SPI

[JackNoobie]

Hi, I'm new to debian linux, raspberry pi.
I have my Pi up and running flashing leds on the GPIO on certain events and emailing me on certain events. Now I want to interface to an ADC something like the MCP3008 using SPI. I've tried following instructions on installing spidev but when I include "import spidev" in my python script , i just get an "ImportError: No module named spidev". I tried numerous different methods outlined on the web but still can;t solve this one. Is there an idiot proof step by step instruction anywhere on how to install this and have it working? cheers

[vistauser]

Hallo,
have you followed the instructions from Alex?

Analog < > Digital converter programs (NEW 13 December 2012)
=====================================
To make use of atod.py, dtoa.py and dad.py you MUST have SPI enabled

sudo nano /etc/modprobe.d/raspi-blacklist.conf

make sure there IS a # before blacklist spi-bcm2708, so it looks like this...
#blacklist spi-bcm2708

Adding this # prevents SPI being disabled. If you had to change it, you'll need to
reboot to activate SPI.

sudo reboot

You will need to install the Python SPI wrapper: (Python 2.7)

cd ~
git clone git://github.com/doceme/py-spidev


If you don’t have git installed, the above command will fail. Install git with...

sudo apt-get update
sudo apt-get install git

When asked if you want to continue, answer Y
then, after installation, try again
git clone git://github.com/doceme/py-spidev

then it should copy the files into a directory called py-spidev. Go there next

cd py-spidev/
If you have already installed WiringPi for Python the next step (python-dev) may not be necessary...

then type
sudo apt-get install python-dev
y (to confirm).

sudo python setup.py install
And after that you should be able to use the ADC/DAC programs. No further reboot needed.

[JackNoobie]

Thanks, Yes had found this and have done all this. spidev is listed when I do lsmod, but still comes up with the error when I add "import spidev" . I'd rather not rbuild the whole thing again from scratch but might have to if I can't get anywhere with this.
What should I check to ensure its all installed properly?

[trouch]

take a look on WebIOPi
it include a full I2C/SPI python stack with no dependency.
it also have many devices drivers, including MCP3008
https://code.google.com/p/webiopi/wiki/MCP3000
https://code.google.com/p/webiopi/wiki/ ... on_example

[JackNoobie]

Thanks for you help (vistauser) and suggestions (trouch -will look at that some day soon).
After much playing around I now discover it works in Python 2.7 but does not work in Python 3 ("No module named spidev"). Does that make any sense?
Anyway, I'm happy to continue with 2.7

[trouch]

thats the cool thing with webiopi
none of official i2c or spi python module works with python 3
webiopi i2c/spi stack works with both python 2 and 3 !

[Jupiter1]

I am trying to use the SPI interface as pi user. but when I do this I get
>>> spi.open(0,0)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IOError: [Errno 13] Permission denied
>>> exit

But if I use Python as sudo then it works ok. How do I use teh SPI as a normal user pi please?

Many thanks

[texy]

Writing to the GPIO port requires admin privileges, so Sudo will be required if not logged in with appropriate log in.
Don't think there is any way around it,
Texy

[notro]

You could also change the permissions on the device:
sudo chmod 666 /dev/spidev0.0

To make it permanent, add to /etc/rc.local
A professional solution would be to make an udev rule, but that is beyond me.

[bhollehday]

Im having a similar issue getting SPI to work. I noticed when I installed git clone, it ran through a couple errors like the links were out of date or something. Im running python 2.7.3

failed to fetch http://mirrordirector.raspbian.org/rasp ... aremhf.deb 404 not found

It had like 5 or 6 of these in the command line. Any ideas?

I keep getting no such module name spidev error.

Im trying to get my OLED up and running but no luck!

This is what ive been using...
https://learn.adafruit.com/adafruit-ole ... ur-display