.. include:: /keyword.rst

==========
Peripheral
==========

.. contents:: Sections
    :local:
    :depth: 1

.. toctree::
    :hidden:

    Genio 350-EVK <peripheral-i350-evk>
    Genio 510/700-EVK <peripheral-g700-evk>
    Genio 1200-EVK <peripheral-g1200-evk>

--------------------------------

This chapter describes the common information and instructions of Peripheral on |IOT-YOCTO|, such as listing peripheral hardware, operating devices, and so on.
Peripheral on different platforms may have some platform-specific instructions or test results.
For example, you will use different peripheral interfaces on different platforms.
Please refer to the platform-specific section for more details.

- :doc:`Genio 350-EVK Peripheral </sw/yocto/app-dev/peripheral/peripheral-i350-evk>`.
- :doc:`Genio 510/700-EVK Peripheral </sw/yocto/app-dev/peripheral/peripheral-g700-evk>`.
- :doc:`Genio 1200-EVK Peripheral </sw/yocto/app-dev/peripheral/peripheral-g1200-evk>`.
  
--------------------------------

.. note::

    All cmd operations presented in this chapter are based on the IoT Yocto v22.1, |i350-EVK-REF-BOARD|.
    You might get different operation result depends on what platform you currently use.

I2C
---

There are some I2C tools to operate I2C adapters and devices.

``i2cdetect`` will list all available I2C adapters and the I2C devices on a specific I2C bus.
You can see the connected I2C device address, e.g. 0x53, and 0x57.

.. prompt:: bash # auto

    # i2cdetect -l
    i2c-3   i2c             i2c-mt65xx                              I2C adapter
    i2c-1   i2c             i2c-mt65xx                              I2C adapter
    i2c-2   i2c             i2c-mt65xx                              I2C adapter
    i2c-0   i2c             i2c-mt65xx                              I2C adapter
    # i2cdetect -y 0
         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: -- -- -- 53 -- -- -- 57 -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    70: -- -- -- -- -- -- -- --

.. note::

    Make sure you don't have more than one device with the same address connected to the same I2C bus.
    Otherwise, the address will conflict.

``i2cdump`` will list all registers of a specific I2C device.

.. prompt:: bash # auto

    # i2cdump -y 0 0x57
    No size specified (using byte-data access)
         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
    00: a5 a5 92 00 00 81 63 02 00 0f 00 00 00 00 00 00    ???..?c?.?......
    10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
    20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
    ...

``i2cset`` and ``i2cget`` will write and read the register value.

.. prompt:: bash # auto

    # i2cget -f -y 0 0x57 0x2
    0x92
    # i2cset -f -y 0 0x57 0x2 0x93
    # i2cget -f -y 0 0x57 0x2
    0x93

Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK I2C <i2c-i350-evk>`.
- :ref:`Genio 700-EVK I2C <i2c-g700-evk>`.
- :ref:`Genio 1200-EVK I2C <i2c-g1200-evk>`.


SPI
---

First, you need to probe the SPI device manually by the command:

.. prompt:: bash # auto

    # modprobe spidev

After probing, you can find an SPI device under ``/dev``.

.. prompt:: bash # auto

    # ls -l /dev/spidev0.0
    crw------- 1 root root 153, 0 Sep 20 12:22 /dev/spidev0.0

To test the SPI device, you can use a pre-installed tool, ``spidev_test``.
It verifies that the data sent by Tx should be the same as the data received by Rx.

.. note::

    Before using ``spidev_test`` to test, SPI_MOSI and SPI_MISO should be shorted.

.. prompt:: bash # auto

    # dd if=/dev/random of=test.bin bs=96 count=1
    1+0 records in
    1+0 records out
    96 bytes copied, 0.000968692 s, 99.1 kB/s
    # spidev_test -D /dev/spidev0.0 -s 400000 -i test.bin -v
    spi mode: 0x0
    bits per word: 8
    max speed: 400000 Hz (400 kHz)
    TX | A3 62 7A EB CA 8E 69 98 1C A9 A8 E4 2C 9A 6A 0E 94 DA EC 34 84 28 FC AE 7F 27 91 E7 B9 7E D6 32  |.bz...i.....,.j....4.(...'...~.2|
    TX | 21 4A 08 0A B5 65 B3 3D D7 63 CC 6B 4C 77 A4 D4 C8 FB 57 93 B7 91 4A 34 F6 16 76 FB 72 9C C9 66  |!J...e.=.c.kLw....W...J4..v.r..f|
    TX | 43 FE E0 90 54 62 E4 BC CF BF 36 81 D4 95 BF FB EF 84 66 E1 30 E0 D2 24 E5 DD 98 24 C0 F8 A1 E3  |C...Tb....6.......f.0..$...$....|
    RX | A3 62 7A EB CA 8E 69 98 1C A9 A8 E4 2C 9A 6A 0E 94 DA EC 34 84 28 FC AE 7F 27 91 E7 B9 7E D6 32  |.bz...i.....,.j....4.(...'...~.2|
    RX | 21 4A 08 0A B5 65 B3 3D D7 63 CC 6B 4C 77 A4 D4 C8 FB 57 93 B7 91 4A 34 F6 16 76 FB 72 9C C9 66  |!J...e.=.c.kLw....W...J4..v.r..f|
    RX | 43 FE E0 90 54 62 E4 BC CF BF 36 81 D4 95 BF FB EF 84 66 E1 30 E0 D2 24 E5 DD 98 24 C0 F8 A1 E3  |C...Tb....6.......f.0..$...$....|

You can refer to the source of ``spidev_test`` `here <https://gitlab.com/mediatek/aiot/bsp/linux/-/blob/mtk-v5.10/tools/spi/spidev_test.c>`_ for how to use the SPI device.

Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK SPI <spi-i350-evk>`.
- :ref:`Genio 700-EVK SPI <spi-g700-evk>`.
- :ref:`Genio 1200-EVK SPI <spi-g1200-evk>`.

USB
---

The USB ports on the board may have different usages, such as USB master/slave, image flush port, and the console port.
Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK USB <usb-i350-evk>`.
- :ref:`Genio 1200-EVK USB <usb-g1200-evk>`.

PWM
---

Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK PWM <pwm-i350-evk>`.
- :ref:`Genio 700-EVK PWM <pwm-g700-evk>`.
- :ref:`Genio 1200-EVK PWM <pwm-g1200-evk>`.

UART
----

You can use ``sysfs`` to find out the UART devices.

.. prompt:: bash # auto

    # ls -l /sys/class/tty/ttyS*
    lrwxrwxrwx 1 root root 0 Sep 20 10:43 /sys/class/tty/ttyS0 -> ../../devices/platform/soc/11002000.uart0/tty/ttyS0
    lrwxrwxrwx 1 root root 0 Sep 20 10:43 /sys/class/tty/ttyS1 -> ../../devices/platform/soc/11003000.uart1/tty/ttyS1
    lrwxrwxrwx 1 root root 0 Sep 20 10:43 /sys/class/tty/ttyS2 -> ../../devices/platform/soc/11004000.uart2/tty/ttyS2

By default, the console log is transferred to the host through ``ttyS0``.

Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK UART <uart-i350-evk>`.
- :ref:`Genio 700-EVK UART <uart-g700-evk>`.
- :ref:`Genio 1200-EVK UART <uart-g1200-evk>`.

.. note::

    The UART DMA mode (``CONFIG_MTK_UART_APDMA``) is enabled by default.
    If you prefer not to use the DMA mode, you will need to disable it manually.

GPIO
----

You can use GPIO tools to operate the GPIO pin.

``gpiodetect`` will list all available GPIO chips.

.. prompt:: bash # auto

    # gpiodetect
    gpiochip0 [1000b000.pinctrl] (156 lines)

``gpioinfo`` will list all states of GPIO pins.

.. prompt:: bash # auto

    # gpioinfo | head
    gpiochip0 - 156 lines:
            line   0:      unnamed       unused   input  active-high
            line   1:      unnamed       unused   input  active-high
            line   2:      unnamed       unused   input  active-high
            line   3:      unnamed       unused   input  active-high
            line   4:      unnamed       unused   input  active-high
            line   5:      unnamed       unused   input  active-high
            line   6:      unnamed       unused   input  active-high
            line   7:      unnamed       unused   input  active-high
            line   8:      unnamed       unused   input  active-high
            ...

``gpioset`` and ``gpioget`` will write and read the specific GPIO pin.
If you short GPIO pin 32 and GPIO pin 34, you can set one pin and get the value back from another pin.

.. prompt:: bash # auto

    # gpioset gpiochip0 32=0
    # gpioget gpiochip0 34
    0
    # gpioset gpiochip0 32=1
    # gpioget gpiochip0 34
    1

Please refer to the platform-specific section for more details on each platform.

- :ref:`Genio 350-EVK GPIO <gpio-i350-evk>`.
- :ref:`Genio 700-EVK GPIO <gpio-g700-evk>`.
- :ref:`Genio 1200-EVK GPIO <gpio-g1200-evk>`.

Pin Header
----------

The boards have the pin header. Some follow Raspberry Pi HAT configuration and some don't.
Please refer to the platform-specific section for more details.

- :ref:`Genio 350-EVK Raspberry Pi HAT <pin-header-i350-evk>`.
- :ref:`Genio 700-EVK Pin Header <pin-header-g700-evk>`.
- :ref:`Genio 1200-EVK Pin Header <pin-header-g1200-evk>`.

.. _peripheral-uvc-gadget:

UVC Gadget
----------

This section covers the usage of UVC gadget for Genio 510/700/1200-EVK.
It includes instructions on generating the gadget node,
setting up and launching the camera, and the interaction between the PC and EVK.
This section will use the Genio 700-EVK USB port0 micro-b for demonstrating the UVC gadget example.

.. note::

    The Genio 350-EVK lacks a USB 3.0 port, so its UVC gadget may be limited by the USB 2.0 bandwidth.

Firstly, in accordance with `Linux USB gadget <https://docs.kernel.org/usb/gadget_configfs.html>`_ , UVC configuration through `Configfs <https://docs.kernel.org/filesystems/configfs.html>`_ is required. Please refer to the ``uvc.sh`` script below.

.. code-block:: bash
   :caption: `uvc.sh`
   :name: `uvc.sh`

    #! /bin/sh

    cd  /sys/kernel/config/usb_gadget/g1
    echo "" > UDC
    rm -rf configs/c.1/ffs.adb
    rm -rf configs/c.1/rndis.usb0
    echo "0x046D" > idVendor
    echo "0x087C" > idProduct
    echo "0x0010" > bcdDevice
    echo "0xef" > bDeviceClass
    echo "0x02" > bDeviceSubClass
    echo "0x01" > bDeviceProtocol
    mkdir strings/0x409
    echo "0123456789ABCDEF" > strings/0x409/serialnumber
    echo "Mediatek Inc." > strings/0x409/manufacturer
    echo "uvc gadget" > strings/0x409/product
    mkdir functions/uvc.usb0
    mkdir functions/uvc.usb0/control/header/h
    echo 3072 > functions/uvc.usb0/streaming_maxpacket
    echo 7 > functions/uvc.usb0/streaming_maxburst
    cd functions/uvc.usb0/control/
    ln -s header/h class/fs
    ln -s header/h class/ss
    cd ../../../
    mkdir -p functions/uvc.usb0/streaming/uncompressed/u/360p
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/wWidth
    640
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/wHeight
    360
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwMinBitRate
    55296000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwMaxBitRate
    55296000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwMaxVideoFrameBufferSize
    460800
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwFrameInterval
    333333
    EOF
    mkdir -p functions/uvc.usb0/streaming/uncompressed/u/720p
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/wWidth
    1280
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/wHeight
    720
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/dwMinBitRate
    147456000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/dwMaxBitRate
    147456000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/dwMaxVideoFrameBufferSize
    1843200
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/720p/dwFrameInterval
    333333
    EOF
    mkdir -p functions/uvc.usb0/streaming/uncompressed/u/1080p
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/wWidth
    1920
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/wHeight
    1080
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/dwMinBitRate
    147456000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/dwMaxBitRate
    147456000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/dwMaxVideoFrameBufferSize
    1843200
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/1080p/dwFrameInterval
    333333
    EOF
    mkdir -p functions/uvc.usb0/streaming/mjpeg/m/360p
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/wWidth
    640
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/wHeight
    360
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/dwMinBitRate
    18432000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/dwMaxBitRate
    55296000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/dwMaxVideoFrameBufferSize
    460800
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/360p/dwFrameInterval
    333333
    1000000
    5000000
    EOF
    mkdir -p functions/uvc.usb0/streaming/mjpeg/m/720p
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/wWidth
    1280
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/wHeight
    720
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/dwMinBitRate
    29491200
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/dwMaxBitRate
    29491200
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/dwMaxVideoFrameBufferSize
    1843200
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/720p/dwFrameInterval
    333333
    EOF
    mkdir -p functions/uvc.usb0/streaming/mjpeg/m/1080p
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/wWidth
    1920
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/wHeight
    1080
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/dwMinBitRate
    165888000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/dwMaxBitRate
    995328000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/dwMaxVideoFrameBufferSize
    960000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/1080p/dwFrameInterval
    333333
    EOF
    mkdir -p functions/uvc.usb0/streaming/mjpeg/m/2160p
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/bmCapabilities
    0
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/wWidth
    3840
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/wHeight
    2160
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/dwMinBitRate
    165888000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/dwMaxBitRate
    995328000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/dwMaxVideoFrameBufferSize
    960000
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/dwDefaultFrameInterval
    333333
    EOF
    cat <<EOF > functions/uvc.usb0/streaming/mjpeg/m/2160p/dwFrameInterval
    333333
    EOF
    mkdir functions/uvc.usb0/streaming/header/h
    cd functions/uvc.usb0/streaming/header/h
    ln -s ../../mjpeg/m/
    cd ../../class/fs
    ln -s ../../header/h
    cd ../../class/hs
    ln -s ../../header/h
    cd ../../class/ss
    ln -s ../../header/h
    cd ../../../control
    cd ../../../
    mkdir configs/c.1
    ln -s functions/uvc.usb0/ configs/c.1
    echo $(ls /sys/class/udc | awk 'NR==1') > UDC
    echo "uvc.sh done!"

If using a USB 2.0 port, the frame buffer should be set to 1024 to prevent insufficient bandwidth issues.

.. code-block:: bash

    echo 1024 > functions/uvc.usb0/streaming_maxpacket
    echo 1 > functions/uvc.usb0/streaming_maxburst

.. note::

	The configuration of the UVC gadget `configfs` should be tailored to specific usage requirements. Here, an executable example is provided on Genio 700-EVK.


Next, ``adb push`` this file to the Genio 700-EVK and execute it.


.. code-block:: bash

   # from PC
   adb push uvc.sh /tmp

   # from EVK
   cd /tmp
   chmod 777 uvc.sh
   ./uvc.sh

After executing ``uvc.sh`` and connecting a USB camera, the open-source example program from
https://github.com/wlhe/uvc-gadget will be utilized to display the USB camera's feed to the UVC gadget.


The generation of the gadget node can be confirmed by using ``ls /sys/class/video4linux/ -l``.
In the following example, the generated UVC gadget node is ``/dev/video7``, while the USB camera node is ``/dev/video5``.

.. code-block:: bash

    root@genio-700-evk:/mnt# ls /sys/class/video4linux/ -l
    total 0
    lrwxrwxrwx 1 root root 0 Apr 28  2022 video0 -> ../../devices/platform/soc/1a030000.jpgenc/video4linux/video0
    lrwxrwxrwx 1 root root 0 Apr 28  2022 video1 -> ../../devices/platform/soc/1a040000.jpgdec/video4linux/video1
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video2 -> ../../devices/platform/soc/14001000.mdp3-rdma0/video4linux/video2
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video3 -> ../../devices/platform/soc/18000000.vdec/video4linux/video3
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video4 -> ../../devices/platform/soc/1a020000.venc/video4linux/video4
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video5 -> ../../devices/platform/soc/11201000.usb1/11200000.xhci1/usb3/3-1/3-1.2/3-1.2:1.2/video4linux/video5
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video6 -> ../../devices/platform/soc/11201000.usb1/11200000.xhci1/usb3/3-1/3-1.2/3-1.2:1.2/video4linux/video6
    lrwxrwxrwx 1 root root 0 Dec 13 09:03 video7 -> ../../devices/platform/soc/112b1000.usb/gadget/video4linux/video7
    root@genio-700-evk:/mnt#

.. note::

    After inserting the USB camera, video5 and video6 will be generated under the USB host xHCI; use the lower number to avoid errors.

After confirming the presence of the UVC gadget node and USB camera node,
the `UVC-gadget <https://github.com/wlhe/uvc-gadget>`_ test program can be used to interconnect them.
Referring to the ``uvc-gadget -h`` command below provides insight into the option functions offered by this tool.


.. code-block:: bash

    root@genio-700-evk:/mnt# uvc-gadget -h
    Usage: uvc-gadget [options]
    Available options are
     -b             Use bulk mode
     -d             Do not use any real V4L2 capture device
     -f <format>    Select frame format
            0 = V4L2_PIX_FMT_YUYV
            1 = V4L2_PIX_FMT_MJPEG
     -h             Print this help screen and exit
     -i image       MJPEG image
     -m             Streaming mult for ISOC (b/w 0 and 2)
     -n             Number of Video buffers (b/w 2 and 32)
     -o <IO method> Select UVC IO method:
            0 = MMAP
            1 = USER_PTR
     -r <resolution> Select frame resolution:
            0 = 360p, VGA (640x360)
            1 = 720p, WXGA (1280x720)
     -s <speed>     Select USB bus speed (b/w 0 and 2)
            0 = Full Speed (FS)
            1 = High Speed (HS)
            2 = Super Speed (SS)
     -t             Streaming burst (b/w 0 and 15)
     -u device      UVC Video Output device
     -v device      V4L2 Video Capture device
    root@genio-700-evk:/mnt#


Here, it is necessary to specify ``-u`` and ``-v``, corresponding to the nodes of the UVC gadget and the USB camera,
and to set the resolution to 720p as well as the MJPEG decoding format.


.. code-block:: bash

   uvc-gadget -u /dev/video7 -v /dev/video5 -r 1 -f 1 -s 1


It's important to know which UDC port the UVC gadget is bound to, which can be checked using ``cat /sys/kernel/config/usb_gadget/g1/UDC``.


.. code-block:: bash

    root@genio-700-evk:/mnt# cat /sys/kernel/config/usb_gadget/g1/UDC
    112b1000.usb

Here, ``112b1000.usb`` refers to the Genio 700-EVK USB port0 micro-b. By connecting it to the PC using an A-to-B cable, the UVC camera can be viewed on the PC using the built-in Windows Camera Preview app.


.. figure:: /_asset/sw_yocto_app-dev_peripheral_peripheral-common_uvcgadget_example.png
    :align: center
    :width: 900px