nsadash.blogg.se - 2 bit gray code counter verilog code

These codes are also known as unit-distance, single-distance, single-step, monostrophic or syncopic codes, in reference to the Hamming distance of 1 between adjacent codes.įor decimal 15 the code rolls over to decimal 0 with only one switch change.

This problem can be solved by changing only one switch at a time, so there is never any ambiguity of position, resulting in codes assigning to each of a contiguous set of integers, or to each member of a circular list, a word of symbols such that no two code words are identical and each two adjacent code words differ by exactly one symbol. If the output feeds into a sequential system, possibly via combinational logic, then the sequential system may store a false value. When the switches appear to be in position 001, the observer cannot tell if that is the "real" position 1, or a transitional state between two other positions. Even without keybounce, the transition might look like 011 - 001 - 101 - 100. In the brief period while all are changing, the switches will read some spurious position. In the transition between the two states shown above, all three switches change state. The problem with natural binary codes is that physical switches are not ideal: it is very unlikely that physical switches will change states exactly in synchrony. If that device uses natural binary codes, positions 3 and 4 are next to each other but all three bits of the binary representation differ: Many devices indicate position by closing and opening switches.

5.1 Gray codes with n bits and of length less than 2 n.

2.9.1 Gray code counters and arithmetic.

2.9 Cycling through states with minimal effort.

2.8 Communication between clock domains.

2.3 Analog-to-digital signal conversion.

Gray codes are widely used to prevent spurious output from electromechanical switches and to facilitate error correction in digital communications such as digital terrestrial television and some cable TV systems. That way, incrementing a value from 1 to 2 requires only one bit to change, instead of two. In Gray code, these values are represented as " 001" and " 011". The reflected binary code ( RBC), also known as reflected binary ( RB) or Gray code after Frank Gray, is an ordering of the binary numeral system such that two successive values differ in only one bit (binary digit).įor example, the representation of the decimal value "1" in binary would normally be " 001" and "2" would be " 010".

Ordering of binary values, used for positioning and error correction