A counter used in digital circuits. A johnson counter is made by passing the serial output of a shift register through an inverter buffer (a "NOT" gate) and then into the serial input of the shift register. Produces a count response like this:

00000000
10000000
11000000
11100000
11110000
11111000
11111100
11111110
11111111
01111111
00111111
00011111
00001111
00000111
00000011
00000001
00000000
and so on.