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Flip-Flop Macros
Published in Murat Uzam, PIC16F1847 Microcontroller-Based Programmable Logic Controller, 2020
Example 4.21 explains the implementation of an 8-bit ring counter by using the PIC16F1847-Based PLC. A ring counter is basically a circulating shift register in which the output of the most significant stage is fed back to the input of the least significant stage. The logic diagram of the 8-bit ring counter designed by using rising edge–triggered D flip-flops is shown in Figure 4.104. When CLR signal is LOW, the output of each stage is shifted into the next stage on the positive-going edge (rising edge) of a clock pulse. If the CLR signal is HIGH, all flip-flops are reset to 0 except for the first flip-flop FF0. If the PRE signal is HIGH, the first flip-flop FF0 is preset to 1. Different bit patterns can be initially loaded into the counter by using the PRE, CLR, and CP inputs. Table 4.43 shows the truth table for the 8-bit ring counter shown in Figure 4.104, assuming that initially, data Q0Q1Q2Q3Q4Q5Q6Q7 = 10000000 is stored in the register. Likewise, Table 4.44 shows the truth table for the 8-bit ring counter shown in Figure 4.104, assuming that initially, data Q0Q1Q2Q3Q4Q5Q6Q7 = 11100000 is stored in the register.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
generates a sequence in which a 1 moves from one position to the next position in the output pattern. For example, the outputs of a 5-bit ring counter follow the sequence: 10000,01000,00100,00010,00001, 10000,…. A Johnson counter or twisted ring counter is a ring counter whose final output is “twisted” before being fed back to the first stage, so that when the final output is a 1 the next value of the first output is a 0, and when the final output is a 0 the next value of the first output is a 1. The sequence for a 5 -bit Johnson counter is 10000,11000,11100,11110,11111,01111,00111,00011,00001,10000,…. Johnson counters have the characteristic that only one digit changes from one number in the sequence to the next number. This characteristic is particularly convenient in eliminating logic glitches that can occur in logic circuits using counter outputs. Logic glitches are unwanted logic pulses of very short duration.
Digital communication systems
Published in Geoff Lewis, Communications Technology Handbook, 2013
Ring counters. A ring counter is formed by taking the output from the last flip-flop and feeding it into the input of the first. Such a construction is often referred to as a circulating memory because if all cells except one are set to 0 (the exception is thus set to 1), on a series of clock pulses the 1 will circulate around the chain. For an N-stage counter, the 1 will complete one cycle every N pulses. As a counter, the count is taken by noting which cell is set to 1.
Synthesis of programmable biological central processing system
Published in Journal of the Chinese Institute of Engineers, 2021
Wei-Xian Li, Jiangfeng Cheng, Chun-Liang Lin, Chia-Feng Juang
A biological ring counter determines the Bio-CPU’s working sequence, which provides three consecutive signal sequences corresponding to three distinct operations in a consecutive loop. A ring counter connects the output of the last shift register to the input of the first shift register and circulates a single bit with a value of one around the ring.