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I am looking to start a new electronic project. For this project i will be learning to code a 7 segment 4 digit display, however i am not sure what chip to use or how to approach the start of this project. Does anyone know what chip i could use?

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  • \$\begingroup\$ That's a bit broad, also in reality most projects today wouldn't use a specific chip, they'd either drive a multiplexed 7-segment display directly from an MCU with maybe a transistor on the digit-select lines, or use a character or graphic LCD or OLED. \$\endgroup\$ Commented Mar 7, 2019 at 18:07

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MAX7219 for 4-digit, 7 segment display. Common cathode if you can for easier programming. ~ $3 from taydaelectronics.com

Max7219 will take care of the multiplexing, you send data to its registers, one for each digit.

Or, use a shift register like TPIC6C595 to sink current thru a common anode and 4 PNP transistors to source current to one digit at a time.

Or, use a shift register like MIC5891 to source current to a common cathode display and 4 NPN transistors to sink current from one digit at a time.

How deep in the weeds do you want to go?

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  • \$\begingroup\$ Yes... but a MAX7219 all by itself not on a board and without any 7-segment LEDs costs more than an I2C OLED or 4-bit character LCD display. So one would really need to want such a solution specifically. \$\endgroup\$ Commented Mar 7, 2019 at 21:35
  • \$\begingroup\$ Depends on how much time is needed to program for the displays too. With Max7219, you write to a few control registers to set it up, then you write to 4 data resisters to display numbers. Dirt simple to learn. Did you have particular I2C OLED or character LCD display in mind for comparison? No e-bay stuff, I won't buy electronics there. \$\endgroup\$ Commented Mar 7, 2019 at 21:57
  • \$\begingroup\$ Character LCDs are pretty simple and there are open source libraries. Even graphic OLEDs with their complexity take less time to hook up (once) when that is encapsulated by a library than making a board would; those can burn 512-1024 bytes of RAM, though generating a single font size of text a scan line at a time directly into the I2C would be a fun hack someone has probably already done. But if someone really wants LEDs, they are of course an option. \$\endgroup\$ Commented Mar 8, 2019 at 1:18
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The first thing is know what kind of display you have, there are two types, Common Cathode and Common Anode.

enter image description here
Source: https://www.jameco.com/jameco/workshop/techtip/working-with-seven-segment-displays.html

The displays can be driven directly by a microprocessor (if the current that the LEDS have does not exceed the microprocessor output pin current).

enter image description here

Source: http://www.electronicwings.com/avr-atmega/7-segment-display-interfacing-with-atmega16-32

Or a 7 segment LED drive can be used to drive the display (these can be found on breakout boards or at a supplier like digikey):

enter image description here

Source: http://www.electronicwings.com/avr-atmega/7-segment-display-interfacing-with-atmega16-32

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  • \$\begingroup\$ When was the last time you saw a 7446 for sale? \$\endgroup\$ Commented Mar 7, 2019 at 18:13
  • \$\begingroup\$ Not for a while, I should add or eqivalent \$\endgroup\$ Commented Mar 7, 2019 at 18:35

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