https://github.com/rm-hull/mcp23017

Schematics and build info for assembling a Raspberry Pi breakout board with multiple MCP23017 input/output port expanders
https://github.com/rm-hull/mcp23017

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Schematics and build info for assembling a Raspberry Pi breakout board with multiple MCP23017 input/output port expanders

• Host: GitHub
• URL: https://github.com/rm-hull/mcp23017
• Owner: rm-hull
• Created: 2013-02-16T14:31:45.000Z (almost 12 years ago)
• Default Branch: master
• Last Pushed: 2014-01-01T15:09:27.000Z (almost 11 years ago)
• Last Synced: 2024-10-03T12:17:45.110Z (about 2 months ago)
• Language: Python
• Homepage:
• Size: 1.88 MB
• Stars: 3
• Watchers: 4
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
mcp23017

========

Schematics and build info for assembling multiple MCP23017 input/output port

expanders with bi-directional level shifters and selectable power source

(Internal 3V3, 5V, External 5V), as below.

![Level shifter](https://raw.github.com/rm-hull/mcp23017/master/doc/level-shifter.jpg) [Attribution unknown]

Further technical details for the MCP23017 expander can be found in the 

[datasheet](https://raw.github.com/rm-hull/mcp23017/master/doc/MCP23017%20datasheet.pdf) [PDF].

Schematic

---------

![Stripboad Layout](https://raw.github.com/rm-hull/mcp23017/master/doc/schematic_bb.png)

Installation

------------

Edit `/etc/modules` and add the following entries:

    i2c-bcm2708

    i2c-dev

and reboot. Alternatively, modprobe them in. Either way, confirm the driver

has loaded properly:

    $ dmesg | grep i2c

    [   18.310467] bcm2708_i2c bcm2708_i2c.0: BSC0 Controller at 0x20205000 (irq 79) (baudrate 100k)

    [   18.332292] bcm2708_i2c bcm2708_i2c.1: BSC1 Controller at 0x20804000 (irq 79) (baudrate 100k)

    [   18.480593] i2c /dev entries driver

Then add your user to the i2c group:

    $ sudo adduser pi i2c

Install some packages:

    $ sudo apt-get install i2c-tools python-smbus

Check to see if the chip has registered (revision 2 RPi's should use icbus

1, whereas earlier revisions use 0):

    $ i2cdetect -y 1

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f

    00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 

    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

    70: -- -- -- -- -- -- -- --    

TODO

----

* Expand documentation

* Example programs

References

----------

* http://nathan.chantrell.net/20120602/raspberry-pi-io-expander-board/

* http://www.bootc.net/archives/2012/05/19/i2c-and-the-raspberry-pi/

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