Tag Archives: MAX7219


New version of MAX7219 based 4-digit serial seven segment LED display

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This (SPI7SEGDISP4.40-1R) is a revised version of the previous SPI seven segment LED display (4 digit) board that displayed numerals and decimal points. The new version has a better quality seven segment LED display (LTC-4727JS) with three extra LED segments, as shown below. The additional colon segments are useful in projects where you need to display time (HH:MM or MM:SS).

Newer version of 4-digit SPI seven segment LED display

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Netduino Day 4 : Eight Digit Seven Segment LED Display with MAX7219

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In Day 3 tutorial, we learnt basics of seven segment LED displays and discussed about a time-division multiplexing technique that reduces the number of required microcontroller I/O pins to drive multiple seven segment LED displays. Today we will move a step further and discuss about a serial interface (SPI) for driving 8 seven segment LED displays. The technique uses MAXIM’s MAX7219 LED driver chip that allows you to control 8 (or more in cascade configuration) common-cathode seven segment LED displays with only 3 I/O pins of Netduino. For illustrative purpose, we will use our 8-digit serial seven segment LED (8DSSSLED) display module here. The benefit of using MAX7219 is, it will do all the hard work of multiplexing operation and let the microcontroller do more important jobs. It supports SPI serial communication protocol.

Netduino controlling 8 Digit Serial Seven Segments LED using MAX7219

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Soldering the SPI7SEGDISP8.56 serial 8-digit seven segment LED display kit

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SPI7SEGDISP8.56 is a MAX7219 based serial 8-digit seven segment LED display module. With this display module, you can easily add 8 digits of seven segment LED displays to your project using only 3 I/O pins, and provides full control of all the digit segments including decimal points. You can even cascade two or more of these modules together without sacrificing any extra I/O pin. You can buy SPI7SEGDISP8.56 display kit on Tindie for only $12.00. SPI7SEGDISP8.56 PCB is double layer. The top layer consists of two 4-digit CC LED display modules (Disp1 and Disp2) arranged in a row and header connectors (JP1 and JP2), whereas the bottom layer is one where the MAX7219 chip and other passive components reside.

Assembled SPI7SEGDISP8.56 board top and bottom view

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Introducing a new serial (SPI) 8-digit seven segment LED display module using MAX7219

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Seven segment LED displays are brighter, more attractive and provide a far viewing distance as well as a wider viewing angle as compared to LCD displays. The major drawback of using seven segment LEDs is they are resource-hungry. Time-division multiplexing is the most common technique of interfacing 7-segment LEDs to microcontrollers. With this technique, an 8-digit seven segment LED display with the decimal point requires at list 16 I/O pins of the microcontroller, which is quite a lot. Consequently, their use with low pin-count microcontrollers (such as PIC12F series) is not practically feasible. Here’s our latest version of the MAX7219 based serial seven segment LED display module (SPI7SEGDISP8.56) that will allow you to add 8 digits of seven segment LED displays to your project using only 3 I/O pins, and provides full control of all the digit segments including decimal points. You can even cascade two or more of these modules together without sacrificing any extra I/O pin. SPI7SEGDISP8.56 display kit is also available for purchase on Tindie for $12.99.

SPI7SEGDISP8.56: 8-digit serial seven segment LED display

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More SPI 4-digit seven segment LED displays are available

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Four digit SPI 7-segment LED displays are back in stock now on Tindie. The board has been revised from its earlier version and now contains an additional header connector to cascade multiple displays. The new header provides access to DOUT pin of MAX7219 driver IC. If you want to add a seven segment LED display to your project without giving up too many I/O resources, this board allows you to do that using only 3 I/O pins and it costs only $10.

Assembled board

SPI 7-segment LED display kit is only $10

Tindie buying link for SPI 4-digit seven segment LED display

 

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