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Making OSPi Its Own LAN Access Point

By Kurt Euler | Jan 16, 2019 | 0 Comments

This document describes how to set up an “ad hoc” network on your Open Sprinkler Pi (OSPi) device. This type of network allows you to manage your OSPi without the need of a dedicated router or pre-existing netowork. You install and configure certain software on the RPi that causes it to present it self as a network. This network appears as any other does on your mobile device or laptop, as show in this example from an iPhone:

Once you connect to the network, you open the Open Sprinkler App (or Web UI if using a laptop) to administer Open Sprinkler.

Why would you do this?

Consider setting up an OSPi ad hoc network (we’ll call this the OSPi network) if:

  • There is no available WiFi network. An OSPi network is useful in cases where there is no existing network
  • The existing WiFi network isn’t useable. In some cases, an existing WiFi network isn’t practical to access. For example, you might have a rental property, whose grounds are watered by an OSPi system, and you don’t want the unreliability (or liability) of connecting the OSPi to the tenant’s WiFi network.

Why would you not do this?

Don’t set up a OSPi network if:

  • You require remote administration. Ad hoc networks are by definition standalone. They aren’t connected to the Internet, and hence you can’t administer devices on them via the Internet. Similarly, you can’t have log files forwarded to you.
  • You need frequent in-place software/firmware upgrades. You can’t easily upgrade/update the OSPi software when you have an OSPi network, since upgrades are normally conducted over the Internet. (This isn’t an important factor, though, since the current Raspian and Open Sprinkler code is quite stable.)
  • The OSPi network would be out of range of an administering device. I’ve found that I can connect to the OSPi network (even one using a Pi Zero W) with my iPhone and laptop up to 50′ away, with several intervening house walls. However, you don’t believe you’re administering device will always be within range of the OSPi network when needed, then this setup isn’t likely for you.

Source material

All steps in the present OSPi network setup procedure below are directly distilled from this Stack Exchange Web page. This Web site has the only set of Pi ad hoc network configuration instructions I’ve found that works for the Stretch version of Raspian. This source site also has more explanations of commands that is presented in the present document, and additionally includes a useful troubleshooting section.

Note that there’s nothing in the present network setup instructions that’s Open Sprinkler specific. You can set up an ad hoc network for any number of purposes. 


Have the following requirements in place before proceeding.


  • An Open Sprinkler Pi (OSPi) board from Open Sprinkler.
  • A standard 24VAC power supply for sprinkler valves.
  • A Raspberry Pi (RPi). I’ve successfully set up a Raspberry Pi Zero W, but Pi versions 2 (with WiFi dongle) or 3 should work fine.
  • A microSD card, 8GB or higher.
  • A wired keyboard and monitor.


  • Raspbian Stretch Lite (Installed prior to these instructions)
  • Random number tools (Installed in these instructions).
  • git-core (Installed in these instructions).


  • Access (at least temporary) to the Internet via WiFi.
  • The microSD card has the Stretch version of Raspian installed on it, and the microSD card is installed in the RPi.
  • The RPi is either:
    • installed on the Open Sprinkler board, or
    • temporarily freestanding. (You can install the RPi on the OS board at the end of the ad hoc setup.)
  • The keyboard and monitor are connected directly to the RPi.
  • The RPi is booted up. You can boot the RPi according to your preferred hardware configuration:
    • If the RPi is attached to the Open Sprinkler board, connect the powered 24VAC adapter to the OS board.
    • If the RPi is freestanding (for all but the final boot), connect powered 5V USB adapter to the RPi.


  • Have available the name (wpa-ssid) and password (wpa-psk) of the Internet-connected LAN.
  • Have in mind a different name (wpa-ssid) and password (wpa-psk) for your OSPi network that you’ll configure. Note that the password should be at least 8 characters long.
  • Nave in mind an IP address for the OSPi network access point. Normally it is 192.168.x.1, where “x” is a number between 1 and 254.

Set up the OSPi network

Perform the steps in the sections below to configure your OSPi network:

Log in as root

pi@raspberrypi:~ $ sudo -Es
pi@raspberrypi:~ #

(If you log in as root, , you can enter subsequent commands without the need to type “sudo” at the start.)

Localize the RPi

If you haven’t localized the RPi yet do so now. For example, change the English keyboard layout to one more suited.

Tip: Configure localization via the raspi-config utility:

pi@raspberrypi:~ # raspi-config

Connect to an Internet access point

If you haven’t done so already, configure a connection a WiFi connection to the Internet. (This is a temporary setup to get required software.)

1] Open file /etc/network/interfaces with the nano text editor:

pi@raspberrypi:~ # nano /etc/network/interfaces

2] Replace all text in the file with the following text, substituting ssid and password for your WiFi’s credentials. (Keep the quotes!).

auto lo

iface lo inet loopback
iface eth0 inet dhcp      #an optional line

allow-hotplug wlan0
auto wlan0
iface wlan0 inet dhcp
        wpa-ssid "ssid"
        wpa-psk "password"

3] Save and close the file. (Ctrl-x, y, Enter.)

4] Reboot the RPi:

pi@raspberrypi:~ # reboot -h now

4] Verify that the RPi has connected to your router by displaying the network status:

pi@raspberrypi:~ $ sudo -Es     #log in as root
pi@raspberrypi:~ # ifconfig

If the RPi connected to the internet, the wlan0 section will include the line “inet w.x.y.z“, where w.x.y.z is the IP address of the RPi (as assigned to the RPi by you router).

Update/Install Software

Update Raspian

If you haven’t done so already, update Raspian with the usual commands:

pi@raspberrypi:~ # apt-get update
pi@raspberrypi:~ # apt-get upgrade

Install rng-tools and git-core

Install rng-tools and (if not already installed) git-core as follows:

pi@raspberrypi:~ # apt install rng-tools
pi@raspberrypi:~ # apt-get install git-core


  • rng-tools helps speed up the generation of random numbers for the “supplicant”.
  • git-core enables you to download programs, such as the Open Sprinkler firmware, from the git hub.

Install the Open Sprinkler firmware

If you havn’t already done so, install the Open Sprinkler firmware. The steps below are taken from the OSPi documentation.

Note that the command starting with “git clone…” might appear word wrapped at the end. But be sure to type the entire text on one line.

pi@raspberrypi:~ # cd ~
pi@raspberrypi:~ # git clone https://github.com/OpenSprinkler/OpenSprinkler-Firmware.git
pi@raspberrypi:~ # cd OpenSprinkler-Firmware
pi@raspberrypi:~ # ./build.sh ospi

Enable journaling

pi@raspberrypi:~ # cd ~
pi@raspberrypi:~ # mkdir -p /var/log/journal

    # The following command might report a "Cannot set
    # file attribute..." error when executing.
    # You can ignore the error.
pi@raspberrypi:~ # systemd-tmpfiles --create --prefix /var/log/journal 

Disable classic networking

pi@raspberrypi:~ # systemctl mask networking.service
pi@raspberrypi:~ # systemctl mask dhcpcd.service
pi@raspberrypi:~ # mv /etc/network/interfaces /etc/network/interfaces.orig

Insert text into file /etc/resovconf.conf:

pi@raspberrypi:~ # sed -i '1i resolvconf=NO' /etc/resolvconf.conf

Configure systemd-networkd and systemd-resolved

pi@raspberrypi:~ # systemctl enable systemd-networkd.service
pi@raspberrypi:~ # systemctl enable systemd-resolved.service

Create a symbolic link

Create a symbolic link to file /run/systemd/resolve/resolv.conf:

pi@raspberrypi:~ # ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

Configure wpa_supplicant as the access point

1] Open file /etc/wpa_supplicant/wpa_supplicant-wlan0.conf with the nano editor:

pi@raspberrypi:~ # nano /etc/wpa_supplicant/wpa_supplicant-wlan0.conf

2] Enter the following text, but replace the text RPiNet and password with the OSPi network name and password you decided on in section Required:information above.


  • Don’t put spaces before or after the “=” signs.
  • Select a password that’s at least 8 characters long.
country=US          # Replace US with your contry acronym.
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev

    ssid="RPiNet"   # Replace RPiNet with the desired network name. Keep the quotes!
    psk="password"  # Replace password with the desired network password. Keep the quotes!
    frequency=2437  # See (*) below.

*For more information on the frequency value, see https://en.wikipedia.org/wiki/List_of_WLAN_channels.

3] Save and close the file.

4] Set privileges for file /etc/wpa_supplicant/wpa_supplicant-wlan0.conf:

pi@raspberrypi:~ # chmod 600 /etc/wpa_supplicant/wpa_supplicant-wlan0.conf

Enable the supplicant service

pi@raspberrypi:~ # systemctl enable wpa_supplicant@wlan0.service

Set up a stand alone access point

1] Open file /etc/systemd/network/08-wlan0.network with the nano editor.

pi@raspberrypi:~ # nano /etc/systemd/network/08-wlan0.network

2] Enter the following text, but replace the sample network access point IP address ( with IP address you decided on in section Required:information above.

Address=  # Replace with your desired IP address

3] Save and close the file.

Reboot the Raspberry Pi

Proceed according to the RPi’s connection during the setup:

  • If you installed, the OSPi network with the RPi freestanding, shut it down, install it on the (unplugged) Open Sprinkler board, then connect the 24VAC power source to the OSPi.
  • If you set up the OSPi network with the RPi installed on the Open Sprinkler board, simply reboot:
pi@raspberrypi:~ # reboot -h now

Open the Open Sprinkler management interface

You should now be able connect to the OSPi network by selecting the network name in the list of networks displayed on your device. Then open the Open Sprinkler management interface using the IP address you specified (e.g.,

If using a browser, just type in ipaddress:8080 into the URL field.

If using the OSPi App, specify the ipaddress:8080 in the Manage Sites screen.

Hydroponics phase 2 completed

By Kurt Euler | Aug 8, 2016 | 0 Comments

I recently concluded a couple upgrades to the hydroponics rig.


1) Conversion from constant-flow to fill-and-drain

I read various internet post about some of the benefits of fill-and-drain design over the constant-flow design. Each has its merits, but I like the idea of servicing drained planters, and managing the nutrient liquid when all liquid is in the basin. This is the case when the pump is off in a flood-and-drain system.

To implement this, I devised and deployed check valves as shown in this diagram:


Here’s a close up of a check valve:


For detailed information about this solution, see this instructable.

2) New nutrient management system

The two 5-gallon buckets I’d been using had too low a capacity in both water and flow handling. I replaced them with a 20 gallon trash can from Home Depot. For the plumbing, I constructed a rig (drawing in progress, just below) which is submerged in the can.



Altogether, much nicer to uses maintain

Phase 2 Pic


Note that the aforementioned check valves are denoted by the three yellow drawn boxes along the right edge.

Phase 3 plans

  1. Move the connective plumbing from each planters end-caps to the tops and bottoms of the planter pipes. (See first drawing way above for sample new positions.)
  2. Optimize some of the plumbing on top of the basin.
  3. Experiment with “triple layer” planter pipes to keep light out of the planter interior.

Phase 4 ideas

  1. Add an automatic water refill mechanism. (Toilet float type.) This involves getting pressurized water to system vicinity.
  2. Implement automatic nutrient testing and dosing.


Thanks for reading!

A design for offset bicycle pedals

By Kurt Euler | Jul 7, 2016 | 0 Comments

From the Rube Goldberg department…

I recently wondered if a bicycle could be designed such that its pedals spent most of their time forward of their bearing, on the “power-stroke” side of the cycle.  Apart from any real or imagined utility of such a configuration, I thought it would be an interesting challenge to design the mechanics in Fusion 360. So, after several hours of jostling bodies, components, joints, planes, and sketches, I came up with this:


In the video, you can see that when one pedal is at the lowest position, the other isn’t at the top, but instead is positioned slightly forward, solidly in the power-stroke area.  The design achieves this by placing the axis of the pedal bearings behind the axis of the drive gear bearing (the drive gears pull the chain, not shown), then mechanically connecting the pedals to the drive gears by means of a few cogs and pegs. Note that while the angular position of each pedal is a function of the other, the degrees out-of-sync is variable, not 180 degrees, as is the case for standard bikes.

Two identically sized cogs are placed, one each, inside each pedal plane. They have a wide hollow bearing. The pedal bearings are inside the cog bearing, such that their axis of rotation of the pedals are behind that of the cogs. (Each pedal has its own bearing, although they share a common axis.) Each cog is propelled by a peg in its adjacent pedal, which extends into a slot in the cog, as shown here:

Pedal shaft and peg


A pinion gear on the frame keeps the two cogs in sync:

Pinion gear


The right cog is connected directly to the three drive gears, which share the same hollow bearing. These are otherwise the same gears as is used in a traditional bike gear system.

The video below shows how the pin in the left pedal shaft propels the left cog via the slot in the cog.


Use cases…

This contraption might very well solve a non-existing problem. I’d be interested in your thoughts. One group that could benefit are those with missing or weak lower legs, where starting from a dead start, or going up hill, could be challenging when one pedal is directly above another with a traditional gearing system.

Version 2.0 ideas…

  1. Reduce the size of the two cogs, or better…
  2. Move the pinion to inside the large bearing cavity, and reshape the cogs thus:

Teardrop gear


Footnote: This project was mainly for the purpose of “cutting my teeth” on the Fusion 360 CAD package. It involved a few restarts and backtracking, both from being a F360 newbie and from figuring out what would and not work mechanically in the design. It was worth the effort. I now have a much better “feel” for how to proceed with modeling, and at the same time have a list of questions and recommendations for Autodesk and the F360 Forum. If interested in accounts of my future tinkerings, I humbly invite you to subscribe to the blog in the right side bar of the Home Page. Thanks!

Hydroponics status update…

By Kurt Euler | Jun 24, 2016 | 0 Comments

Hydro_Frame_2016-06-24 About 1/2 way through the development of a A-Frame hydroponics system. For this project, I’m using Fusion 360 primarily for as-built documentation.








A shout-out for Autodesk’s user forums and “IdeaStation”

By Kurt Euler | Jun 13, 2016 | 0 Comments

Well, I’ve been offline for a while, tinkering, but thought I’d slip in a quick post in praise of the exemplary Fusion 360 user forums maintained in Autodesk’s Web site. I’m still an F360 newbie, but already my experience of the forums’ usefulness has vastly exceeded my expectations. I’ve found that within a day or two of posting a question, some expert user responds with an often exceedingly thorough explanation. For example, I recently posted a query in which I asked about the relationship of “models” and “forms” (t-splines) when they occur in the same design project. I received several very useful comments, including a long one that includes animation. Find that post in this thread. Very often, its an Autodesk employee who provides the answer.

Even more impressive is the degree to which the F360 group encourages ideas for future updates. The interface, shown here , presents a forum-like design, but cleverly asks other users to comment on each idea, and to vote on it also. Over time, Autodesk staff updates the status of the idea based on user interest, the product road map, etc. New entries are given a GATHERING SUPPORT status. As votes and comments are processed, an idea’s status can be updated to UNDER REVIEW, ACCEPTED, IMPLEMENTED, FUTURE CONSIDERATION, etc. If an idea is implemented, the contributing user is emailed a notification. How cool is that!?


Speaking of road maps, Fusion 360’s is shared, and commentable! Here’s their May 2016 roadmap update.


Even if your new to Fusion 360, the forums will serve you well!

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