Where can I find a gated SR latch IC?

I did a google search but only SR latch ICs are for sale, not gated/clocked ones. Any ideas on a good solution for this or why this is so?

"SR" means "Set and Reset". It's a description of the input pins. "JK" might be more like what you are looking for.

But why? The Arduino processor has zillions of logic transistors inside. Why would you add another 4? Just do it in code instead.

The arduino has a limited number of IO pins so it's much easier to use an external gated sr latch as a method to add extra outputs.

You appear to be talking rubbish.

To add output capability to an Arduino - or other microcontroller - the most practical way is to use a shift register with latches - the classic one is the 74HC595 and this is presumably to what you refer.

If you wish it to drive significant current for powerful LEDs or solenoids or similar, the TPIC6B595 has outputs which are N-channel FETs. Either of these may be chained so that a significant number can be driven by only three output pins and the SPI functionality of the Arduino chip allows them to be updated extremely fast. The latch function means that all outputs are updated simultaneously.

No sort of flip-flop or latch alone can allow you to add additional outputs. Using shift registers is the most practical way to do this although you could use multiple octal “D”-type latches paralleled to eight outputs, but this is very cumbersome.

You may note the trend in digital technology, to use serial expansion busses such as USB, SATA and PCI Express.

Do a site search with '595'. There are many threads dealing with this issue - there's surely one applicable to your problem. See also shiftOut().

kolleamm: The arduino has a limited number of IO pins so it's much easier to use an external gated sr latch as a method to add extra outputs.

Explain what you are trying to do, not how you imagine it might be done...

This may be another xyproblem for all we can tell. xyproblem.info

Basically the general idea is this - you have a microcontroller with lets say 10 IO pins.

pin 0 is treated as an index. When low its index 0, when high its index 1.

The remaining 9 IO pins have now be transfored into 18 IO.

So lets assume you have two leds. One on the left, and one on the right.

When pin 0 is low, and pin 1 is high the right turns on. When pin 0 is high, and pin 1 is high the left turns on.

thats the overall idea.

That sounds like a multiplexer.

MorganS: That sounds like a multiplexer.

Ah I see!

Forgive me I'm a complete noob at microcontrollers. Are there any comptaible with arudino?

A shift register would be better. Then you can have left and right both on at the same time. There's lots of projects posted online. Some even have libraries that resemble digitalWrite().

MorganS: A shift register would be better. Then you can have left and right both on at the same time. There's lots of projects posted online. Some even have libraries that resemble digitalWrite().

Great! Thank you so much

kolleamm:
Basically the general idea is this -
you have a microcontroller with lets say 10 IO pins.

pin 0 is treated as an index. When low its index 0, when high its index 1.

The remaining 9 IO pins have now be transfored into 18 IO.

So lets assume you have two leds. One on the left, and one on the right.

When pin 0 is low, and pin 1 is high the right turns on.
When pin 0 is high, and pin 1 is high the left turns on.

Mmm, you are still having considerable difficulty explaining what you are trying to do!

You need to get this clear. It is not a 'general idea". :roll_eyes:

You are wanting to control multiple outputs OK? For the sake of argument, we will consider indicator LEDs which might have series resistors to limit them to 10 mA each.

So, how many do you want to be on at once? Just one, or a number or all perhaps? If you want to have complete control of all, then I explained this in #3. If only one at a a time, a “demultiplexer” chip will do that more efficiently so you see you must state your precise requirement. If you wish to drive a really large number of indicator LEDs (not luminaires) then a MAX7219 will drive up to 64 per chip.

74hc573 is a “gated transparent latch” (8x) if the clock is low, 8 inputs flow to 8 outputs, but when the clock goes high, the outputs latch the previous contents of the inputs. So you can share 8 pins of data in, and get 8 data out for each additional control pin you can add. 11 pins total would give 24 output pins. It’s not really a sr latch - that would have separate set and rest inputs instead of just data inputs.

A 74hc574 is similar but with 8x actual edge-triggered flip flops, so it doesn’t have the “transparent” mode.

The 595 registers people are talking about are cascadeable serial in, parallel out register with a latch in front, so you can manage any number of output pins give about 4 control pins (data, shiftclock, latchclock,...)

Hi,

Can you explain what your project is, we may be able to make your job easier?

Thanks.. Tom.. :)