Counters 91509 L 27 Counters Copyright 2009 Joanne

Class 27 – Counters o A counter we have seen A ripple counter Other

Ripple Counter o o o “A register that goes through a prescribed sequence of

A ripple counter o Made out of T type FFs Using D FFs o

Synchronous counters o Desire to move through the sequence of binary numbers, either counting

up binary counter with ENable o o Synchronous Up counter with count enable Symbol

Binary counter with || load o Now add parallel load capability 9/15/09 - L

Up/Down counters o o o To count up the input to the next state

BCD counter o Not how it goes back to 0 after 9 (1001) is

Arbitrary count sequences o A counter can be designed to count in any sequence.

One last topic o o ONE HOT – what summer days sometimes are But

Class 27 assignment o o Covered counters from section 7 -6 Problems for hand

Slides: 12

Download presentation

Ripple Counter o o o “A register that goes through a prescribed sequence of distinct states upon the application of a sequence of input pulses is called a counter. ” The input pulses could be the clock or some other input that occurs when the next step in the count should occur. A counter that follows the binary number sequence is called a binary counter. 9/15/09 - L 27 Counters Copyright 2009 - Joanne De. Groat, ECE, OSU 3

Synchronous counters o Desire to move through the sequence of binary numbers, either counting up or down, such that all the outputs achieve their new value at about the same time on either the rising or falling edge of the clock signal. 9/15/09 - L 27 Counters Copyright 2009 - Joanne De. Groat, ECE, OSU 5

Up/Down counters o o o To count up the input to the next state is obtained by adding 1 to the current state. The count down the input to the next state is obtained by subtracting 1 from the current state. An up/down counter with enable has the following feedback equations: 9/15/09 - L 27 Counters Copyright 2009 - Joanne De. Groat, ECE, OSU 8

One last topic o o ONE HOT – what summer days sometimes are But in state machines it is a design style where 1 F/F is used for each state. A ‘ 1’ will progress from FF to FF with all others being ‘ 0’. 9/15/09 - L 27 Counters Copyright 2009 - Joanne De. Groat, ECE, OSU 11

Class 27 assignment o o Covered counters from section 7 -6 Problems for hand in n o Problems for practice n o Nothing new Reading for next class: 7 -6 9/15/09 - L 27 Counters Copyright 2009 - Joanne De. Groat, ECE, OSU 12