Bidirectional counters are capable of counting up or down through any given count sequence, as well as counting \"up\" from zero and increasing or increasing to some preset value, and sometimes counting \"down\" from a predetermined value to zero so that we can produce an output that is activated when a zero count or other preset value is reached.
This type of counter is commonly called a decrement counter, (CTD). In a binary or BCD decrement counter, the count is reduced by 1 for each external clock pulse from a preset value. Special dual-purpose ics, such as TTL 74LS193 or CMOS CD4510, are 4-bit binary Up or Down counters with an additional input pin to select up or down count modes.
4 bit down counter
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In the 4-bit counter above, the output of each flip-flop changes state at the falling edge (the 1 to 0 transition of the CLK input, triggered by the Q output of the previous flip-flop instead of the Q output is the same as the up counter configuration. Therefore, when the current flip-flop changes from 0 to 1 at its output instead of changing from 1, each flip-flop will change state. To 0.
backward-forward counter
Both synchronous and asynchronous counters can count \"up\" or count \"down,\" but they are another \"universal\" counter type that can count up or down depending on the state of its input control pin, these are called bidirectional counters.
A bidirectional counter, also called an up\/down counter, is capable of counting through any given count sequence in either direction, and can be reversed at any point in the count sequence by using additional control inputs as shown below.
Synchronize 3-bit up\/down counters
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The circuit above is a simple 3-bit Up\/Down synchronous counter that uses JK flip-flops configured to switch or operate a T-flip-flop with a maximum count of zero (000) to seven (111) and back to zero again. The 3-bit counter then advances up in order (0,1,2,3,4,5,6,7) or down in reverse order (7,6,5,4,3,2,1,0).
In general, most bidirectional counter chips can change their counting direction up or down at any point in their counting sequence. This is done by using an additional input pin that determines the direction of the count, up or down, and the timing diagram gives an example of a counter operation because this up\/down input changes the state.
Now, both up and down counters are integrated in a single IC that is fully programmable to count from any preset value in both the \"up\" and \"down\" directions, resulting in a complete bidirectional counter chip. The common chips available are 74HC190 4-bit BCD decimal up\/down counter, 74F569 which is a fully synchronous up\/down binary counter and CMOS 4029 4-bit synchronous up\/down counter.
A counter chip is a digital logic chip used to count and record the number of pulses of an input signal. Its use is as follows:
First, the input end of the counting device is connected to the pulse signal source that needs to be counted, usually a clock signal.
The output is then connected to the relevant display device or other logic circuit in order to display or utilize the counting results.
Before use, the initial value of the counter needs to be set to determine the counting range. When the input pulse signal arrives, the counter will automatically increase and give the corresponding counting result through the output end. Appropriate control signals can be provided when it is necessary to clear or reset the counter. In short, the counter chip is very practical and can be widely used in counting, timing and other scenarios.
A counter chip is an integrated circuit that counts and records the number of input pulses. The method of using the counter chip is as follows:
First, the input pulse is connected to the count input of the counter chip.
Then, set the initial value of the counter as needed.
Next, the clock signal is connected to the clock input of the counter chip to control the counting speed of the counter.
As the counter receives each pulse, it automatically increases the count. Finally, the count value can be obtained by reading the output of the counter. Counter chip is widely used in timing, frequency measurement, event counting and other fields.