Archive for December, 2012

2012 in review

December 31, 2012

The WordPress.com stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

600 people reached the top of Mt. Everest in 2012. This blog got about 6,900 views in 2012. If every person who reached the top of Mt. Everest viewed this blog, it would have taken 12 years to get that many views.

Click here to see the complete report.

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Short python program to change voltages in rpi gpio pins.

December 23, 2012

First I installed python:

sudo apt-get install python-pip

and then a library for gpio:

sudo pip install rpi.gpio

Once that was done, the following python script sets a high and low voltage to physical pin 11. Note: the physical pin 11 corresponds to GPIO 17.  The physical pin 6 corresponds to Ground.  For additional details and diagrams refer to: http://elinux.org/RPi_Low-level_peripherals.

import RPi.GPIO as GPIO
import time
for i in range(5):
   print ‘——————‘
   print ‘now in repetition:’,i
   GPIO.setmode(GPIO.BOARD)
   GPIO.setup(11,GPIO.OUT)
   print ‘ON…’
   GPIO.output(11,GPIO.HIGH)
   time.sleep(5)
   GPIO.output(11,GPIO.LOW)
   print ‘OFF…’
   time.sleep(5)

To run the program above, I created a script prendeApaga.py and ran it as shown below:

sudo python prendeApaga.py

Note: additional information for the rpi unit:

linux distribution: ID=debian

user: pi

password: raspberry

 available from: MCM electronics: http://www.mcmelectronics.com/

How to setup a headless rpi

December 23, 2012

I came across this link http://penguintutor.com/linux/raspberrypi-headless and followed the advise of trying to find out the dhcp address.

I connected the rpi via an ethernet cable to my wireless router and booted the rpi.

Then using ipconfig  gives the Default Gateway of my wireless router, x.x.x.1.  Then I noticed the IP address of my laptop, from which I run Putty: it is under IP Address: x.x.x.4.  Since I connected the ethernet cable for the rpi next to the cable of the laptop, to the right, I tried x.x.x.5 and it worked!