Tag Archives: Raspberry

ARPIC – Time Check Boot Script

In the event of a power outage, an analogue power socket timer switch will simply turn off.   When then power returns, the unit is not aware of how long the power has been out for and the timer will continue from when the power cut.

If a digital timer is used, on power being restored, the time should be correct with your on/off schedule preserved.

When using a Linux system (Raspberry Pi) and Cron to set a scheduled task, if a power cut occurred within the time an action was supposed to initiate, this window will be missed as when the system power is restored the action event would have passed and won’t be initiated until the next scheduled time.

For the ARPIC or Linux system to act like a 7 day digital timer a script is used on start up to check the time.

Continue reading ARPIC – Time Check Boot Script

ARPIC – Raspbian Light Stretch NTP

Whilst setting up a new APRIC I noticed that the time was not updating as expected, no update on boot.

I have not setup an RTC on this unit yet, but NTPD would need to be installed anyway to updated the RTC later.

It appears in the Jan 2018 release of Rasbian Lite Stretch does not have NTPD installed as default.

A quick way to check the time and date configuration is to use timedatect1

Continue reading ARPIC – Raspbian Light Stretch NTP

ARPIC, Install Raspbian Lite onto a Raspberry Pi

ARPIC – Another Raspberry Pi Controller

Hardware  :

Raspberry Pi

4GB or larger Micro SD card

Network connection – cable or WiFi

PC with an SD card reader (Windows OS in this example)

Software:

For help getting Raspbian onto your SD card, take a look at these pages;

https://www.raspberrypi.org/documentation/installation/installing-images/

https://www.raspberrypi.org/documentation/installation/installing-images/windows.md

Lets get started!

Continue reading ARPIC, Install Raspbian Lite onto a Raspberry Pi

Raspberry Pi Thermal Probe

How to read a temperature probe, save the value to a MySQL database and then show the value on a webpage or just show the value with no database.

 

See this link for how to setup a DS18B20+ thermal probe with a Raspberry Pi, these instructions  are the best that i have come across for this and will cover the bullet points below :

  • Enabling the 1 wire features in the Raspbian OS
  • Physically connecting the probe via a resistor to the RPi
  • Instructions on how to read the probe and a script example

https://www.modmypi.com/blog/ds18b20-one-wire-digital-temperature-sensor-and-the-raspberry-pi

Once you have followed the above steps you should have a working temperature probe, that’s great.. but what can you do with it now!?

For the piTank/piGrow projects,  I started off by just using the script provide in the instructions above, modifying it slightly and using that to display the temperature value on the piTank web-page. Using some JavaScript you can make the box’s refresh every x seconds, running the probe read script and showing a new value without the need for a page reload.  I call this a ‘live’ reading.

Continue reading Raspberry Pi Thermal Probe

Raspberry Pi Slideshow .PPT .PPTX .ODP

The information below will help you to setup a Raspberry Pi with Raspbian OS that will play a slideshow/PowerPoint presentation using a PPT/PPTX or ODP file.

The system will be setup to automatically login to a desktop, load Libre Office Impress (PowerPoint alternative) and run a slide show presentation with custom slide show settings defined.

Please note, MS Powerpoint slideshows might not display 100% correctly in Libre, you can save from MS PP to an open format or to ensure an output as expected, just grab Libre office for PC or Mac, it is Free after all!!

Why:

Instead of using a costly full blown MS Windows desktop PC we can use a Raspberry Pi that not only costs hundreds of pounds less to buy but also consumes a minor percentage of power that a full desktop uses as well as being small enough to attach to the rear of the display device.

Continue reading Raspberry Pi Slideshow .PPT .PPTX .ODP