4.9 QR Code Recognition

4.9.1 Algorithm

It can recognize a simple QR code and return its coordinates, size and text content, but the QR code information should not exceed 25 characters. ASCII code characters can be displayed on the screen. Note that if it is a Chinese QR code, it cannot be displayed, but the recognition result can still be read by the main control.

4.9.2 Code Blocks

  1. a63 reads the coordinates x, y and sizes w, h of the QR code, as shown in the following table:

    Parameter

    Attribute

    x-coord

    QR code central coordinate x

    y-coord

    QR code central coordinate y

    width

    QR code width w

    height

    QR code height h

  2. a64 reads the content stored in the QR code, such as “Red”, “Green” …

4.9.3 Generate a QR Code

We provide 5 paper QR code cards, with the contents of “Red”, “Green”, “Blue”, “White”, “Black” respectively.

If these QR codes do not meet your needs, you can search for “QR code generation for free” in your browser. There will be many links for generating QR codes online. Just find the one you like and use it. Here we also provide a generator:

Online QR code generator

After entering the link:

① Select the TEXT format

② Input the text to be generated (no Chinese characters, no more than 25 characters)

③ Click to generate a QR code

④ Download the QR code image

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4.9.4 Test Code

  1. In the code start-up, set the serial port baud rate to 9600, and then set the communication mode of the AI vision module to I2C, and finally set it to run in QrCode mode.

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  1. The if block determines the number of detections. Only when the number of detections is greater than 0 will the data be output. Note to choose QrCode.

Complete code:

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4.9.5 Test Result

After uploading the code, the AI vision module will detect the area captured by the camera. If there is a QR code, it will be recognized and its size and content will be printed on the serial monitor.

4.9.6 Extension Gameplay

Multifunctional instruction card

  • Game rule: Generate many QR codes whose content is not website address but direct control instructions (such as LED_ON, SERVO_90). Scan these QR codes to directly control the hardware to perform corresponding actions.

  • Practice: Program and parse the scanned string, and directly execute them as command. This is a hardware control method without keyboard input.