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  • PIC16F1847 Based 8x40 LED Matrix Display

  • Created: Feb 07, 2017

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LED matrix displays are often used for displaying different information. It can be text, graphics, simple animations, etc. They are usually used at gas stations displaying prices, in airport displaying flight details or directions, or in public places displaying ads. In this reference design, the circuit shows how an LED matrix display is interfaced to a microcontroller and how a single microcontroller scrolls a text message on multiple 8x8 square LED display modules.

This reference design features an 8x40 LED matrix display that scrolls a text message that it receives from a PC through a USB-to-UART converter. The circuit is mainly composed of a PIC16F1847 microcontroller, five NFM-12883AS 8x8 LED display modules, five CD74HC595E shift registers, and a ULN2803A NPN Darlington array. The center of this project is the PIC16F1847 microcontroller. The PIC16F1847 microcontroller receives the data from the PC’s serial port through its USB-UART interface and displays it to the 8x40 LED matrix display. The 8x40 LED matrix display is made by connecting and arranging five NFM-12883AS 8x8 LED display modules in a linear fashion. Since the PIC16F1847 microcontroller doesn’t have enough pins to control five display modules, five CD74HC595E shift registers were cascaded to drive the 40 columns of the LED matrix display. The PIC16F1847 microcontroller sends the data serially to the shift registers and the shift registers drive the LED display modules in parallel.

The NFM-12883AS 8x8 LED display module is a common-row-cathode type, which means that all of the LEDs’ cathodes in each individual row are interconnected. The LED matrix display has eight row pins that sink current from eight LEDs per row. Since the PIC16F1847 microcontroller cannot sink large current, an ULN2803 IC, which consists eight Darlington transistors are used to sink the current from the LED matrix display row pins. The whole circuit runs on a 5V power supply. This PIC16F1847 based 8x40 LED matrix display can be used to scroll text messages.