Extend your modulo 8 Gray code counter from Exercise 3.27 to be an UP/DOWN counter by adding an UP input. If UP = 1, the counter advances to the next number. If UP = 0, the counter retreats to the previous number.

Exercise 3.27:

Gray codes have a useful property in that consecutive numbers differ in only a single bit position. Table 3.23 lists a 3-bit Gray code representing the numbers 0 to 7. Design a 3-bit modulo 8 Gray code counter FSM with no inputs and three outputs. (A modulo N counter counts from 0 to N - 1, then

repeats. For example, a watch uses a modulo 60 counter for the minutes and seconds that counts from 0 to 59.) When reset, the output should be 000. On each clock edge, the output should advance to the next Gray code. After reaching 100, it should repeat with 000.