Many of you are into Raspberry PI's in one way or another, some are happy to just use it as a programming platform, others want to extend into the control side of things.
This Post is the start of a series to explore how you can easily and cheaply extend the capabilities of the Raspberry PI and add your own IO to it for many applications
In this video I show how to attach and use a 16 port SPI connected IO expander (The same chip as used on the PIFace Digital MCP23S17 by Microchip) and a quad channel Digital to Analog convertor from TI (The DAC8574)
I do not go into the specifics is wiring up a bread board in this post, I focus more on the setting up and using the software that is mostly already included in Raspbian but can be augmented by a very nice library called wiringpi.
On that note, for the MCP23S17 chip I also introduce a library by Gordon Henderson, the "wiringpi" which abstracts the functionality into a set of nice command line tools for use by say Python or other scripting languages, but that also is usable from within C in a way familiar to all you Arduino Wiring programmers out there. (I will be exploring this side of the library in later videos)
Schematics and links will be provided soon
for now though, here is Godons site :- http://wiringpi.com/
The MCP23S17 pdf :- http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
The DAC8574 PDF:- http://www.ti.com/lit/gpn/dac8574
In following posts I will create content detailing how to setup a PI2 from a fresh install of Raspbian (See previous video for how to install Raspbian here https://www.youtube.com/watch?v=qLo-0Tmmlrc ) and get it up and running to control various IO chips from MicroChip, TI and Atmel using SPI, I2C and the Serial interfaces. I will also investigate how to protect your PI from pending doom in the event you connect the wrong thing to the IO (ISOLATION !!)
So without further delay, here is the first video
Here are a bunch of links I found very useful in the creation of this post
http://wiringpi.com/ Gordon Henderson
http://wiringpi.com/download-and-install/
http://wiringpi.com/dev-lib/lcd-library/
http://wiringpi.com/reference/i2c-library/
http://wiringpi.com/reference/spi-library/
http://wiringpi.com/the-gpio-utility/spi-mcp23s08-and-mcp23s17-extensions/
http://wiringpi.com/extensions/spi-mcp23s08-mcp23s17/
http://wiringpi.com/examples/adafruit-rgb-lcd-plate-and-wiringpi/
http://wiringpi.com/dev-lib/piface/
http://www.ee.ic.ac.uk/pcheung/teaching/ee2_digital/MCP3002.pdf
https://www.raspberrypi.org/forums/viewtopic.php?t=6404&p=82776
https://learn.adafruit.com/downloads/pdf/adafruits-raspberry-pi-lesson-4-gpio-setup.pdf
https://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c
https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=84491