laptop when you insert the MicroSD card: Two volumes appear, BOOT and JEVOIS, and one can browse the files in both of them. The LINUX volume does not appear on this Mac (but note that third party apps are available to allow Macs to read ext4 partitions as well).

Warning: The MicroSD card also has additional and essential "files" that are stored directly onto specific sectors (physical flash disk locations) on the card. These are bootloader (system startup) files which are the first files loaded when the JeVois embedded processor starts. Because the processor does not yet know about partitions, file systems, etc at that early startup stage, all it knows how to do is to read raw sectors from the SD card. You usually do not need to modify these special files. But beware that if you want to copy the contents of one JeVois MicroSD card to a new card, you need to do a full physical sector-by-sector copy. Instructions for how to do this are provided in How to format a new MicroSD card for JeVois.

MicroSD card contents

Here is an abbreviated tree of the files present on a typical JeVois-A33 microSD card ( JeVois-Pro is similar but not identical):

├── BOOT  ########## (16 MB FAT32 partition)
│   ├── README.txt               # information file for Windows users who may not see the JEVOIS partition
│   ├── script.bin               # low-level hardware configuration file
│   ├── uEnv.txt                 # optional command-line arguments for the Linux Kernel
│   └── uImage                   # Linux kernel


├── LINUX ########## (1 GB Linux ext4 partition)
│   ├── bin                      ### Directory for standard Unix commands
│   │   ├── ash                  # some Unix command
│   │   ├── bash                 # some other Unix command
│   │   ├── busybox              # ...
│   │   ├── cat

...

│   ├── etc                      ### Directory for Unix configuration files
│   │   ├── fstab
│   │   ├── group
│   │   ├── hostname
│   │   ├── hosts

...

│   ├── lib                      ### Directory for Unix system libraries
│   │   ├── ld-2.23.so
│   │   ├── ld-linux-armhf.so.3
│   │   ├── libatomic.so.1.2.0
│   │   ├── libc-2.23.so
│   │   ├── libcrypt-2.23.so
│   │   ├── libc.so.6
│   │   ├── libdl-2.23.so
│   │   ├── libgcc_s.so
│   │   ├── libm-2.23.so
│   │   ├── libm.so.6
│   │   ├── libnsl-2.23.so

...

│   ├── sbin                     ### Directory for system administration Unix commands
│   │   ├── arp
│   │   ├── blkid
│   │   ├── devmem
│   │   ├── fdisk
│   │   ├── freeramdisk
│   │   ├── fsck

...

│   ├── tmp                      ### Scratch directory for temporary files
│   ├── usr                      ### Directory for user Unix commands and shared data
│   │   ├── bin
│   │   │   ├── ar
│   │   │   ├── attr
│   │   │   ├── awk
│   │   │   ├── basename
│   │   │   ├── bunzip2
│   │   │   ├── bzcat

...

│   │   ├── lib                  ### Directory for Unix user libraries
│   │   │   ├── libattr.so.1.1.0
│   │   │   ├── libavcodec.so.56.60.100
│   │   │   ├── libavdevice.so.56.4.100
│   │   │   ├── libavfilter.so.5.40.101
│   │   │   ├── libavformat.so.56.40.101
│   │   │   ├── libavheap.so
│   │   │   ├── libavresample.so.2.1.0
│   │   │   ├── libavutil.so.54.31.100
│   │   │   ├── libbfd-2.25.51.so
│   │   │   ├── libbfd-2.26.1.so
│   │   │   ├── libblas.so
│   │   │   ├── libboost_atomic.so.1.61.0
│   │   │   ├── libboost_chrono.so.1.61.0
│   │   │   ├── libboost_container.so.1.61.0

...

│   │   ├── sbin
│   │   │   ├── addgroup         ### Directory for more Unix system administration commands
│   │   │   ├── adduser
│   │   │   ├── arping
│   │   │   ├── chroot

...

│   │   └── share                ### Directory for shared data used by Unix commands
│   │       ├── awk
│   │       │   ├── assert.awk
│   │       │   ├── bits2str.awk
│   │       │   ├── cliff_rand.awk
│   │       │   ├── ctime.awk
│   │       │   ├── ftrans.awk
│   │       │   ├── getopt.awk
│   │       │   ├── gettime.awk

...
│   └── var                      ### Directory for Unix system log files and other volatile files
│       ├── cache
│       ├── lib
│       │   └── misc
│       ├── lock
│       ├── log
│       ├── run
│       ├── spool
│       └── tmp



├── JEVOIS ########## (6+ GB FAT32 partition)
│   ├── config                   ### Directory for JeVois engine configuration file
│   │   ├── initscript.cfg
│   │   ├── JeVois.cmake
│   │   ├── jevois_config.cmake
│   │   ├── params.cfg
│   │   └── videomappings.cfg
│   ├── data                     ### Directory for optional user data, some JeVois modules also save outputs into it
│   ├── lib                      ### Directory for JeVois libraries, i.e., collections of shared vision algorithms
│   │   └── JeVois               # One sub-directory for each JeVois "Vendor" (provider of JeVois modules)
│   │       └── libjevoisbase.so.1.0
│   ├── modules                  ### Directory for JeVois machine vision modules
│   │   └── JeVois               # One sub-directory for each JeVois "Vendor" (provider of JeVois modules)
│   │       ├── Convert          # One directory for each module
│   │       │   ├── Convert.so   # The compiled module code that will be loaded when that module is selected
│   │       │   ├── icon.png     # Extra data about the module
│   │       │   ├── modinfo.html
│   │       │   ├── modinfo.yaml
│   │       │   └── screenshot1.png
│   │       ├── DemoArUco
│   │       │   ├── calibration.yaml
│   │       │   ├── DemoArUco.so
│   │       │   ├── icon.png
│   │       │   ├── modinfo.html
│   │       │   ├── modinfo.yaml
│   │       │   ├── screenshot1.png
│   │       │   └── screenshot2.png
│   │       ├── DemoGPU
│   │       │   ├── DemoGPU.so
│   │       │   ├── icon.png
│   │       │   ├── modinfo.html
│   │       │   ├── modinfo.yaml
│   │       │   ├── screenshot1.png
│   │       │   ├── shaders      # This module uses auxiliary files for GPU shader code
│   │       │   │   ├── blurfragshader.glsl
│   │       │   │   ├── dilatefragshader.glsl
│   │       │   │   ├── erodefragshader.glsl
│   │       │   │   ├── medianfragshader.glsl
│   │       │   │   ├── multfragshader.glsl
│   │       │   │   ├── simplefragshader.glsl
│   │       │   │   ├── simplevertshader.glsl
│   │       │   │   ├── sobelfragshader.glsl
│   │       │   │   ├── threshfragshader.glsl
│   │       │   │   ├── twirlfragshader.glsl
│   │       │   │   └── yuvfragshader.glsl
│   │       │   └── video1.mkv

...

│   │       ├── DemoSalGistFaceObj
│   │       │   ├── DemoSalGistFaceObj.so
│   │       │   ├── facedetector
│   │       │   │   ├── haarcascade_eye_tree_eyeglasses.xml
│   │       │   │   └── haarcascade_frontalface_alt.xml
│   │       │   ├── icon.png
│   │       │   ├── modinfo.html
│   │       │   ├── modinfo.yaml
│   │       │   ├── movie.avi
│   │       │   ├── screenshot1.png
│   │       │   └── tiny-dnn     # This module uses auxiliary files for neural network data
│   │       │       ├── CIFAR10
│   │       │       │   ├── batches.meta.txt
│   │       │       │   ├── data_batch_1.bin
│   │       │       │   ├── data_batch_2.bin
│   │       │       │   ├── data_batch_3.bin
│   │       │       │   ├── data_batch_4.bin
│   │       │       │   ├── data_batch_5.bin
│   │       │       │   ├── readme.html
│   │       │       │   ├── test_batch.bin
│   │       │       │   └── weights.tnn
│   │       │       └── MNIST
│   │       │           ├── t10k-images.idx3-ubyte
│   │       │           ├── t10k-labels.idx1-ubyte
│   │       │           ├── train-images.idx3-ubyte
│   │       │           ├── train-labels.idx1-ubyte
│   │       │           └── weights.tnn

...

│   │       ├── SaliencySURF
│   │       │   ├── icon.png
│   │       │   ├── images       # Images of the things this module can recognize
│   │       │   │   ├── books.png
│   │       │   │   ├── doorframe.png
│   │       │   │   ├── doorlock2.png
│   │       │   │   ├── doorlock.png
│   │       │   │   ├── lightswitch2.png
│   │       │   │   ├── lightswitch.png
│   │       │   │   ├── spot25.png
│   │       │   │   ├── spot26.png
│   │       │   │   └── usbbatt.png
│   │       │   ├── modinfo.html
│   │       │   ├── modinfo.yaml
│   │       │   ├── params.cfg
│   │       │   ├── SaliencySURF.so
│   │       │   └── screenshot1.png

...

│   ├── packages                 ### Simply copy downloaded .jvpkg files here and JeVois will unpack and install them
│   └── scripts
│       ├── astylerc
│       ├── docinstall.sh
│       ├── extract-code-snippets.pl
│       ├── jevois-modinfo.pl
│       └── list-sources.sh

...

JeVois-A33: Accessing and modifying the MicroSD while JeVois is running

JeVois-A33 JeVois v1.1

You can access the contents of the JEVOIS partition on the microSD while the card is inside your JeVois smart camera. JeVois can (on demand) make the JEVOIS partition visible to a connected host computer over USB, as a virtual USB flash drive.

To enable this feature, connect to the JeVois command-line interface (see Command-line interface user guide) and issue the command:

usbsd

You will notice that a new USB flash drive is detected by your host computer.

Note: Since being able to switch through various vision modules while changing the contents of the microSD poses some potential data consistency issues, for now, we have restricted file access over USB to only work while not streaming video. Likewise, a reboot of the JeVois camera is necessary to allow it to use any new or modified files from th ehost computer.

On Linux and with JeVois v1.2 and later, you can use host command jevois-usbsd start to instruct a connected JeVois camera to start exporting its microSD, without having to open a serial terminal application and to connect to JeVois. Likewise, you can issue jevois-usbsd stop to release the card and restart JeVois.

Typical workflow is as follows:

Connect JeVois to a host computer and let it start up.
Make sure that you are not capturing video from JeVois.
Connect to the JeVois command line interface (either using the hardware serial port, or serial over USB; see Command-line interface user guide).
When you want to modify the contents of the microSD inside JeVois, issue the usbsd command. The virtual USB flash drive will appear on your host computer.
With JeVois v1.3 and later, you do not need to open a serial terminal and type into it, you can instead use new host command jevois-usbsd start directly from any Linux shell.
Add/modify/remove files. This includes:
- modify configuration or parameter files in JEVOIS:/config
- edit a module written in Python, under JEVOIS:/modules
- add any data, e.g., training images for the ObjectDetect module
- retrieve any data, e.g., video files recorded by JeVois
- compile and install a new C++ module using ./rebuild-platform.sh --microsd
When you are done, properly eject the virtual USB drive (drag to trash, click eject button, etc). JeVois will detect this and will automatically restart and then be able to use the new or modified files. You should see the following on the JeVois LED:
- Blinks off - shutdown complete
- Solid green - restarting
- Orange blink - camera sensor detected
- Solid orange: ready for action

Note that JeVois v1.3 adds an even simpler way to install new machine vision modules: ./rebuild-platform.sh --live, which will first issue a jevois-usbsd start to tell JeVois to export its microSD, will install the module, and will then issue a jevois-usbsd stop to restart JeVois.