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Glossary

Quick reference for terms and acronyms used throughout the Engicam documentation.

B

BitBake : The task execution engine at the core of the Yocto Project. It reads recipe files (.bb) and builds software packages by resolving dependencies and running the appropriate compilation steps.

bblayers.conf : A Yocto configuration file located in the build directory (conf/bblayers.conf). It lists all meta-layers that BitBake should include during a build.

Board Support Package (BSP) : A collection of software that provides support for a specific hardware platform, including the bootloader, kernel patches, device trees, and Yocto layers. Engicam provides BSPs for each SOM family.

C

CAN Bus : Controller Area Network. A serial communication protocol widely used in industrial and automotive environments. On Engicam boards it is typically accessible as can0, can1, etc.

ConnMan : Connection Manager. A network management daemon for embedded Linux. Used on some Engicam images as an alternative to systemd-networkd to configure network interfaces, accessible via the connmanctl command-line tool.

D

DDR : Double Data Rate memory. Refers to the SDRAM type used by a SOM (e.g. DDR3, DDR4, LPDDR4). Some Engicam modules are available in different DDR size variants (1 GB / 2 GB / 4 GB) selectable at build time via UBOOT_CONFIG.

devtool : A Yocto command-line utility for developing and modifying recipes without leaving the build environment. Common operations: devtool add, devtool modify, devtool update-recipe.

Device Tree (DT) : A data structure that describes hardware to the Linux kernel. It is written in Device Tree Source (.dts) format and compiled to a Device Tree Blob (.dtb) that U-Boot passes to the kernel at boot.

DISTRO : A Yocto variable that defines the distribution configuration to use (e.g. fsl-imx-xwayland, openstlinux-weston). It determines the default features, compiler flags, and init system.

DTB : Device Tree Blob. The binary-compiled form of a .dts file, loaded by U-Boot at boot time and passed to the Linux kernel to describe the hardware.

DTS : Device Tree Source. The human-readable source file (.dts or .dtsi) describing hardware peripherals and their configuration.

DTSI : Device Tree Source Include. A .dtsi file contains shared hardware description fragments (SoC-level or board-level) included by one or more .dts files, avoiding duplication across similar boards.

E

eMMC : embedded MultiMediaCard. NAND flash storage soldered directly on the SOM. It appears as /dev/mmcblk0 or /dev/mmcblk2 depending on the platform. Used as the main persistent storage on most Engicam modules.

G

GDB / GDBServer : GNU Debugger. GDB is the standard Linux debugger for compiled applications. GDBServer is a lightweight counterpart that runs on the target board and exposes a remote debugging interface, allowing a GDB session on the host to step through code over Ethernet or serial.

H

HDMI : High-Definition Multimedia Interface. Digital audio/video output interface available on some Engicam carrier boards (e.g. EDIMM Starterkit).

I

i.MX : NXP's family of ARM Cortex-A application processors. Models used in Engicam SOMs include i.MX6 (Cortex-A9), i.MX8M Mini and Plus (Cortex-A53/A55), i.MX91 and i.MX93 (Cortex-A55 + Cortex-M33), and i.MX95 (Cortex-A55 + Cortex-M7).

L

local.conf : A Yocto build configuration file located in conf/local.conf inside the build directory. It controls per-build settings such as MACHINE, DISTRO, PACKAGE_CLASSES, and custom overrides like UBOOT_CONFIG.

LVDS : Low-Voltage Differential Signaling. A display interface commonly used on Engicam carrier boards to connect TFT LCD panels.

M

MACHINE : A Yocto variable identifying the target hardware (e.g. imx8mp-icore, imx93-icore, stm32mp25f-icore). Each machine name corresponds to a .conf file inside the meta-layer.

meta-layer : A directory following the Yocto naming convention (meta-*) that contains recipes, configuration files, and patches. Engicam provides layers such as meta-engicam-nxp, meta-engicam-st, meta-engicam-rockchip.

MIPI-CSI : Mobile Industry Processor Interface — Camera Serial Interface. The standard serial interface used to connect camera modules to the SoC.

MTD : Memory Technology Device. The Linux subsystem that handles raw flash memory (NAND, NOR). NAND partitions appear as /dev/mtd0, /dev/mtd1, etc.

N

NAND : A type of non-volatile flash memory used on some older Engicam SOMs (e.g. Microgea MX6ULL). Accessed via the MTD subsystem and typically formatted with UBI/UBIFS.

O

OTG (USB OTG) : USB On-The-Go. Allows a USB port to act as either a host or a device. On Engicam boards it is used for entering USB recovery mode (e.g. with the NXP UUU tool) or for mass storage emulation (g_mass_storage).

OVA / OVF : Open Virtualization Appliance / Open Virtualization Format. Standard formats for distributing virtual machine images. Engicam provides a pre-configured Ubuntu development environment as a .ova file importable into VirtualBox.

P

PCIe : Peripheral Component Interconnect Express. High-speed expansion bus available on EDIMM Starterkit boards, used for adding Ethernet controllers, Wi-Fi cards, or other peripherals.

R

recipe (.bb) : A BitBake build script that describes how to fetch, configure, compile, and install a software component. Recipes are the fundamental build unit in Yocto.

repo : Google's repo tool, used to manage multi-repository projects. Engicam NXP BSPs use it to download all required source repositories with a single command.

rootfs : Root filesystem. The complete Linux filesystem image that gets flashed onto the board. In Yocto it is typically a .tar.zst archive or embedded in a .wic disk image.

S

SDK : Software Development Kit. In the Yocto context, a self-contained cross-compilation toolchain generated with bitbake -c populate_sdk. It includes the cross-compiler, target sysroot, headers, and libraries needed to build applications for the board without a full Yocto setup.

SoC : System-on-Chip. The integrated circuit that combines CPU, GPU, memory controllers, and peripherals on a single die (e.g. i.MX8M Plus, STM32MP257, RK3568).

SOM : System-on-Module. A compact board that integrates a SoC, RAM, and flash memory. Engicam SOMs (e.g. i.Core, Microgea, Smarcore) plug into carrier boards such as the EDIMM Starterkit or C.Touch.

SPL : Secondary Program Loader. The first stage of U-Boot, responsible for initializing DRAM and loading the main U-Boot binary.

SSH : Secure Shell. Encrypted remote terminal protocol used to access the board over Ethernet (ssh root@<board-ip>). Also used for file transfer via scp and sftp.

STM32MP : STMicroelectronics' family of heterogeneous microprocessors combining ARM Cortex-A application cores with ARM Cortex-M real-time cores. Engicam SOMs use the STM32MP23 and STM32MP25 series.

sysroot : A directory tree mirroring the target board's root filesystem — libraries, headers, and pkg-config files — installed on the host machine. Used by the cross-compiler to resolve dependencies when building applications for the target. Populated automatically by the Yocto SDK installer.

systemd : The init system and service manager used by Engicam Linux images. Manages services via unit files (.service), controls the boot sequence, and exposes tools such as systemctl and journalctl.

T

TFTP : Trivial File Transfer Protocol. A simple UDP-based file transfer protocol used for transferring kernel images, DTBs, and rootfs over the network during development or automated flashing.

U

UART : Universal Asynchronous Receiver/Transmitter. The hardware serial interface used as the primary debug console on Engicam boards. Typically accessed via a USB-to-serial adapter (e.g. FTDI) at 115200 baud using picocom or minicom on the host (device usually appears as /dev/ttyUSB0).

U-Boot : Universal Boot Loader. The open-source bootloader used on all Engicam platforms. It initializes hardware, selects the boot device, and loads the kernel and device tree.

UBI / UBIFS : Unsorted Block Images (UBI) is a flash management layer that sits on top of MTD. UBIFS is the filesystem built on UBI. Used on NAND flash to handle wear leveling and bad block management.

UUU : Universal Update Utility. NXP's host-side tool for flashing i.MX boards over USB in Serial Downloader mode (USB recovery mode), without requiring an SD card.

W

Wayland / Weston : Wayland is the modern Linux display server protocol that replaces X11. Weston is its reference compositor. Engicam images use either fsl-imx-wayland (Wayland only) or fsl-imx-xwayland (Wayland + XWayland for X11 compatibility).

WIC : OpenEmbedded Image Creator. Generates bootable disk images (.wic, .wic.zst, .wic.gz) ready to be written to an SD card or eMMC with dd.

Y

Yocto Project : An open-source collaboration project that provides templates, tools, and methods for creating custom Linux distributions for embedded systems. All Engicam BSPs are Yocto-based.

Z

zstd : A fast lossless compression algorithm. Engicam Yocto images are commonly distributed as .wic.zst files. Use zstdcat to decompress on the fly while flashing with dd.