How does a Bidirectional Shift Register work and how to control 10x 74HC595 in parallel?

How Bidirectional Shift Register work? Can someone give me a detailed information?

And also, How can I control 10 parallel shift register (74HC595) by using a shift register (74HC595)?

I can't make much sense of this question

I would guess (having never used one) that a bidirectional shift register shifts in either direction as it's name indicates, so data can be shifted into the register and back out.

A 74HC595 is not bidirectional.

without knowing in what way you want to control something (what you want it to do, it's pretty hard to say how to control it.

74xx595 is cascadable.
See the attached schematic.

It seems that often here the hard part is figuring out the question.

I'm not sure that cascading is the answer since I'm not sure exactly what controlling means. Somehow that seems different than just cascading them. And what does bidirectional have to do with it anyway?

You can merge cascaded 74HC595 (parallel outputs) with the cascaded 74HC165 (parallel inputs) like into the attached schematic.

With the shared lines.

http://web.archive.org/web/20041209003715/hom...lls/Software/ShiftRegister/ShiftRegister.html

Hi yp_ng


Have you done any binary maths before because this is where you need to start before you try and understand shift registers

If youve worked on a washing machine before and replaced the timer old school timers which were motorised you will remeber how they are made and what the cam does is it has a clock cycle for every tick of the clock a switch is activated This would also help you understand how a shift regsister works or you could think parrarell to this

Or if you gave ever opened a music box the old drum used to make all the spings jump to produce music

Another similar scenario not quite what a shift register is but elementry start to understanding this in visual format

Binary maths for you

http://www.math.grin.edu/~rebelsky/Courses/152/97F/Readings/student-binary


Next Read the datasheet then
Have a look at this page this is an interactive giude of how a shift register works

http://conductiveresistance.com/2011/02/28/interactive-595-shift-register-simulator/


Think of a shift register as binary number shifted N amount of times

Lets see take the number 10 conver this to binary

1 dec = 0001 bin

Now lets shift this binary number one place at a time

Watch what happens Picture a clock second hand as you read

0001 left shift 1 clock 0 = 0010 tick "
bring this down again

0010 left shift 1 clock 1 = 0100 tick
bring this down again

0100 left shift 1 clock 2 = 1000 tick
bring this down again

1000 left shift 1 clock 3 = 0000 tick

Enable output

OUTPUT = 1 final result after 4 counts or n - 1

I land up with 1 at the output serial output



So what happens to the bit in the number

Thats a very basic operation of what happens in a shift register Im shifting the bits out of the register right to left

In Binary or programming langauge we say The way we express a right shift or left shift is by writing

The following "One setp further to go and think about "

So lets take our above example again

0001 left shift 1 clock 0 = 0010 tick "

Lets store the number this time in a container

MyNumber is a container we call the container a name this holds our 4 bit binary number

MyNumber = 0001

MyNumber = MyNumber

Start after this with a 555 and a 4017 then
I would still progress this to pic micro then you can learn to programtically create 74HC595

One chip acting as the master the rest as slaves

As I'm doing a game call 'mastermind',and I using pic18f45k22. Keypad is needed to control the color(RGB led),as pic18f45k22 does not have enough pins.
This game need 4 RGB led in one row,total game need 10 rows,and each row have 4 feedback(bicolor led) to tell the player which color correct and location of the color correct.
So as you can see,there are too many pins,so I think need to use shift register,
By the way,the player can change the colors by pressing left or right,so which shift register can I use?74hc595 or the bidirectional shift register?
Thank you.

i wouldnt do what your doing that way Id use multipexing but without a schematic Well same old story isnt but looking at the device datasheet You have two modes on the MSSP Port 3-wire SPI (supports all 4 modes)- I2C™ Master and Slave modes with address mask 3* 8 bit ports

Need to know how many keys for the keypad first as this is going to decrease the number of pins you can use on the ports minus of course your comms pins which accounts for three so far meaning only 21 pins left , "Not including keypad matrix"

So thats keypad matrix and you need a display matrix you also need 3 pins for your bus

Back to the drawing bourd and do the hardware design first and decide what you need or more importantly what you have to have

You also need after doing this at least some type of plan algorythm a to hwo you might put this idea of yours into progress may be a flow chart showing user interaction

Truth tables etc etc

Most important of all a hardware diagram



Would you not be better off with FPGA ?

" Wena injongo umsebenzi " , "A boer maak a plan"

"Super news" Wont take you to long to explain this one will it ?

There you go contact the DHSS in the UK and ask them to send you on a course

No worries hmmm

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The course is possibly $20 000 with the unemployed populations rising steadily still no courses and we havent got to FPGA or VHDL yet Ho Ho

Hi Mr Mark, I'm a newcome eeweb. Nice to see you Mr.


So.
I have a little question, maybe you have a answer for my question. would you want?

Thanks.

well - I'm not clear on what you need.

You mentioned RGB LEDs which are Red, Green and Blue but then say there's 4 feedback for bicolor LEDs, which are often red and green or red and yellow. RGB would take 3 outputs and bi-color 2. I don't understand what "4 feedback" means - is this 4 wires where one is common or 2 wires to each color of bi-color LED?

I assume you don't want to vary the brightness of each of R,G and B so you can have all colors or all brightnesses, rather than just on and off for each color - that would be much more complicated.

If you just want red or green LEDs then only 80 outputs are needed.

You can probably ovrerdrive the LEDs a little as they're not on all the time but be careful. Most LED data sheets allow more current if the LEDs are pulsed, but the decreased duty cycle more than compensates for the increased brightness if you follow the datasheet.

I'm not sure what the shift register will get you - you still have to load it. Your pic should be fast enough to just multiplex the LEDs directly (again, depending on how much else you need to do.) The led update rate should be 50 Hz or more so each of 8 groups of 16 LEDs can be driven at 800 Hz - not real fast.

I'd just multiplex the LEDs. With 15 outputs you can drive 128 LEDs where I THINK you need to drive 120 LEDs (10 rows of 4 each 3 color LEDs?). I have done something like this for an alphanumeric display with 8 P-mosfet and 16 N-mosfet drive transistors. I used opto-isolators to shift the drive for the P-mosfets from the processor so the on drive to the mosfet was 12V and they were powered with 5V. I was driving each LED 1/8th of the time. I used single color ultra-bright LEDs so I still had to limit the current to the LEDs for use indoors.

The processor you selected has 24 outputs which could work for this, depending on what else you want to do. Keypads come in lots of flavors, serial, multiplexed (4 I/O for 16 keys) or individual keys so this could work depending on your other I/O needs.

The display is just one aspect of this and it's hard to give good advice without knowing about the whole thing.

Another thing - I'd do as much as possible in software. It's much easier to change than the hardware. Programming can be frustrating and time consuming but in the end it usually beats the hell out of lots of jumper wires.

Hi yp,
You need to upload a circuit diagram and program code of all that you have produced so far, so that we can see exactly what you need to progress.

Hmm same old storyNo diangrams No Flow charts and No idea

You have to start with some type of plan You have to prduce some type of schematic otherwise you might as well stick your head in the sand like an ostridge does