8 bit Shift Register

Gerardo's picture

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Joined: Mar 09, 2020

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8 bit Shift Register
March 9, 2020 - 4:38am

Hi! I'm a student of Electric Engineering and I got a problem on a Electronic project. I have to make an 8-bit shift register with serial input and serial output. The basics of the project is that it has to have two push buttons: one will be a logic 1 and the other a logic 0. The shift register has to somehow show the 'move' of the register to see that it works, so I planned on using 8 LEDs that will work like this: when I press button 1, it has to turn on a LED and when I press 0, the LED has to turn off. If I make a secuence, for example, 01100101, being the first 0 the last bit I pressed and the last 1 the first bit, the LED configuration shall be the same: Off - On - On - Off - Off - On - Off - On. The hard or difficult part of the project is that I'm not allowed to use any type of IC nor Digital Electronic, just transistors and pasive components. I attach my previous design, there can be seen the configuration of the two pulses and two masters slaves but the connection of the rest of the masters slaves was the same, it didn't work as I thought it will be, LEDs automatically turn on (except the first one) when I start simulating or when I connect the circuit in protoboard. I was trying to use a Master-Slave configuration to make it work, the clock and input D I assumed that should be separated, that's why I put a relay to separate them. The logic 1 I made it by energizing input and clock with the same pulse, while the logic 0 I made it by just enegizing the clock. I was using 2N2222A transistors in that task in NAND and NOT configurations. If you could help me or give some ideas I would really appreciate. Thank you!

jaksonlee's picture

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Joined: Nov 07, 2019

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8-bit shift register is a
March 9, 2020 - 10:25am

8-bit shift register is a convenient way to map a serial stream of signals to parallel output. But what exactly does this mean, and when is it useful? We will try to answer these questions below, as well as give you an example application of where the shift register came in handy. 

The shift register requires a minimum of three stamp pins to operate. One pin is used as input, one for a clock signal, and one for a clear signal. All operations happen on the leading edge of the clock signal. Values are passed down the line of outputs with each cycle of the clock... This will hopefully become clearer with the following diagrams.

Both the input and clear signals can be wired directly to stamp pins. Setting the the clear pin to low will cause all the outputs of the shift register to be low. Setting the clear pin to high enables you to change the values on the output puts using the clock signal and input as described later on.
marry roser's picture

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Joined: Nov 21, 2019

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A simpleĀ 8-bit shift register
March 9, 2020 - 11:05am

A simple 8-bit shift register IC. Simply put, this shift register is a device that allows additional inputs or outputs to be added to a microcontroller by converting data between parallel and serial formats. Essentially it takes 8 bits from the serial input and then outputs them to 8 pins.

Using this 8-bit shift register is a convenient way to map a serial stream of signals to parallel output. But what exactly does this mean, and when is it useful? We will try to answer these questions below, as well as give you an example application of where the shift register came in handy.

How it Works

The shift register requires a minimum of three stamp pins to operate. One pin is used as input, one for a clock signal, and one for a clear signal. All operations happen on the leading edge of the clock signal. Values are passed down the line of outputs with each cycle of the clock... This will hopefully become clearer with the following diagrams.

Both the input and clear signals can be wired directly to stamp pins. Setting the the clear pin to low will cause all the outputs of the shift register to be low. Setting the clear pin to high enables you to change the values on the output puts using the clock signal and input as described later on.