i'm trying to interface my keypad with r-pi using shift register because i have only 3 more pins remaining on r-pi...i have mc74589 shift register...when i supply the input 5v in pin 16 my output from pin 9 is maximum in r-pi without pressing any key in the keypad...i gave the clock signal to pin 12 and 8 inputs have given to the corresponding pins...shift clock and output enable remains no connection along with ss/pl pin....do anyone know what is the function of SERIAL SHIFT/PARALLEL LOAD pin in the IC?please give some idea for this...


pin having on r-pi is miso,mosi,clock and one gpio

 

hi,
I cannot find a datasheet for the MC74589, can you post the d/s or a link.?

E

 

http://www.onsemi.com/pub_link/Collateral/MC74HC589A-D.PDF

 

i gave the clock signal to pin 12 and 8 inputs have given to the corresponding pins

pin 8 is GND.

Please see the page 9, Figure 12. Timing Diagram,
Please see the FUNCTION TABLE on page 7, and Figure 1. Logic Diagram on page2.

 

Hello prakash Ramamoorthy

You have studied the data sheets for that particular IC?

You say:
When I supply the input pin 16 5v in my output from pin 9 is maximum.
That's the way it works.

Later in your post you say:
I gave the clock signal to pin 12 and 8 inputs have Given to the Corresponding pins.
But PIN 8 must be connected to the negative of the power supply.

Later you mention:
shift clock and output enable connection no connection along with ss/pl pin.
Here I do not know what you mean ss/pl.
Furthermore, no PIN may be unconnected.

Now How to Use it.
I suppose you want to pass some data that are in parallel to serial.
1) - First put your data from A to H. (15, 1, 2, 3, 4, 5, 6, 7).
2) - Apply a pulse to Latch Clock(12).
3) - Make True the Input Output Enable(10).
4) - Make True the input Parallel Load(13).
5) - Make false the input Parallel Load(13).
6) - Apply 8 clock pulses Shift Clock(11).
After these 8 pulses, the data in A to H went out to Serial Data Output(9).

 

I gave the clock signal to pin 12 and 8 inputs have Given to the Corresponding pins. by that i meant that i gave the inputs to pin 15 and first 7 pins...pin 8 is grounded as per diagram...but anyway thanks...i got the output