Thursday, June 13, 2024

Barcode And QR Code Scanner Reference Design

This design is a practical example of using the Atmel SAM4S microcontroller for QR code decoding, demonstrating its capabilities and providing a foundation for further development in similar applications.

Barcodes are a series of lines with varying widths and spacing that encode information. While 2D systems using various symbols are often called barcodes, the most common form is the parallel, linear barcode. Today, the EAN/UPC symbol, which includes UPC-A, UPC-E, EAN-13, and EAN-8 barcodes, is the standard for products scanned at retail points of sale. EAN/UPC barcodes ensure that products are correctly identified, streamline data collection, and provide more accurate data for trading partners.

The features of this reference design Atmel SAM4S_WPIR_RD kit, by Microchip Technology include image processing and decoding for barcodes and QR codes, based on Libdecodeqr and OpenCV, and it supports continuous scanning mode. The demo runs on the SAM4S-WPIR_RD Kit and is powered via a USB connector, requiring no additional controls. After successful decoding, the result is displayed on the LCD, or an error code is shown if the decoding fails. The primary clock source for the system is the internal fast RC Oscillator, defaulting to 4 MHz. The main clock source should be set to an external 12 MHz crystal to achieve maximum frequency operation, with PLLB configured as the MCK source. To configure the microcontroller with these settings, the appropriate definition must be enabled in the Board_lowlevel.c file. This configuration sets the clock at 120 MHz. 

The application includes a demo application for QR code decoding, aims to guide users in utilizing the Atmel SAM4S for this purpose. Similar to other examples for the SAM4S_WPIR_RD, this demo is provided with an IAR project and follows a similar structure. The OpenCV and Libdecodeqr libraries are included in a library format. Upon power-up, the demo displays initialization screens before starting continuous CMOS sensor acquisition. Users can place an example QR image in front of the CMOS sensor. Upon successful detection, the program processes the decode and displays the result and relevant information. The software comprises several tasks: CMOS sensor image capture, image processing, QR decoding, and LCD display.

QR codes, or Quick Response Codes, are a type of matrix barcode (or two-dimensional barcode) that have gained popularity due to their fast readability and higher storage capacity compared to standard UPC or EAN barcodes. QR codes consist of black modules arranged in a square grid on a white background. The information encoded in a QR code can be one of four standardized types of data (numeric, alphanumeric, byte/binary, and Kanji) or through supported extensions.

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Microchip Technology has tested this reference design, which includes a bill of materials (BOM), schematics, and more. Additional information about the reference design is available on the company’s website. To learn more about this reference design, click here.

Akanksha Gaur
Akanksha Gaur
Akanksha Sondhi Gaur is a journalist at EFY. She has a German patent and brings a robust blend of 7 years of industrial & academic prowess to the table. Passionate about electronics, she has penned numerous research papers showcasing her expertise and keen insight.

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