What Is a Shift Register?
In a digital circuit, a shift register is a flip-flop-based device that operates under several identical time pulses. Data is input to the device in parallel or serially, and then each time pulse is turned left or Shift right one bit to output at the output. This type of shift register is one-dimensional. In fact, there are also multi-dimensional shift registers, that is, the input and output data itself are some columns. A method for implementing such a multi-dimensional shift register may be to connect several shift registers with the same number of bits in parallel.
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- The shift register can not only register data, but also can sequentially shift the data in it to the left or right under the effect of the clock signal.
- The schematic of the four-bit shift register is shown in the figure. FF0, FF1, FF2, and FF3 are four edge-triggered D flip-flops, and the output terminal Q of each flip-flop is connected to the input terminal D of a flip-flop on the right. Because there is a delay time from the rising edge of the clock signal CP to the flip-flop until the new state of the output is stably established, when the clock signal is simultaneously applied to four flip-flops, each flip-flop receives The original data in the left trigger (input data D1 received by FF0). The data in the register is shifted one bit to the right in turn.
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- Commonly used integrated shifts
- According to the shift direction, it is often divided into three types: left shift register, right shift register, and bidirectional shift register;
- According to the input-output method of the shift data, it can be further divided into four circuit structures: serial input-serial output, serial input-parallel output, parallel input-serial output, and parallel input-parallel output.
- In addition, some shift registers also have a preset number function, which can put data into the registers in parallel.
- The shift register can be used for data calculation and data processing to realize serial-parallel conversion of data. It can also be connected to various shift register counters, such as ring counters and twisted ring counters.