Prerequisites:

Hardware components

• Raspberry Pi (in my case RP1 model B+)
• Breadboard (30 rows)
• Adafruit NeoPixel Ring 24 with Leds
• Adafruit CharacterLCD

Raspbian configuration

Download Raspbian image e.g. Version 9 Stretch and burn image to SD card.

Now you can boot the Raspberry Pi. Please adjust the localization / time zone on the after booting the fresh installation:

$ sudo raspi-config

# And use the following settings 
Select 4 / "Localisation Options" 
Select "I2 Change Timezone"
Select "Continent" and choose your continent
Select "Nearest City" and choose your closest city from the list 

Software-Installation

(based on https://learn.adafruit.com/circuitpython-on-raspberrypi-linux?view=all):

1. Update / Upgrade Raspbian

$ sudo apt-get update

or

$ sudo apt-get upgrade

2. Install Python 3

$ sudo apt-get install python3-pip

3. Enable I2C

Check: https://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c

4. Enable SPI

Check: https://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-spi

5. Verifiy I2C and SPI devices via

$ ls /dev/i2c* /dev/spi*

6. Install Raspberry Pi library GPIO

$ pip3 install RPI.GPIO

7. Install blinka library for supporting different python api

$ pip3 install adafruit-blinka

8. Verify blinka installation with new file:

# in file blinkatest.py

import board
import digitalio
import busio

print("Hello blinka!")

# Try to great a Digital input
pin = digitalio.DigitalInOut(board.D4)
print("Digital IO ok!")

# Try to create an I2C device
i2c = busio.I2C(board.SCL, board.SDA)
print("I2C ok!")

# Try to create an SPI device
spi = busio.SPI(board.SCLK, board.MOSI, board.MISO)
print("SPI ok!")

print("done!")

9. Setup for LCD usage

• https://learn.adafruit.com/character-lcds/python-circuitpython

  e.g. via sudo pip3 install adafruit-circuitpython-charlcd

10. Install Apache web server

$ sudo apt install apache2 -y

11. Install PHP 7.x

$ sudo apt install php libapache2-mod-php -y

12. Copy source files to Raspberry Pi

Python scripts to /home/pi
-
PHP scripts and further frontend related resources to /var/www/html, respectively var/www/html/data

13. Verify that crontab is installed (also for python)

$ sudo pip3 install python-crontab

14. Install incron for updating cronjob for triggering python script after changing alarm time

$ sudo apt-get install incron

15. Change file owner for alarm_time storage file sudo chown www-data:incron alarm_time.txt

16. Define incron for listing on alarm_time.txt file Open session with user of desire and execute the following commands:

$ cd ~
$ incrontab -e

# Add to file
/var/www/html/data/alarms.json IN_MODIFY /home/pi/update_cron.py

16. Ensure proper CHMOD settings for cron update script -rwxr-xr-x

17. Add pygame mixer libary for playing sounds

$ sudo pip3 install pygame
# restart after sucessfull installation
$ sudo shutdown -r 0

18. Add (background) service for controlling buttons

Move service definition to systemd folder

$ sudo mv button_control.service /etc/sytemd/system

Start background service and enable on boot.

$ sudo systemctl start button_control.service
$ sudo systemctl enable button_control.service

1. https://www.raspberrypi.org/documentation/linux/usage/systemd.md