I am trying to make a module (in a logic simulator) that is equivalent to a 4017 decade counter. The data sheet logic diagram for MC14017B (ON Semiconductor) shows 5 flip flops that show CDRQ labels. Can anyone please let me know what type of flip flops they are?
Thank you
Barrie

 

C = clock
D = data
R = reset
Q = Q output

It is a D type flip flop.

 

Many thanks for your quick reply. Can I assume that the Reset is equivalent to the Preset pin on the simulator flip flop?
There are also two more complementary inputs of C and R on the logic diagram. I am trying to match them to the simulator pins which are labeled "enable" and "clear".
Will you please confirm the following is correct.
C(bar) = enable
R(bar) = clear
Thank you
Barrie

 

Look up the data sheet for a CD4013 or a 7474 to get the full turnout of a d flip flop.

They are clocked devices, so the C input must be the clock. R is reset. The reset input always places the flip flop into the state where Q is low, and Q^ is high.

A "normal" D flip flop has an S input as well. It is the overriding SET input that forces Q high and Q^ low. The S input would be the equivalent of the simulator Preset. To get the simulation working properly, tie the Preset to a logic level that disables it.

 

Thank you again for your help and guidance. I can now start my project.

 

Have a look here:

http://www.play-hookey.com/digital/johnson_counter.html

They explain quite nicely how the Johnson counter works.

 

Wow. That is exactly what I needed. Thank you very much.