How can I interface the PI to sensors ?

Hi Steve,

in your case I'd start of the playground on the arduino website, that's a good starting point. There are quite a few examples and you may also want to buy one of those simple shield with a lot of different hardware (I think it is called dangershield?!). If you want to get your hands dirty with I2C or SPI the BusPirate may be intersting for you, it's a good board to learn/understand how bus communication works.

It's probably also a good idea to learn a bit C, if you plan on working with hardware with the arduino or the R-Pi.

Hope I could help a bit

You might also be interested in the One-Wire File System. http://owfs.org/

This exposes some of the available sensors in a way that makes them easy to access.

Z

The elinux wiki is a good place to watch as information on interfacing progresses.  This page indicates that right now the GPIO, SPI and I2C drivers are a work in progess:

http://elinux.org/RPi_Low-level_peripherals#Driver_support

Like many aspects of the project, I'm sure this will improve rapidly once boards start getting into more hands.  Also on that page, there is an interesting example of memory-mapped GPIO:

http://elinux.org/RPi_Low-level_peripherals#Code_examples

I think we'll eventually see easy-to-use abstractions for interfacing like Matt Richardson has done for Python on the BeagleBone:

http://blog.makezine.com/2012/03/14/how-to-get-started-with-the-beaglebone/

On the hardware side, I'm sure there will be plenty of interesting interface boards.  I'm very excited to see how Adafruit's Pi Plates progress:

http://www.adafruit.com/blog/2012/03/14/adafruit-experimenting-with-pi-plates-for-raspberry_pi-shields-for-the-raspberry-pi/

Cheers,

Drew

low-level driver support looks great... thumbs up

I built my own GPS board but has a separate microcontroller that can talk to sensors. The RPi and the MCU talks via serial connection through the onboard UART on the headers.  So in essence, I can send a command to the MCU to grab sensor data. Something like  root:>$GPS#LAT? root:>$LED1#ON? root:>$SENS#TEMP1? root:>$SERV#145?  of course, the MCU would have to be programmed to grab sensor data continuously and respond to command received from its serial port  that's just example. its better (at least for me with MCU experience) than messing around with Linux SPI/I2C kernel drivers.  also makes it easier to interface with higher level applications like php/java/etc.

if anyone will be using the gpio ports directly (i.e., w/o an expansion board such as adafruit or gertboard) I strongly recommend that they use buffers as found on this page: http://elinux.org/RPi_Tutorial_EGHS:GPIO_Protection_Circuits.

The LED tutorial works for sure with the shell script previously mentioned.

Julian mentioned the Bus Pirate if you're going to be messing with I2C or SPI, and I second that.  It's a very cheap but highly useful little gadget.  You can even use it as a very slow 'scope, lol.  Here are some links for it:

• http://dangerousprototypes.com/docs/Bus_Pirate
• http://dangerousprototypes.com/docs/Common_Bus_Pirate_cable_pinouts
• http://www.sparkfun.com/products/9544
• http://www.coolcomponents.co.uk/catalog/pirate-p-671.html
• http://www.youtube.com/watch?v=fwE4PYCmACQ
• http://www.youtube.com/watch?v=8XiXXxV9nRI
• https://github.com/tgvaughan/PirateScope

Morgaine.

Hi Morgaine, that is very interesting, thank you for the recommendation.

Also you could try the wireless approach: http://www.element14.com/community/thread/18613

Morgaine, I have taken your advice and bought a bus pirate with assorted leads (arrived yesterday) so those links will come in useful i'm sure :-)

Simon, I will be trying the wireless approach :-)

Steve