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to the NAND gate. The NAND gate outputs are connected to the CLR input of each of the FFs.". It counts from 0 to 9 and then resets to zero. The counter output can be set to zero by pulsing the reset line low. The count then increments on each clock pulse until it reaches 1001 (decimal 9). When it increments to 1010 (decimal 10), both inputs of the NAND gate go high. The result is that the NAND output goes low, and resets the counter to zero. D going low can be a CARRY OUT signal, indicating that there has been a count of ten.
712:
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counts when incrementing; zero counts when decrementing), the next clock will cause the counts to overflow or underflow, and the counting sequence will start over. Internally, counters use flip-flops to represent the current counts and to retain the counts between clocks. Depending on the type of counter, the output may be a direct representation of the counts (a binary number), or it may be encoded. Examples of the latter include ring counters and counters that output Gray codes.
247:
258:
1 flip-flop, bit 1 clocks the bit 2 flip-flop, etc.). The first flip-flop is clocked by rising edges; all other flip-flops in the chain are clocked by falling clock edges. Each flip-flop introduces a delay from clock edge to output toggle, thus causing the counter bits to change at different times and producing a ripple effect as the input clock propagates through the chain. When implemented with discrete flip-flops, ripple counters are commonly implemented with
38:
397:
913:
472:) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage. The register cycles through a sequence of bit-patterns, whose length is equal to twice the length of the shift register, continuing indefinitely. These counters find specialist applications similar to the decade counter (note: the
664:. They typically consist of a series of disks mounted on an axle, with the digits zero through nine marked on their edge. The right-most disk moves one increment with each event. Each disk except the left-most has a protrusion that moves the next disk to the left one increment after the completion of one revolution. Such counters were used as
387:
For example, the circuit shown to the right is an ascending (up-counting) four-bit synchronous counter implemented with JK flip-flops. Each bit of this counter is allowed to toggle when all of the less significant bits are at a logic high state. Upon clock rising edge, bit 1 toggles if bit 0 is logic
265:
In the simplest case, a one-bit counter consists of a single flip-flop. This counter will increment (by toggling its output) once per clock cycle and will count from zero to one before overflowing (starting over at zero). Each output state corresponds to two clock cycles; consequently, the flip-flop
257:
An asynchronous (ripple) counter is a "chain" of toggle (T) flip-flops wherein the least-significant flip-flop (bit 0) is clocked by an external signal (the counter input clock), and all other flip-flops are clocked by the output of the nearest, less significant flip-flop (e.g., bit 0 clocks the bit
412:
integrated circuit did) or other binary encodings. A decade counter is a binary counter designed to count to 1001 (decimal 9). An ordinary four-stage counter can be easily modified to a decade counter by adding a NAND gate as in the schematic to the right. Notice that FF2 and FF4 provide the inputs
151:
Some counters provide a
Terminal Count output which indicates that the next clock will cause overflow or underflow. This is commonly used to implement counter cascading (combining two or more counters to create a single, larger counter) by connecting the Terminal Count output of one counter to the
127:
circuit that has a clock input signal and a group of output signals that represent an integer "counts" value. Upon each qualified clock edge, the circuit will increment (or decrement, depending on circuit design) the counts. When the counts have reached the end of the counting sequence (maximum
366:
that require the counter to have a fast output settling time. Also, it is often impractical to use ripple counter output bits as clocks for external circuits because the ripple effect causes timing skew between the bits. Ripple counters are commonly used as general-purpose counters and clock
159:
Counters are generally classified as either synchronous or asynchronous. In synchronous counters, all flip-flops share a common clock and change state at the same time. In asynchronous counters, each flip-flop has a unique clock, and the flip-flop states change at different times.
645:
Many automation systems use PC and laptops to monitor different parameters of machines and production data. Counters may count parameters such as the number of pieces produced, the production batch number, and measurements of the amounts of material used.
361:
Ripple counters exhibit unstable output states while the input clock propagates through the circuit. The duration of this instability (the output settling time) is proportional to the number of flip-flops. This makes ripple counters unsuitable for use in
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output frequency is exactly half the frequency of the input clock. If this output is then used as the clock signal for a second flip-flop, the pair of flip-flops will form a two-bit ripple counter with the following state sequence:
438:) with the output of the last one connected to the input of the first, that is, in a ring. Typically, a pattern consisting of a single bit is circulated, so the state repeats every n clock cycles if n flip-flops are used.
383:
In a synchronous counter, the clock inputs of the flip-flops are connected, and the common clock simultaneously triggers all flip-flops. Consequently, all of the flip-flops change state at the same time (in parallel).
155:
The modulus of a counter is the number of states in its count sequence. The maximum possible modulus is determined by the number of flip-flops. For example, a four-bit counter can have a modulus of up to 16 (2^4).
699:
357:
Additional flip-flops may be added to the chain to form counters of any arbitrary word size, with the output frequency of each bit equal to exactly half the frequency of the nearest, less significant bit.
676:, in production machinery as well as in other machinery. One of the largest manufacturers was the Veeder-Root company, and their name was often used for this type of counter.
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A ring counter is a circular shift register that is initiated such that only one of its flip-flops is the state one while others are in their zero states.
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Mechanical counter wheels showing both sides. The bump on the wheel displayed at the top engages the ratchet on the wheel below every turn.
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This article is about the term counter used in electronics, computing, and mechanical counting devices. For other uses, see
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Voltage changes on the five outputs of the binary counter counting from 00000, left to 11111 (or 31), right (vertically).
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A decade counter counts in decimal digits, rather than binary. A decade counter may have each (that is, it may count in
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The following machines are listed in order of power, with each one being strictly more powerful than the one below it:
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a
Johnson counter), digital-to-analog conversion, etc. They can be implemented easily using D- or JK-type flip-flops.
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Many counters provide additional input signals to facilitate dynamic control of the counting sequence, such as:
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has received. Once set up, these counters will be incremented by one every time the web page is accessed in a
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262:, with each flip-flop configured to toggle when clocked (i.e., J and K are both connected to logic high).
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Long before electronics became common, mechanical devices were used to count events. These are known as
180:– counts up and down, as directed by a control input, or by the use of separate "up" and "down" clocks.
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was popular in the mid to late 1990s and early 2000s, later replaced by more detailed and complete
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high; bit 2 toggles if bits 0 and 1 are both high; bit 3 toggles if bits 2, 1, and 0 are all high.
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frequency dividers in applications where the instantaneous count and timing skew is unimportant.
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Reset – sets counts to zero. Some IC manufacturers name it "clear" or "master reset (MR)".
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510:) and can be arbitrarily long. A counter is usually considered in conjunction with a
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and multiple output lines. The values on the output lines represent a number in the
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is a device which stores (and sometimes displays) the number of times a particular
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is a computer program that indicates the number of visitors or hits a particular
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Decrement the counter by one (if it's already zero, this leaves it unchanged).
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559:. They have the same power. The first two and the last one are levels of the
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The first machine, an FSM plus two counters, is equivalent in power to a
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are used mainly for stocktaking and counting people attending events.
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Counters are implemented in a variety of ways, including as dedicated
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Data – parallel input data which represents a particular counts value.
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connected in a cascade. Counters are a very widely used component in
50:
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514:(FSM), which can perform the following operations on the counter:
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Direction – determines whether counts will increment or decrement.
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Decade counter – modulus ten counter (counts through ten states).
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912:
813:
Digital
Principles Foundation of Circuit Design and Application
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For the first and last, it doesn't matter whether the FSM is a
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Modulus counter – counts through a particular number of states.
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and also incorporated as parts of larger integrated circuits.
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Device storing number of times an event or process occurred
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is considered a type of memory. A counter stores a single
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Deterministic or non-deterministic FSM plus two counters
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Early IBM tabulating machine using mechanical counters.
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A circuit decade counter using JK Flip-flops (74LS112D)
163:
Counters are categorized in various ways. For example:
226:, as general-purpose counter and timer peripherals in
623:, or styles; the classic example is the wheels of an
200:
Gray-code counter – outputs a sequence of Gray codes.
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number system. Each pulse applied to the clock input
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Design and
Synthesis of a MOD 13 Binary Down Counter
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A counter circuit is usually constructed of several
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147:Load – copies parallel input data to the counts.
379:A 4-bit synchronous counter using JK flip-flops
203:Shift register generator counter – based on a
693:that pioneered the data processing industry.
607:The number is usually displayed as an inline
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483:
689:counters were used to accumulate totals in
924:Assim, Ara Abdulsatar Assim (2021-10-19).
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619:. Images may be presented in a variety of
65:has occurred, often in relationship to a
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837:Horowitz, Paul; Hill, Winfield (1989).
547:Deterministic or non-deterministic FSM.
76:circuit with an input line called the
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541:Non-deterministic FSM plus one counter
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250:Asynchronous counter created from two
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138:Enable – allows or inhibits counting.
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615:or on a physical counter such as a
107:, and are manufactured as separate
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544:Deterministic FSM plus one counter
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152:Enable input of the next counter.
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557:nondeterministic finite automaton
518:Check whether the counter is zero
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867:Modern Dictionary of Electronics
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535:Non-deterministic FSM plus one
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843:. Cambridge University Press.
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553:deterministic finite automaton
222:, as embedded counters within
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1:
934:10.36227/techrxiv.16810198.v1
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668:for bicycles and cars and in
521:Increment the counter by one.
242:Asynchronous (ripple) counter
69:. The most common type is a
717:Several mechanical counters.
205:shift register with feedback
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96:the number in the counter.
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810:Singh, Arun Kumar (2006).
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741:Time to digital converter
484:Computer science counters
434:(a cascade connection of
186:– formed by a "circular"
458:switch-tail ring counter
32:Counter (disambiguation)
864:Graf, Rudolf F (1999).
641:Computer based counters
840:The Art of Electronics
816:. New Age Publishers.
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254:
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790:Integrated Publishing
570:. See the article on
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249:
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920:at Wikimedia Commons
761:Asynchronous circuit
512:finite-state machine
496:computability theory
466:walking ring counter
462:twisted ring counter
430:A ring counter is a
406:binary-coded decimal
364:synchronous circuits
193:Johnson counter – a
766:Synchronous circuit
691:tabulating machines
650:Mechanical counters
371:Synchronous counter
220:integrated circuits
115:Electronic counters
109:integrated circuits
656:Mechanical counter
617:mechanical counter
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916:Media related to
687:Electromechanical
561:Chomsky hierarchy
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961:Unary operations
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786:"Decade Counter"
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572:counter machines
490:Register machine
281:(Q1:Q0) decimal
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228:microcontrollers
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756:Prayer beads
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635:web traffic
631:Web counter
602:web browser
594:hit counter
590:web counter
584:Web counter
578:Web counter
506:(initially
272:Clock cycle
945:Categories
928:(Report).
893:VR History
870:. Newnes.
772:References
637:measures.
613:plain text
436:flip-flops
121:electronic
101:flip-flops
94:decrements
90:increments
71:sequential
679:Handheld
666:odometers
408:, as the
232:IP blocks
230:, and as
51:computing
896:, Veeder
735:See also
625:odometer
598:webpage
500:counter
474:74x4017
195:twisted
63:process
55:counter
874:
847:
820:
795:19 Mar
611:or in
82:binary
621:fonts
555:or a
537:stack
468:, or
236:FPGAs
224:ASICs
78:clock
67:clock
59:event
872:ISBN
845:ISBN
818:ISBN
797:2020
508:zero
498:, a
456:(or
410:7490
215:and
53:, a
49:and
930:doi
592:or
494:In
234:in
217:LSI
213:MSI
119:An
92:or
86:BCD
84:or
61:or
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627:.
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588:A
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