ArduCAM OV7251 User manual

OV7251 MIPI Camera Module
0.31MP Monochrome Global Shutter Camera
Module Datasheet
Rev 1.0, March 2019

0.31MP OV7251 MIPI CAMERA MODULE
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Table of Contents
1 Introduction.............................................................................................................................2
2 Key Specifications...................................................................................................................3
3 Block Diagram ........................................................................................................................3
4 Application..............................................................................................................................4
5 Pin Definition ..........................................................................................................................4
6 Mechanical Dimension ...........................................................................................................5
7 Installation for RPi.................................................................................................................6
7.1 Hardware.............................................................................................................................6
7.2 Camera Driver....................................................................................................................6
7.2.1 Important Note...................................................................................................................6
7.2.2 Auto-Install .........................................................................................................................6
7.2.3 Manual Install.....................................................................................................................7
7.3 VLC Player Demo...............................................................................................................8
7.3.1 Download the VLC player.................................................................................................8
7.3.2 Run the VLC player...........................................................................................................8
7.3.3 V4L2 Control Functions ....................................................................................................9

0.31MP OV7251 MIPI CAMERA MODULE
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1 Introduction
The Arducam monochrome (B&W) global shutter VGA resolution OV7251 MIPI camera module
is mainly designed for Raspberry Pi boards, and it can be connected directly to RPi’s CSI-2
camera interface without additional hardware. This camera is based on a 1/7.5-inch Omnivision
OV7251 image sensor which adopts OmniPixel3-GS technology to provide full-frame,
sub-sampled, and windowed 8/10-bit MIPI images, and capable of operating at up to 100fps in
VGA resolution with complete user control over image quality. The global shutter technology
allows to reduce or eliminate unwanted image artifacts, which occur with traditional rolling
shutter image sensors as a result of motion during image capture. The sensor's global shutter and
excellent low-light sensitivity allow it to be used for any application that needs gesture detection,
head and eye tracking, and depth and motion detection.
Leveraging the industry's smallest global shutter pixel, the black and white OV7251 is capable of
capturing VGA (640x480) resolution video at 100 frames per second (fps), QVGA (320x240) at
180 fps with binning, and QQVGA (160x120) at 360 fps with binning and skipping. The
OV7251's high frame rates make it an ideal solution for low-latency machine vision applications.
For Raspberry Pi platform, Arducam developed a proprietary camera driver which is V4L2
compliant and provides friendly compatibility to off-the-shelf video capture/playback software
like VLC player or OpenCV image processing tools. The driver also provides V4L2-ctrl functions
like manual exposure/gain, mirror/flip controls, and even the low-level sensor register access
controls. Please note that this camera and RPI driver doesn’t support ISP functions like AEC/AGC
etc., and does not support hardware JPEG/H.264 encoding. It is useful for advanced users who
need high frame rates and unprocessed RAW video for machine vision and is capable of doing
image processing using OpenCV.
This MIPI camera module can be used on other ARM, FPGA, DSP, or Nvidia TX1/TX2 hardware
platform as well.

0.31MP OV7251 MIPI CAMERA MODULE
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2 Key Specifications
Parameter
Typical Value
Sensor
Monochrome global shutter OV7251
Pixel Size
3μm x 3 μm
Active array size
640*480
Optical Size
1/7.5 inch
EFL
1.3
F.NO
2.2
FOV
D86.5⁰/H72.9⁰/V57.7⁰
Build-in IR cut filter
650nm
Focusing Range
65mm ~ infinite
Output interface
1-lane MIPI serial output
Output formats
8/10-bit BW RAW
Maximum image transfer rate
640 x 480: 100 fps
Board Size
40mm x 40mm
3 Block Diagram

0.31MP OV7251 MIPI CAMERA MODULE
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4 Application
➢Cellular phones
➢Toys
➢Tablets
➢Machine vision
➢ARM/FPGA/DSP based platforms
5 Pin Definition
The OV7251 module uses the standard Raspberry Pi camera pinout. The pin number is listed
below.
Table 1 J1 Connector Pin Definition
Pin No.
PIN NAME
TYPE
DESCRIPTION
1
DGND
Ground
Power ground
2
MDN0
Output
Pixel Data Lane0 Negative
3
MDP0
Output
Pixel Data Lane0 Positive
4
DGND
Ground
Power ground
5
MDN1
Output
Pixel Data Lane1 Negative
6
MDP1
Output
Pixel Data Lane1Positive
7
DGND
Ground
Power ground
8
MCN
Output
Pixel Clock Output Form Sensor Negative
9
MCP
Output
Pixel Clock Output Form Sensor Positive
10
DGND
Ground
Power ground
11
POWER-EN
Output
Power Enable
12
LED-EN
I/O
Led Enable
13
SCL
Input
SCCB serial interface clock input
14
SDA
I/O
SCCB serial interface data I/O
15
VCC
Power
3.3V Power supply
Table 1 J2 Connector Pin Definition
Pin No.
PIN NAME
TYPE
DESCRIPTION
1
FSIN
Input
Frame Sync Input
2
STROBE
Output
LED Strobe Output
3
GND
Ground
Ground
J2

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6 Mechanical Dimension

0.31MP OV7251 MIPI CAMERA MODULE
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7 Installation for RPi
7.1 Hardware
For RPi 1B/2B/3B/3B+ boards, please connect 15pin to 15pin FPC cable on each side.
For RPi Zero or RPi compute module, please connect the FPC cable 22pin side to RPi and 15pin
side to the camera board.
7.2 Camera Driver
7.2.1 Important Note
The camera driver should match your current Raspbian OS kernel version.
For Raspberry Pi A/A+, B/B+, Pi Zero/W, Compute module V1, you need pi1 suffix version driver,
for Raspberry pi 2B/3B/3B+, Compute module V3, you need pi3 suffix version driver.
7.2.2 Auto-Install
Run the bash script ./preprocess.sh, and choose yes to reboot. This step is only needed for once.
After the reboot, run the bash script ./loaddriver.sh with the RPI board version parameter. This
step should be done every time you reboot the Raspbian OS. For example:
./loaddriver.sh pi1
Or
./loaddriver.sh pi3

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7.2.3 Manual Install
Manual install the driver is explained here if you want to investigate the details or fix the problem
during the driver installation.
Add the following code to the last line of /boot/config.txt file
dtparam=i2c_vc=on
Save the file and probe the i2c driver using the command below:
sudo modprobe i2c-dev
Compile the device tree for the OV7251 camera
sudo dtc -I dts -O dtb -o /boot/overlays/arducam-ov7251.dtbo arducam-ov7251.dts
Add the following code to the last line of /boot/config.txt file, only oneArducam camera driver
allowed here.
dtoverlay=arducam-ov7251
Save the /boot/config.txt then reboot. The above steps only need to be done for once.
Every time you reboot the board or run after raspivid/raspistill command, you have to run the
following commands
sudo chmod +x camera_i2c
sudo chmod +x rpi3-gpiovirtbuf
./camera_i2c
Install the kernel driver using the following command
./loaddepends.sh
sudo insmod arducam-ov7251-v4l2-pi3.ko (or sudo insmod
arducam-ov7251-v4l2-pi1.ko)
After this step, you should find a new video device like /dev/video0.

0.31MP OV7251 MIPI CAMERA MODULE
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7.3 VLC Player Demo
7.3.1 Download the VLC player
You can download the vlc player (sudo apt-get install vlc) to open the camera for fast evaluation
easily.
7.3.2 Run the VLC player
Run the VLC player by the following command
vlc v4l2:///dev/video0

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7.3.3 V4L2 Control Functions
Arducam OV7251 camera driver supports a list of V4L2 control functions, and you can check the
supported functions using the following commands:
1. Check supported resolution
v4l2-ctl --list-formats-ext
2. Check the supported controls
v4l2-ctl -l
3. Manual Exposure Setting
v4l2-ctl -c exposure=0x50
4. Manual Gain Setting
v4l2-ctl -c gain=0x02
5. Mirror
v4l2-ctl -c horizontal_flip=1
6. Flip
v4l2-ctl -c vertical_fli=1
7. Sensor Register Access
First, you have to set the address of the register to be accessed, for example, 0x0202 in our case
v4l2-ctl -c register_addr=0x0202
Read the value from 0x0202 register
v4l2-ctl -C register_val
Write the value to 0x0202 register
v4l2-ctl -c register_val=0x01