Beginner Concepts: 595 shift register simulator

[Aaron] just finished building an online 595 shift register simulator. These inexpensive chips let you extend the number of devices that can be controlled by a single microcontroller. You see them in quite a few LED multiplexing projects, included the Ping Pong Clock that we recently built. But they can be a bit tricky to fully grasp if you’re not familiar with the hardware.

This simulator gives you a point-and-click interface for the five possible control lines on a 595 shift register. There are three pins that must be manipulated to use the device; the serial in, clock, and latch pins. The other two are for clearing the register, and enabling output and can be considered optional. You can choose to control these with a microcontroller in your own projects for more flexibility, but often they are tied to either VCC or GND (depending on the chip) when these features are unnecessary. Give this simulator a try and then take what you learned over to a solderless breadboard and see if you can write some firmware to produce the same results. If you’re still having trouble you can take a look at this 595 tutorial for further information.

Comments

  1. Very nice. Just learned something!

  2. CalcProgrammer1 says:

    Awesome, the 74HC595’s are very nice and inexpensive chips for microcontroller projects. They’re easy to use and can control many devices from only 3-4 pins. With a standard ATMega168 at 20MHz I was able to get software-PWM out of 3 595’s chained together to drive 8 RGB LED’s. It took pretty much every bit of power the chip had but it was decent PWM. I also use 595’s when connecting parallel LCD’s to save a few pins.

  3. JimSocks says:

    Love it!

  4. acomputerdog says:

    omg i now i finally get how shift registers work!

  5. walt says:

    this is great!

  6. Ford says:

    I love this. There should be more interactive tutorials like this! Actually, I just remembered that there’s a site that has all sorts of logic tutorials like this: play-hookey.com.

    Is there a standard way to use several 595 chips to drive a multi-digit seven segment display (e.g., common cathode)? I would guess the /OE pin would come into play there. Or maybe when using 595s it’s just better to have separate digits…

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