i need to made 100 digital ports I/O

hello ,

i need to expand arduino digital ports can help me ,


i have 74hc595 but i need to control pins


Input or output, or what combination of each do you need?


You may use "matrix-method". In most cases you can "control" 100 inputs or outputs with 20 pins on your microcontroller.
But if this is posssible with your project we need to know more about it.

As always, what you really need to explain, is what you actually want to do, not how you imagine you want to do it.

In this case, you say "100 digital ports". The question however, is "Why?" What you you want to do that you think requires those ports?

This is referred to as "The XY Problem".

Here’s how I would do it, using <SPI.h> library to send the data out quickly.
Expand to 13 registers, 104 outputs.
Can send out 13 bytes using individual names (byte0, byte1, etc). or call the bytes from an array (byteArray[0], byteArray[1], etc.)

first thanks all for replay , i need to control output 100 led on/ off from my pc i have arduino uno r3 + 74hc595 , my progect home automation but i need to control 100 leds on/off


OK, we're getting somewhat closer but it's a little like pulling teeth. :astonished:

What sort of LEDs are these (how much current does each require), and what is the purpose? Are they for indicators, or a display, or as luminaires (that is, to light up a whole room)?

How many need to light up at the same time, or must light up separately, and how quickly?

Buy a WS2812B led strip.
Then all you need is 1 output pin and one of Crossroads 1284 boards.
You can turn on any combination and almost any color per LED.

Unless he wants 3W LEDs. Or something else.

At this point, we simply have no idea.

Unless he wants 3W LEDs. Or something else.
At this point, we simply have no idea.

What do they say about pulling hens teeth.

i need to control 100 light(relay) how to control this from arduino ?

We are trying to help you.
Give us more information.
Tell us what you have done so far.
What is your budget?
What are your design criteria?

Hands up in the air. . .

i need to control 100 light(relay)

This IS some more information.

I’d be looking for I2C relay boards that are chaineable to 100 total relays. Something like http://www.sainsmart.com/16-channel-12v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html (which is relays and drivers only), plus http://www.iascaled.com/store/I2C-RELAY16 (which provides up to 8 chaineable I2C drivers that connect to the bare relays.) That would be less than $3/relay, which is probably cheaper than any fully homemade solution.

Be careful, though. Many of the I2C IO expanders only allow 8 different i2c addresses, so 8-port relay modules might not let you get to 100 relays without some extra effort.

You could use my 12-shift register board, control 96 LEDs from the shift registers and 4 more from IO pins.
Will need 100 current limit resistors as well.


Or use two MAX7219 to drive up to 128 LEDs, no resistors needed. This board breaks out 2 pins per LED, makes it easy to wire them up.

This IS some more information.

Unfortunately, quite conflicting and basically, useless.

Personally, I have no intentions here of making suggestions until he explains what he actually proposes, because we still have no idea what it is.

Giving ever less information with each posting and randomly throwing together the words "control", "100 light", "relay" just doesn't "cut it".

I have no qualms about CrossRoads marketing his boards - they are clearly terrific and it is hardly going to make him a millionaire (unfortunately :grinning: ) - or you suggesting a quite different alternative for a different problem entirely, but as has been thus demonstrated it is likely to be a total waste of time on all our parts if as would seem to be the case, he is not capable of a sensible explanation. :astonished: