Tag Archives: 74hc595

Using Shift Registers with AVR Micro – AVR Tutorial

Today I am going to explain a helpful technique used while designing embedded system. The technique is to expand the number of input and output lines available in any microcontroller. The idea is to use a shift register, a shift register help us load data in a serial fashion (requiring less number of i/o lines) and then convert the data into a parallel form that can drive many types of load like LED,Relays, motor etc, just like normal i/o ports of MCU. Their are two advantage of this method:- Only three i/o lines can drive virtually any number of output ports. Say if you want to control 50 leds that are at the distance of 2 meter from the controller then you save lots of wires! and mess up too! The above described what we called an output shift register. Another type is an input shift register. This type is used to take input. It does reverse of the output shift register. It takes parallel input and transfer it serially to the MCU. The most common commercial example I found is the NES joystick. Their are 8 buttons (you will notice 10 but 2 of it are turbo, that means they repeat action A or B(turbo A or B pressed) at particular frequency when kept depressed) The designers didn’t ran […]