19. 摄像头¶
19.1. 使能设备树插件¶
想要使能OV5640摄像头需要打开camera的设备树插件。 如下所示：
/boot/uEnv.txt¶
1 | dtoverlay=/usr/lib/linux-image-5.4.47-imx8mm/freescale/overlays/imx8mm-fire-cam.dtbo
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19.2. v4l-utils工具使用¶
v4l-utils工具安装
1 | sudo apt install v4l-utils
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查看可用的视频设备，其中/dev/video0对应OV5640的物理设备
1 2 3 4 5 6 | #执行命令
v4l2-ctl --list-devices
#显示信息如下
i.MX6S_CSI (platform:32e20000.csi1_bridge):
/dev/video0
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查看摄像头所有参数
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | #执行命令
sudo v4l2-ctl -d /dev/video0 --all
#显示信息如下
Driver Info:
Driver name : mx6s-csi
Card type : i.MX6S_CSI
Bus info : platform:32e20000.csi1_bridge
Driver version : 5.4.47
Capabilities : 0x84200001
Video Capture
Streaming
Extended Pix Format
Device Capabilities
Device Caps : 0x04200001
Video Capture
Streaming
Extended Pix Format
Priority: 0
Video input : 0 (Camera: ok)
Format Video Capture:
Width/Height : 0/0
Pixel Format : ''
Field : Any
Bytes per Line : 0
Size Image : 0
Colorspace : Default
Transfer Function : Default (maps to Rec. 709)
YCbCr/HSV Encoding: Default (maps to ITU-R 601)
Quantization : Default (maps to Full Range)
Flags :
Crop Capability Video Capture:
Bounds : Left 0, Top 0, Width 0, Height 0
Default : Left 0, Top 0, Width 0, Height 0
Pixel Aspect: 1/1
Crop: Left 0, Top 0, Width 0, Height 0
Selection: crop, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: crop_default, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: crop_bounds, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: compose, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: compose_default, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: compose_bounds, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: compose_padded, Left 0, Top 0, Width 0, Height 0, Flags:
Selection: native_size, Left 0, Top 0, Width 0, Height 0, Flags:
Streaming Parameters Video Capture:
Capabilities : timeperframe
Frames per second: 30.000 (30/1)
Read buffers : 0
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查看摄像头所支持的分辨率
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | #执行命令
sudo v4l2-ctl --list-formats-ext -d /dev/video0
#显示信息如下
ioctl: VIDIOC_ENUM_FMT
Type: Video Capture
[0]: 'YUYV' (YUYV 4:2:2)
Size: Discrete 640x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 320x240
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 720x480
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1280x720
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 1920x1080
Interval: Discrete 0.033s (30.000 fps)
Size: Discrete 2592x1944
Interval: Discrete 0.067s (15.000 fps)
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19.3. 安装gstreamer¶
可以使用gstreamer对摄像头做个简单测试，安装命令如下
1 | sudo apt install libgstreamer1.0-0 gstreamer1.0-plugins-base gstreamer1.0-plugins-good gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly gstreamer1.0-libav gstreamer1.0-doc gstreamer1.0-tools
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19.3.1. 简单测试¶
使用以下命令可对摄像头进行录制视频、拍照或将摄像头的拍摄到的视频显示到显示屏上。
1 2 3 4 5 6 7 | #录制视频
#录制的视屏可以用MobaXter软件通过ssh连接到开发板，将视屏下载到pc，用potplayer播放
sudo gst-launch-1.0 -v v4l2src device=/dev/video0 ! "video/x-raw, format=(string)YUY2, width=(int)640,height=(int)480, framerate=(fraction)30/1" ! videoconvert ! avimux ! filesink location=webcam.avi
#拍照 (拍照命令对使用OV5640摄像头有问题，建议使用 USB免驱摄像头 章节部分的用的摄像头）
sudo gst-launch-1.0 v4l2src num-buffers=1 device=/dev/video0 ! jpegenc ! filesink location=picture.jpg
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19.4. 摄像头设备树插件¶
野火IMX8M MINI提供了很多的设备树插件源码，若想要修改不同的引脚作为v5640摄像头的引脚， 可参考:
设备树插件为 imx8mm-fire-cam.dtbo ，源码如下所示
arch/arm64/boot/dts/freescale/overlays/imx8mm-fire-cam-overlay.dts¶
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 | /dts-v1/;
/plugin/;
#include "../imx8mm-pinfunc.h"
#include "dt-bindings/gpio/gpio.h"
#include "dt-bindings/clock/imx8mm-clock.h"
/ {
fragment@0 {
target = <&csi1_bridge>;
__overlay__ {
fsl,mipi-mode;
status = "okay";
port {
csi1_ep: endpoint {
remote-endpoint = <&csi1_mipi_ep>;
};
};
};
};
fragment@1 {
target = <&mipi_csi_1>;
__overlay__{
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
port {
/* must before mipi1_sensor_ep */
csi1_mipi_ep: endpoint@0 {
remote-endpoint = <&csi1_ep>;
};
mipi1_sensor_ep: endpoint@1 {
remote-endpoint = <&ov5640_mipi1_ep>;
data-lanes = <2>;
csis-hs-settle = <13>;
csis-clk-settle = <2>;
csis-wclk;
};
};
};
};
fragment@2 {
target = <&i2c2>;
__overlay__{
clock-frequency = <400000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c2>;
status = "okay";
#address-cells = <1>;
#size-cells = <0>;
ov5640_mipi: ov5640_mipi@3c {
compatible = "ovti,ov5640_mipi";
reg = <0x3c>;
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_csi_pwn>, <&pinctrl_csi_rst>;
clocks = <&clk IMX8MM_CLK_CLKO1>;
clock-names = "csi_mclk";
assigned-clocks = <&clk IMX8MM_CLK_CLKO1>;
assigned-clock-parents = <&clk IMX8MM_CLK_24M>;
assigned-clock-rates = <24000000>;
csi_id = <0>;
pwn-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
rst-gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
mclk = <24000000>;
mclk_source = <0>;
port {
ov5640_mipi1_ep: endpoint {
remote-endpoint = <&mipi1_sensor_ep>;
};
};
};
};
};
fragment@3 {
target= <&iomuxc>;
__overlay__{
pinctrl_i2c2: i2c2grp {
fsl,pins = <
MX8MM_IOMUXC_I2C2_SCL_I2C2_SCL 0x400001c3
MX8MM_IOMUXC_I2C2_SDA_I2C2_SDA 0x400001c3
>;
};
pinctrl_csi_pwn: csi_pwn_grp {
fsl,pins = <
MX8MM_IOMUXC_GPIO1_IO07_GPIO1_IO7 0x19
>;
};
pinctrl_csi_rst: csi_rst_grp {
fsl,pins = <
MX8MM_IOMUXC_GPIO1_IO06_GPIO1_IO6 0x19
>;
};
};
};
};
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19.5. USB免驱摄像头¶
当插入UVC(全称USB Video Class)免驱摄像头时, 内核将会打印信息，使用lsusb再次查看lsusb设备时可发现多了一个新的USB设备。 同时在 /dev/ 目录下将多出新的video设备，其中 /dev/video2 则为USB摄像头设备， 不同板子的摄像头设备文件可能不同。
本实验使用的设备为USB免驱摄像头
注意得支持USB2.0的，可以先在PC上的ubuntu测试可以用再在板子上试。
1 2 3 4 5 6 7 8 9 | root@lubancat:~# lsusb
Bus 001 Device 003: ID 05a3:9230 ARC International Camera
Bus 001 Device 002: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root@lubancat:~# ls -l /dev/video*
crw-rw---- 1 root video 81, 0 2月 14 2019 /dev/video0
crw-rw---- 1 root video 81, 1 2月 14 2019 /dev/video1
crw-rw---- 1 root video 81, 2 2月 14 2019 /dev/video2
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若提示找不到lsusb命令，可使用 sudo apt install usbutils 安装usbutils。
关于USB摄像头的相关操作与章节前面介绍的OV5640摄像头控制方式完全相同，请参照章节前面说明。