# 79 Asynchronous 3-Bit Down Counter

## 79 : Asynchronous 3-Bit Down Counter

### How it works

See The Wokwi gate and simulation.

• The sequence in which the counter works is as follows : 7: 0111 3: 0011 5: 0101 1: 0001 6: 0110 2: 0010 4: 0100 0: 0000 Here’s how the counter works : first, all the three flip flops are set to 1 then for changing the inputs i have used the switch 1 of the Dip switch.
• When the count signal is triggered, the first flip-flop (least significant bit) toggles from 1 to 0, which produces the binary number 0111 (decimal 7).
• The second count signal should not trigger a change in the counter value, as the next count is 3, not 6.
• The third count signal triggers a change in the counter value, where the second flip-flop toggles from 1 to 0, which produces the binary number 0101 (decimal 5).
• The fourth count signal should not trigger a change in the counter value, as the next count is 1, not 4.
• The fifth count signal triggers a change in the counter value, where the first flip-flop toggles from 0 to 1, and the third flip-flop toggles from 0 to 1, which produces the binary number 0110 (decimal 6).
• The sixth count signal should not trigger a change in the counter value, as the next count is 2, not 5.
• The seventh count signal triggers a change in the counter value, where the second flip-flop toggles from 0 to 1, which produces the binary number 0100 (decimal 4).
• The eighth count signal triggers a change in the counter value, where all three flip-flops toggle from 0 to 1, which produces the binary number 0000 (decimal 0).
• The counter stays at 000 until the count signal is triggered again, which causes all three flip-flops to be set back to 1, and the counting process starts again from the beginning of the sequence. In summary, the 3-bit asynchronous down counter counts down in the sequence 7, 3, 5, 1, 6, 2, 4, 0 using three flip-flops and asynchronous inputs to trigger each flip-flop in the sequence.

### How to test

For Testing this project, the user has to use the switch 1 of the dip switch to give different inputs and then get the desired output on the 7-segment display.

### IO

# Input Output
0 clock segment a - OUT0
1 reset segment b - OUT1
2 I0 - Input segment c - OUT2
3 I1 - None segment d - OUT3
4 I2 - None segment e - OUT4
5 I3 - None segment f - OUT5
6 I4 - None segment g - OUT6
7 Unused dot - None