====== Raspberry Pi ======

=== Default login ===

  ***User :** pi
  ***Pass :** raspberry

At first boot on a fresh flash it is good practice to immediately run updates and configure a few options using ''raspi-config'' before proceeding to any more tuning.

===== SSH =====

<code bash>
$ sudo raspi-config
</code>

Go to ''Interface Options'' then ''SSH'' and activate it. No reboot is required.

It is good practice to have your router assign a static IP address to a RPi if you want to regularly connect to it via ''ssh''

===== Camera =====

[[https://wiki.mchobby.be/index.php?title=Pi-HQ-CAM-LENS|External wiki information on different cameras]]

==== Activating the camera ====

<code bash>
$ sudo raspi-config
</code>

Go to ''Interface Options'' then ''Camera'' and activate it. Raspi-config will propose a reboot which should be accepted.


==== Python script to take pictures ====

Navigate to a folder where you want the script to be located.

<code bash>
$ touch camera.py
</code>

Edit this file and copy the following :

<code python>
#!/usr/bin/env python

from picamera import PiCamera
from time import sleep

camera = PiCamera()
camera.start_preview()
sleep(5)
camera.capture('/home/pi/Desktop/picture.jpg')
camera.stop_preview()
</code>

//Warning, this will save to user pi's desktop, remember to change username if you aren't using user pi//

Run the script :

<code bash>
$ python camera.py
</code>

You can view the picture by either copying it to another machine with ''scp'' or by using a screen and mouse/keyboard on the pi itself.

==== Creating a Timelapse with Camera ====

You can use the built-in ''raspistill'' tool or make up your own in your choice of code language.

Example with ''raspistill'' :

<code bash>
$ raspistill -w 1920 -h 1080 - t 10000 -tl 1000 -o image%04d.jpg
</code>

This will take FullHD shots at 1 second interval for 10 seconds, naming them with 4-digit incremental numbers.

If no ''-w'' and ''-h'' options are provided, the Raspberry Pi will default to taking full sized pictures : 4056 x 3040 which will weigh approx. ~6 MB each. Also note that a Pi 4 will not be able to take these effeciently at an interval ~< 2s.

''raspistill'' has a lot of options and effects that can be activated/parametered, have a look at ''raspistill --help'' or ''man raspistill''

[[https://www.raspberrypi.org/documentation/usage/camera/raspicam/timelapse.md|Official Documentation]]
===== Scripts @ startup =====

Modify the /etc/rc.local file (requires sudo)

<code bash>
$ sudo nano /etc/rc.local
</code>

Before the 'exit 0' line at the end insert lines like this one :

<code bash>
bash /path/to/script.sh
</code>


===== Temperature checks =====

==== CPU temp ====

<code bash>
$ cat /sys/class/thermal/thermal_zone0/temp
</code>

Divide by 1000 to get °C format

==== GPU temp ====

<code bash> 
$ vcgencmd measure_temp
$ /opt/vc/bin/vcgencmd measure_temp (Full Path)
</code>


These measures were done on a Rapsberry Pi 4 running Raspbian with no heavy-duty program running, no screen or USB devices attached and at a room temperature around 20°C

  *With a 5V fan connected to 5V the temperature is stable around 35-38°C. Fan is loud and disturbing
  *With a 5V fan connected to 3.3V the temperature is stable around 41-42°C
  *With no fan connected the temperature is stable around 55-58°C


===== GPIO =====


++++ GPIO Header | 

{{composants:rpi3_gpio.png?500}}

++++

==== Using GPIO through bash ====

<code bash>
# Exports pin to userspace
$ echo "18" > /sys/class/gpio/export                  

# Sets pin 18 as an output
$ echo "out" > /sys/class/gpio/gpio18/direction

# Sets pin 18 to high
$ echo "1" > /sys/class/gpio/gpio18/value

# Sets pin 18 to low
$ echo "0" > /sys/class/gpio/gpio18/value 

# Exports pin to userspace
$ echo "4" > /sys/class/gpio/export

# Sets pin 4 as an input
echo "in" > /sys/class/gpio/gpio4/direction

# Read value of pin 4
cat /sys/class/gpio/gpio4/value
</code>