The 74HC165 chip can be obtained very inexpensively (under $0.50) and it's available from a number of different online retailers. The 74HC165 chip is a parallel-load, serial out register chip. The real use of it, though, would be parallel-to-serial conversion. Whenever the LED at Q H is on, the LED at Q H is off.Īnd whenever the LED at Q H is off, the LED at Q H is on.Įven though this is not the real purpose of the circuit, it simply shows to demonstrates how the register works. Q H is the opposite logic state from each output of Q H. It's not in the order from A to H, as you might think, but it's from

This is in contrast to a parallel shift register, in which all 8 bits are shifted in at the same time. It is a serial shift register, so each bit is shifted in 1 bit at a time until all the bits are shifted in. We just simply show how a parallel-load, serial-out register works, which is what the 74HC165 chip is. However, we won't build this type of circuit here. Pretty much instaneously if you have a fast clock signal to the serial-in, parallel-out chip. Thus, you can shift data in parallel and see the result parallel If you connect the serial data output of a 74HC165 to a serial load, parallel output chip such as aħ4HC595, you can have a parallel-in, parallel-out register. Parallel loading, in ways, can be viewed as simpler, because you can shift all the data in at one time. So, in recap, it shifts in all data at one time and shifts the data out one a time.

So the 74HC165 allows parallel loading on the input side and on the output side shifts bits out serially, meaning Loading allows us to input all 8 bits together during one clock cycle, while serial loading only allows 1 bit to be shifted This is contrast to serial loading, in which only one bit can be shifted in at a time. Parallel-loading means that all the 8 bits can be loadedĪll together at one time. The 74HC165 register is a parallel-load, serial-out register. In this project, we will build a register circuit using a 74HC165 chip.

How to Build a Register Circuit with a 74HC165 Chip

74hc165 avr studio