control devices via parallel port, save state of each address?

[sc2sc1]

hello,
i am trying to control devices via parallel port, in Attachment the circuit diagram, devices will be connect to 3 flip flops.

assume that i want to switch ON the first device in the first flip flop, so the [0 - 3] data bus = 1000 and decoder input = 01 then 00 to generate puls to the flip flop.

now if i want to switch ON the second device the [0-3] data bus = 1100 and so on.

is this the correct method?
is there any more efficient design?
thanks.

 

[Mikebits]

Just make sure your data bits are valid before you output address to make clock. I also assume you will tie your enable pins and MR pins to the right logic level.

 

[ericgibbs]

hello,
i am trying to control devices via parallel port, in Attachment the circuit diagram, devices will be connect to 3 flip flops.

assume that i want to switch ON the first device in the first flip flop, so the [0 - 3] data bus = 1000 and decoder input = 01 then 00 to generate puls to the flip flop.

now if i want to switch ON the second device the [0-3] data bus = 1100 and so on.

is this the correct method?
is there any more efficient design?
thanks.

hi,
Your PC parallel pin numbers are wrong.

EDIT:
You should store an image of each of the states of the 175's in the PC memory
I would also use the Enable line on the 139.

 

[Mikebits]

Good catch. I did not even check.
https://pinouts.ru/ParallelPorts/ParallelECP_pinout.shtml

 

[sc2sc1]

Just make sure your data bits are valid before you output address to make clock. I also assume you will tie your enable pins and MR pins to the right logic level.

thank you for web site link, i will connect the pins correct

You should store an image of each of the states of the 175's in the PC memory
I would also use the Enable line on the 139.

thank you, This is what I will do

 

[ericgibbs]

thank you for web site link, i will connect the pins correct
thank you, This is what I will do

hi,
Have a look at these files, they may help.

 

[sc2sc1]

hi,
Have a look at these files, they may help.

thank you, it is so helpful