khallen
Posts: 2
Joined: Tue Nov 17, 2015 4:16 pm

GPIO expansion boards?

Wed Nov 18, 2015 8:59 pm

Hello,

Please let me know if this is not the proper forum for this question and if not then please kindly redirect me. I've done my best to search for an answer to my question but have after 5+ hours not found an answer.

I'm new to RPi but have worked extensively with Arduino (ATmega2560). My Arduino project code is complete: It controls a rather large machine comprised of a dozen stepper/DC motors and a number of sensors and what not. The ATmega2560 has gobs of IO.......but the RPi does not. While my Arduino board has satisfactory IO it does not posses higher level functionality that I need: things like Wifi, cron, SSH, etc.

I've considered the many posts on using the Arduino as a slave to the RPi but for various reasons I won't go into here, I really would rather not go that route unless I have to and so my question is as follows:

Are there GPIO expansion boards out there (other than the one below) and does anyone have any recommendations for such GPIO expansion boards? I found this one http://www.amazon.com/gp/product/B00YXH ... APE4CAYC9P but after reading the doc I don't get a warm fuzzy. Most of my IO need is for writing/output. I wish to know if there are other options for expanding GPIO?

Thank you, Keith

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mikronauts
Posts: 2623
Joined: Sat Jan 05, 2013 7:28 pm
Contact: Website

Re: GPIO expansion boards?

Wed Nov 18, 2015 11:41 pm

Take a look at:

http://www.mikronauts.com/raspberry-pi/pi-rtc-dio/

Up to 4 boards per I2C bus, 32 3v3 digital I/O per board - but limited by I2C speed
You can run the boards at 5V if not stacked to the Pi, but interfaced with 5V I2C bus (like from Pi Jumper) app note coming RSN

http://www.mikronauts.com/raspberry-pi/robopi/

Adds:

- 8 core risc co-processor
- 24 "FlexIO" (can be any one off digital in, digital out, servo, pwm, ping sensor) 5V safe
- 8 analog inputs (12 bit)
- normally used for robotics (and I also use it for DAQ / motor control)

http://www.mikronauts.com/raspberry-pi/pi-droid-alpha/

May also be useful for you, can also be used for (other than robot) control.

One Pi can support RoboPi, PiDroidAlpha and four PiRtcDio at the same time.

(it is possible to add additional RoboPi's with USB-Serial adapters)
khallen wrote:Hello,

Please let me know if this is not the proper forum for this question and if not then please kindly redirect me. I've done my best to search for an answer to my question but have after 5+ hours not found an answer.

I'm new to RPi but have worked extensively with Arduino (ATmega2560). My Arduino project code is complete: It controls a rather large machine comprised of a dozen stepper/DC motors and a number of sensors and what not. The ATmega2560 has gobs of IO.......but the RPi does not. While my Arduino board has satisfactory IO it does not posses higher level functionality that I need: things like Wifi, cron, SSH, etc.

I've considered the many posts on using the Arduino as a slave to the RPi but for various reasons I won't go into here, I really would rather not go that route unless I have to and so my question is as follows:

Are there GPIO expansion boards out there (other than the one below) and does anyone have any recommendations for such GPIO expansion boards? I found this one http://www.amazon.com/gp/product/B00YXH ... APE4CAYC9P but after reading the doc I don't get a warm fuzzy. Most of my IO need is for writing/output. I wish to know if there are other options for expanding GPIO?

Thank you, Keith
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

TheRayTracer
Posts: 51
Joined: Tue Oct 13, 2015 12:23 am
Location: Australia

Re: GPIO expansion boards?

Mon Nov 23, 2015 10:17 pm

How about the following GPIO expansion board:

http://de.aliexpress.com/item/Original- ... 29454.html

And the following looks to be the same board but different constructor as in your initial post:

http://de.aliexpress.com/store/product/ ... Id=1534002

(Sorry, the actual 52pi site is down at the moment.)

User avatar
mikronauts
Posts: 2623
Joined: Sat Jan 05, 2013 7:28 pm
Contact: Website

Re: GPIO expansion boards?

Mon Nov 23, 2015 10:35 pm

The first one does not look like an I/O expander, it seems to run one set of Pi gpio signals to three connectors.

The second one does provide 32 outputs using 4x 74hc595 serial in, parallel out shift registers.
TheRayTracer wrote:How about the following GPIO expansion board:

http://de.aliexpress.com/item/Original- ... 29454.html

And the following looks to be the same board but different constructor as in your initial post:

http://de.aliexpress.com/store/product/ ... Id=1534002

(Sorry, the actual 52pi site is down at the moment.)
http://Mikronauts.com - home of EZasPi, RoboPi, Pi Rtc Dio and Pi Jumper @Mikronauts on Twitter
Advanced Robotics, I/O expansion and prototyping boards for the Raspberry Pi

khallen
Posts: 2
Joined: Tue Nov 17, 2015 4:16 pm

Re: GPIO expansion boards?

Tue Nov 24, 2015 2:27 pm

Thanks everyone! All good options and discussion. I in the meantime have found this: https://www.tindie.com/products/land_boards/digio-128/ and I think it'll get me from point A to point B with room to spare. Thoughts? Cheers, Keith

User avatar
karrika
Posts: 1041
Joined: Mon Oct 19, 2015 6:21 am
Location: Finland

Re: GPIO expansion boards?

Tue Nov 24, 2015 4:45 pm

Great find!
Mechanics looks good and it is probably simple to program.

Massi
Posts: 1678
Joined: Fri May 02, 2014 1:52 pm
Location: Italy

Re: GPIO expansion boards?

Tue Nov 24, 2015 5:02 pm

it all depends on what you want to do with those additional GPIO.
MCP23017 is a really good chip (you can build your expansion board with a breadboard and 8 mcp23017 costing much less than 75 dollars..) but they are not good for everything.
For example, you can't use mcp23017 ports for any bitbanging (input or output), or to generate pwm signals and so on..

But yes, with 2 wires (sda and scl) you have a ton of "simple" gpio. you can drive relays, leds, simple "on off" things, and also manage interrupts (add some wires, in this case), but they are not like proper raspberry gpios

mbeffa
Posts: 13
Joined: Sun Mar 10, 2013 8:37 am

Re: GPIO expansion boards?

Wed Mar 21, 2018 5:43 pm

Check this expansion board:
  • Four layer stackable
  • Eight on-board relays
  • One 12-bit DAC output
  • Configurable interrupts
  • Eight opto-isolated inputs
  • Four open collector outputs
  • Eight 12-bit ADC channels
  • Six GPIO's
www.sequentmicrosystems.com

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