Common questions

Please look through this book first, the content in the following can be traced in the book.

Choose OpenMV3 M7 or OpenMV2 M4？

Choose OpenMV3 M7 directly.

What's the difference between OpenMV3 M7 and OpenMV2 M4？

• perpheral is different，look it through ：all kinds of perpheral in pyb

Emphasis:OpenMV2 can't use apriltag in arithmetic while OpenMV3 can. In support of the biggest resolution response:OpenMV2 320x240；OpenMV3 640x480.

Is OpenMV open source？

Yes，totally open source，github：https://github.com/openmv/openmv

What if there is something wrong with the operational process ？

First, update IDE and firmware to the latest version.

See Common code errors
See common faults

How to view the version of firmware?

After connecting OpenMV, look at the arrow in the following picture.

How to upgrade firmware?

See upgrade firmware

How to open terminal/check the content of print.

See Quickstart in 10 minutes

What's the difference between OpenMV and OpenCV？

OpenMV is a hardware project，integrating arithmetic ofimage，hardware is used specially(open source).

OpenCV is a universal software project which need the support of operating system since it need transplant and cut out quite an amount of code when run inflush bonding.

If the arithmetic of OpenMV belongs to transplant from OpenCV？

No, arithmetic is entirely rewritten since OpenMV is designed for computer and not suitable for flush bonding to use.

What's the advantage of OpenMV compared with Raspberry Pi?

• Consumptiom, OpenMV only need 100MA or140MA while running arithmetic. You can use USB to supply power. Raspberry Pi need 700MA,and can’t use USB to supply power.

• Easy to develop. The development of OpenMV is similar with Arduino, just need ten minutes to run. Raspberry Pi need install OpenCV, Numpy and any other software without IDE.

• FPS

Of course, performance is a shortcoming.

What kind of language does OpenMV use to programme?

python,be specific,is MicroPython.See The background knowledge of Python

Can OpenMV programme in language C ？Can it use IAR or Keil to programme？

You can use language C, but there is no need using Python is beneficial .If want compile the arithmetic at the bottom. See add arithmetic to source code

You can't use IAR or Keil to programme since OpenMV is based on project MicroPython.If use IAR or Keil, it is like give up project OpenMV, then you need to start over.

How to compile the firmware of OpenMV?

见：Compiling firmware

GCC on Ubuntu。

Can the firmware of OpenMV compile under Windows/IAR/Keil？

No. Please use Ubuntu and GCC.there is no recommendation doing the work in Windows.

Will it run slowly if OpenMV use MicroPython？

Indeed, it will be a little bit slower than use language C ,however,it won't be much slower.

• The algorithm of the kernel code is writen in C language.
• The first time you run, your script will be compiled as bytecode automatically by MicroPython（just like your computer）

Can OpenMV run the code off-line？

Yes, see: Quickstart in 10 minutes

Is the development of OpenmMV difficult?

It is not so hard since it like lighten a LED in Arduino. The first Hello World will cost less than ten minutes.

If want to track a small ball, just run the example code which cost less than five minutes.

Is Python difficult?

Python is praised as one of the most easy language to control.

• If have some experience of program like C/C++/Java(or any other language) before, recommend that 廖雪峰的Python教程

• If don’t have any experience of program before, recommend that 笨方法学Python

What if I can’t write logic? Namely write two functions toether.

This kind belongs to which has no experience of program. Recommend that 笨方法学Python

Here are two options：

• I won’t learn it any more, I choose to pay some money to find someone else to develop.
• Acquire the knowledge of program(not just learn Python)
  • Look through笨方法学Pythonfirst。
  • Learn more examples to find out using method of varieties of module.
  • Sort out your own logic of need.

May I use the library sunch as NumPy, PIL？

No, you can’t use it on MicroPython as a result of that these librarys are from Cpython.

Can OpenMV run neural network(NN)/deep learning？

Oh, no, these applications with giant operand, recommend that Jetson of nvidia.

What’s OpenMV’s resolution?？

300 thousand ，OV7725。 Usually use it on the procedure：

• QQVGA: 160x120
• QVGA: 320x240

Max support：

• VGA: 640x480

Annotation: VGA multicolor is a compressed format, don’t in support of image algorithm.

Can OpenMV use high resolution？

No。

• Limitation of photosensitive element.
• Limitation of OpenMV’s operational speed
• OpenMV has low memory，only 512KB

OV2640 version can have high resolution, can’t it？

Indeed, there is beta version before, but something goes wrong which leads to no more using any longer.

• Software BUG（waiting to add）
• Even use this chip, that is compressed format MJPG(such as 640*480) under high pixel. It can’t process image algorithm only to transmit and display.

Why not using the element with higher pixel？

• Cost .If need to handle 1024*768, which will contribute to more memory and the better performance of processor.
• Complexity of algorithm(waiting to add)
• There is not so much benefit as you concerned in machine vision.
• If have higher demand to pixel, you can use Raspberry Pi or PC.

Is OpenMV3’s sensor changeable？

No.

• Without any other sensor’s drive.
• Sensor is BGA and it's SMT on PCB which is unchangeable.
• There is no way you can use higher pixel on OpenMV project.

Can OpenMV use dual camera ？

No.

Can OpenMV use external camera？Such as USB camera。

No.

What’s the FPS of OpenMV？

How far is the identification distance of OpenMV？

Standard lens：

Object whose size is similar with ping-pong ball：0.5m~1m。

Face detection：1m

See：Background knowledge of image processing

Is the lens of OpenMV changeable?

Yes, standard M12 size lens.

What’s the difference between different lens？

See:Background knowledge of image processing

How far can telephoto lens look to?

Object whose size like ping pong ball：3m。

See:background knowledge of processing image.

What algorithms does OpenMV have?

• Color tracking
• Find qrcodes
• Face tracking
• Find lines
• Template macthing
• Keypoints detection
• Eyes detection
• HAAR，LBP，HOG
• Save image
• Record vidieo
• Edge detection
• Iris detection
• Find line
• Optical flow
• Face detection
• AprilTag

See:OpenMV’s Approach of Picture Processing

Various of algorithms docs，see ：image machine vision

Can OpenMV detect number？

Template matching ，see :Template matching

Can OpenMV detect letter？

Template matching ，see :Template matching

Can OpenMV detect Chinese character？

Template matching ，see :Template matching

Can OpenMV detect shape？

模板匹配，见：模板匹配

Can OpenMV find face？

Yes.

Can OpenMV detect qrcode？

Yes ，see :Scanning and identifying codes

Can OpenMV detect laser spot？

Yes ,color detection。

Can OpenMV communicate with other chips？

Yes Serial communication Ⅰ
Serial communication Ⅱ

Can OpenMV communicate with Arduino/51/STM32？

Yes Serial communication Ⅰ
Serial communication Ⅱ

How should OpenMV communicate with PLC？

RS232 and RS485 are serials of PLC. Using one module TTL-RS232or TTL-RS485,then that’s it. Serial communication Ⅰ
Serial communication Ⅱ

Can OpenMV communicate with computer？

Yes. Use serial or USB to communicate

USB：USB-VCP docs

Can OpenMV drive Stepping motor/DC motor/Servo?

Yes ,see：all kinds of motor

How many servos can OpenMV drive?

OpenMV2 two，OpenMV3 three。
Using PCA9685 makes it expand to 16 circuit or even more.

See ：all kinds of motor

Can OpenMV be used in autopilot？

Yes with serial. Furthermore, There are pact OpenMV and MavLink.

How OpenMV supply power？

Choose one of the following, you can also supply power at the same time.

• USB supply power directly.
• Vin-GND link with voltage at an arrange from 3.7V to 5V，recommend 5V

What’s for the OpenMV’s pin of 3.3V?

是电压的3.3V输出端，可以给其他的模块供电。

Can OpenMV use li battery to supply power?

Yes, li battery is usually 3.7V.

What’s OpenMV’s working voltage?

3.3V，但是5V容忍（如果有5V的输入，芯片可以识别到1并正常工作，但是输出始终为3.3V）。

Why is it so hot when OpenMV run the code?

It is okay about 50°.

How many pins does LCD take up?

P0, P2, P3, P6, P7, P8

See :OpenMV’s accessories

Is LCD use SPI？

Yes

What’s LCD’s resolution？

sensor.QQVGA2: 128x160

Can it transmit wireless image ？

Yes，use WIFI shield.

See :OpenMV’s accessories

What’s the usefulness of OpenMV SDcard？

It can be used to save image.

How big is OpenMV ‘s SDcard max support?

32G