Arduino I/O Expansion

ADWSystems · Feb 5, 2015

As much as I don't want to go with a microcontroller, it appears the quickest path between point A and B will be by programming instead of hard wire dedicated circuits. So I am looking at the Arduino family of products as my path forward. Project #1 is I/O heavy. Using a micro, it appears I will need 3 inputs and 3 outputs per "station", and at least 8 stations. To start I need 24 inputs and 24 outputs, plus other functions that are required but have not been incorporated yet.

So my question is: Has any one developed an I/O expansion module for the Arduino to expand the amount of I/O that can be addressed by the chip? I have an idea forming, but would rather see if this has been done before and/or if there is a module available to do it before I roll my own.

ronsimpson · Feb 5, 2015

This is a I2C board. So the pins are I/O not I only or O only.
https://www.sparkfun.com/products/8130

SPI 8 outputs using 74HC595 (I think they have a 8 in board but I can't find it)
https://www.sparkfun.com/products/10680

MrAl · Feb 5, 2015

ADWSystems said:
As much as I don't want to go with a microcontroller, it appears the quickest path between point A and B will be by programming instead of hard wire dedicated circuits. So I am looking at the Arduino family of products as my path forward. Project #1 is I/O heavy. Using a micro, it appears I will need 3 inputs and 3 outputs per "station", and at least 8 stations. To start I need 24 inputs and 24 outputs, plus other functions that are required but have not been incorporated yet.

So my question is: Has any one developed an I/O expansion module for the Arduino to expand the amount of I/O that can be addressed by the chip? I have an idea forming, but would rather see if this has been done before and/or if there is a module available to do it before I roll my own.

Hello,

Once you get into microcontrollers you will wonder why the heck you did not get into these things sooner. That's all i can say because you dont realize the power in these things until you start using them. Then you'll never want to be without them. So much functionality in such a little package.

I once built a very nice controller with lots of memory and functionality, starting with a Z80 CPU. Using a decoder for i/o and stuff like that. That was an entire board though, measuring about 3 inches by 6 inches. Now i get almost the same functionality in a single DIP chip, and if i wanted to go SMD it would happen in a tiny package like 1/2 inch square or something. Minimum support components too. I only need a couple caps and good voltage reference for most of the stuff i do. The built in ADC is so darn nice it's almost too hard to design without it these days.

There's a little bit of a learning curve, but once you get past that you will never regret taking the time to learn this.

ADWSystems · Feb 5, 2015

MrAl said:
Hello,

Once you get into microcontrollers you will wonder why the heck you did not get into these things sooner. That's all i can say because you dont realize the power in these things until you start using them. Then you'll never want to be without them. So much functionality in such a little package.

I once built a very nice controller with lots of memory and functionality, starting with a Z80 CPU. Using a decoder for i/o and stuff like that. That was an entire board though, measuring about 3 inches by 6 inches. Now i get almost the same functionality in a single DIP chip, and if i wanted to go SMD it would happen in a tiny package like 1/2 inch square or something. Minimum support components too. I only need a couple caps and good voltage reference for most of the stuff i do. The built in ADC is so darn nice it's almost too hard to design without it these days.

There's a little bit of a learning curve, but once you get past that you will never regret taking the time to learn this.

I know how powerful they are. Notice I didn't say I haven't used them. Just that I was trying not to deal with H/W and S/W. I spent almost 10 years programming 8051s, Z80s, and PICs. Since I'm no longer in that industry, I don't have access to all the nice tools for troubleshooting ground-up design. I'm thinking of compromising by using an Arduino. I thought the circuit would be easy enough without a micro, but the discrete logic is taking to long to perfect and becoming too large of a circuit to work with all the functionality is added.

ADWSystems · Feb 26, 2015

ronsimpson said:
This is a I2C board. So the pins are I/O not I only or O only.
https://www.sparkfun.com/products/8130

Do we know if there is an example sketch out there for this shield? The code I found so far would need to be ported into an Arduino sketch.

ronsimpson said:
SPI 8 outputs using 74HC595 (I think they have a 8 in board but I can't find it)
https://www.sparkfun.com/products/10680

I would (now) be interested in a SPI 8 Input chip. Anyone know the number? (looks like neither Ron nor I can find it)

granddad · Feb 26, 2015

Going the micro way will un-complicate the pcb however there are more things to investigate, what size of code is expected and what language , what speed MIPS , what power requirements. what about alternate pin selection
as an example I have a PIC24EP512GU810 on a breakout board , 70MIPS 51 I/O pins host of peripherals would do your project , nothing else required. not even a xtal !

Similar commercial part https://microcontrollershop.com/product_info.php?products_id=5283

Arduino I/O Expansion

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