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Digital Basics Tutorial.
Tri-state buffer logic discussion
Verilog RTL example for tri-state logic buffer. Also discussed below are the output results.
Tri-state buffer test-bench.
Tristate buffer, inverting tristate buffer symbol, truth table and on chip implementations bus, bidirectional IO port direction control.

// Tristate Buffer

module tristate_buffer(input_x, enable, output_x);

input input_x;

input enable;

output output_x;

assign output_x = enable? input_x : 'bz;



Output of above Tri-State Buffer code


input_x = 0, enable = 0, output_x = z

input_x = 1, enable = 0, output_x = z

input_x = 1, enable = 1, output_x = 1

input_x = 0, enable = 1, output_x = 0

Adder tb.

Tri-state buffer acts as a switch in digital circuit by isolating a signal path in a circuit. This switch can attain three logical states. The three states are 0, 1 and ‘Z’. The logical state 0 and 1 are possible when the switch is CLOSE. The logical value ‘Z’ or high impedance is attained when switch is OPEN. So when switch is open the input to tristate buffer is isolated from the circuit and output can be driven by some other logical path on a shared connection/bus.  

We will discuss tri-state logic with brief introduction followed by Verilog code to implement it at RTL level. Will also cover Inverting tristate buffer

Tristate Inv Tristate Bus
Interview Questions. Main, FPGA, Digital basics
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