Having a User Input and Default Mode

A project log for Shift Register/Attiny85 Business Sign

Making a sign to catch customers attention to a survey promotion.

Alvi AhmedAlvi Ahmed 07/16/2017 at 21:100 Comments

Since I ditched the idea of using an AVR to control leds, I opted to just use a 555 timer to control the clock and latch pins of the shift register and just have the user put in their own patterns via a push button wired up to the data pin.

To have the pattern constantly repeating, I added an AND gate to the whole circuit. One of the AND gate inputs is wired to high, the other input wired to the last led and the output wired back to data.

Thus repeating any pattern the user decides to input into the shift register. Since 1 and 0 is 0, and 1 and 1 is one, therefore any bit on the last led will be copied and the value will be sent back to the first serial pin.

The clear pin is also wired to a push button, so that the user can clear the register whenever they want.   

There is also a potentiometer wired to the clock and latch timer, to give the user the ability to control the speed of the patterns.

Off course since this is meant for a business, there may not be enough time for the user to input there own pattern, therefore I added a default setting. I added another 555 timer at a fixed frequency and wired it to the serial pin, therefore adding bits to the shift register at a constant frequency, which will also be able to be repeated as well. 

The user has the option to be able to switch between user input mode and default mode, via a toggle switch. 

The whole circuit is powered by 2 AA batteries. 

For this picture, ignore the transistor since that was a failed attempt in to accomplish something else. The empty ic socket is supposed to be for the AND gate