Tag Archives: Raspberry

Raspberry Pi Zero Wireless Issues, Problem Found

Note: written march 2018 but only just published

Using a brand new Raspberry Pi Zero Wireless for the first time, I found the WiFi to be awful.

I used Raspbian Jessie Lite to setup the Pi Zero Wireless with a headless configuration, WiFi details and SSH enabled before the initial boot.

Round 1 – WTFreak!?

Pi unboxed and put into a nice little case for protection, power plugged up…here we go!

On booting the system the Pi connected to my WiFi and I was able to connect via SSH remotely using the hostname. The connection kept on dropping or hanging, which I thought was slightly strange.

I took a look at my UniFi AP Controller which gives statistics on devices connected, I was shocked to see the strength of the signal between the AP and the Pi flexed from 0% to 5%!?

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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.

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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

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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!

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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.

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