Average monthly outdoor temperature for Sopot, Abrahama in 2010--2013 (recorded with DS18B20 sensor). Average monthly temperature computed as $t_a = \sum_i^n t_i/n$, where: $t_i$ denotes measurement recorded in month $i$ (the temperature is recorded every hour BTW).

Click to see interactive version and data at plot.ly

The data shows (among other things:-) that December 2013 was really hot.

I am using Raspberry Pi version A (256 Mb) for more than a year and now I bought one Pi more--model B (512 Mb) this time. I bought a TP-Link WiFi card (TL-WN725N) and a camera as well. The plan is:

• attach the camera to the old Pi; connect Pi to WiFi network (because all four ports on my router are already occupied)
• the whole stuff connected to the old Pi (temperature, humidity (DHT-22) and pressure (BMP085) sensors as well as Logitech C270 camera) connect into the new one.

Attaching everything to one single Pi is not an option--I want the camera-equipped Pi to be more portable.

Also I did not want to install a new system but just to use what I use so far (ie the system used on the old Pi):

uname-a 
Raspberrystar.pinkaccordions.org Linux 3.2.27 + # 174 PREEMPT ... 

Simple inserting the card from the old Pi into the new one did not work (the system did not start). An upgrade is needed probably:

sudo apt-get update 
sudo rpi-update 
uname-a 
Raspberrystar.pinkaccordions.org Linux 3.10.18 + 

Now 1-Wire bus stopped working. I also can not start the WiFi adapter TP-Link TL-WN725N. Inspecting Internet forums I discovered that version 3.6.11+ of the kernel may be less problematic in this respect. Therefore, I try to downgrade:

sudo rpi-update 8234d5148aded657760e9ecd622f324d140ae891 

The above means to downgrade to the latest of 3.6.11+ versions:

pi @ raspberrystar ~ $ uname-a 
Linux 3.6.11 + raspberrystar.pinkaccordions.org # 557 PREEMPT 

Now the 1-Wire bus magically started to work. Sensors DHT-22 also work. The program I have used to read data from pressure sensor BMP085 required minor modifications and recompilation (as GPIO layout is different on Pi model B).

WiFi card also works, but require to download an appropriate driver. This one works for me (a copy is here). Other drivers, such as available here or here do not work. Compilation from sources as described here (in Polish is here) ends with an error as well.

Module 8188eu.ko can be installed as follows:

wget http://www.mendrugox.net/downloads/13 -O 818188eu.ko
## albo https://dl.dropboxusercontent.com/u/61315145/PiStuff/8188eu.ko.gz
## after download: gunzip 8188eu.ko.gz

sudo install -p -m 644 8188eu.ko /lib/modules/`uname -r`/kernel/drivers/net/wireless
sudo depmod -a
sudo modprobe 8188eu

The contents of the file /etc/network/interfaces should look like:

auto lo 

iface lo inet loopback 
iface eth0 inet dhcp 

allow-hotplug wlan0 
auto wlan0 
iface wlan0 inet dhcp 
wpa-ssid "NAME OF-NETWORK" 
wpa-psk "PASSWORD" 

One have to provide correct values for the NAME-NET and PASSWORD of course. The above settings will automatically establish a connection when the system starts.

Changing the host name

Minor thing, but I want to know easily which Pi is which:

## in the last line of /etc/hosts change host name
sudo vi /etc/hosts 

## insert host name (this file contains only 1 line with a host name:)
sudo vi /etc/hostname

sudo /etc/init.d/hostname.sh
sudo reboot

The file /etc/hosts looks something like this:

127.0.0.1 localhost 
:: 1 localhost ip6-localhost ip6-loopback 
fe00 :: 0 ip6-localnet 
ff00 :: 0 ip6-mcastprefix 
ff02 :: 1 ip6-allnodes 
ff02 :: 2 ip6-allrouters 

127.0.1.1 blackberrystar 

Camera

Updated system was cloned on a second card (Btw. for years I use Toshiba SDHC 8GB Class 10. This card is advertised as SLC but on card packaging/casing there is no word about it. SLC or not SLC I had never any problem with this card.)

Pi + camera

First picture

How to connect a camera to the Pi can be seen at one of the many videos on YouTube.

I followed instructions from How to set up the camera hardware.

Since I have not done this before:

pi@blackberrystar ~ $ sudo apt-get update
pi@blackberrystar ~ $ sudo apt-get upgrade

Now:

pi@blackberrystar ~ $ sudo raspi-config

I Choose Enable/Disable camera addon support and Memory split. I have not decided on the suggested 128 Mb for the GPU, bearing in mind that all the memory in my Pi is 256 Mb. Perhaps I am wrong and recommended 128MBs is better.

Test if it works:

pi@blackberrystar ~ $ mkdir picam
pi@blackberrystar ~ $ cd picam 
pi@blackberrystar ~ $ raspistill -o image.jpg

The result (the first picture taken) is shown on the picture.