Serial to parallel conversion

Hello friends ,
i am using 74165 to convert parallel to serial , then 74164 to convert serial data into parallel which finally goes into a seven segment display.

In first case (parallel to serial ) ,i am simply giving 5V to 4 pins and 0V to other 4pins (i.e. 10101010 input ) .

But the problem is that i am not getting the output at seven segment.

Can some one please post some circuit similar to this .
or please give some link where i can read about it.
(datasheets are rather misleading)

Thanks !

truebs said:

please give some link where i can read about it.
(datasheets are rather misleading)

Click to expand...

SERIAL TO PARALLEL OUTPUT FROM THE PIC USING 74164
http://www.drzyzgula.org/bob/text/fr.tom/ser-par.txt

PARALLEL TO SERIAL INPUT TO A PIC USING A 74165
http://www.drzyzgula.org/bob/text/fr.tom/shift.txt

Thanks for that link ,it was quite helpful.

But m still not clear about :

Asynchrounous load /shift pin of 74165 ., what is its use ?
should i tie it to high or low ?

Also can i connect both 74165 and 74164 directly ,with same clock applied to both ?
thanks !

truebs said:

Asynchrounous load /shift pin of 74165 ., what is its use ?
should i tie it to high or low ?

Click to expand...

As long as pin 1 (load /shift) is tied to "L", the pulses aplied to clock input (pins 2 or 15) has no effects on the output Q7.
The chip is in Parallel Mode entry and data aplied on inputs is loaded into internal RS flip-flops.
This load procedure is asynchrounous. You don't need a pulse aplied on clock input to load the data.
That's it, as long as pin 1 is tied to "L" you can change the data as many times you wish.
When you're ready, bring the load/shift pin to "H" (be sure that data inputs are stable minimum 10ns before the pin going high).
Now if the clock input is "H" you must bringing down "L" and then "H" in order to see the first bit coming out to Q7 output.
Remember the circuit shifts on the rising edge of clock signal.

truebs said:

Also can i connect both 74165 and 74164 directly ,with same clock applied to both ?
thanks !

Click to expand...

YES, you can do that but, bear in mind that both circuits works on rising edge of clock signal.
In order to avoid the delays effect on the line between two circuits and meeting the setup and hold time requirements for 74164 it would be wise to send the clock aplied to 74164 through an inverter gate.
That's it, when the clock is going down on 74165 (no effect on Q7 output), the clock on 74164 is rising and a corect value is entered into shift register.

Hope you got it.