Projects on falkp.no/blog

Ninjabox

Fri, 23 Nov 2018 00:00:00 +0000

# Overview

Untrickable laser alarm, with an easy-to-knock-out fusebox.

A tribute to (the alarms in) Mark of the Ninja.

# Background

In the game you have to sneak into buildings with high tech alarms. Some of the laser traps can be deactivated by knocking out the fuse box with a dart.

So I made a laser alarm with a fusebox that can be knocked out. This is mainly to keep kids occupied, and motivated to practice throwing.

# Features

Glowing ⚡ with simple animations and color changes (start-up, alarm, sparks)
Laser triggered alarm, which can’t be fooled by using a separate laser or flash light. This is done by pulsing the laser and making sure photo resistor is relatively dark when laser is off.
Motion activated “play dead” (throw somehting on the fuse box, and it will black out for 10 seconds).
Play sounds for alarm, sparks, start-up

# Demo

Knocking out the alarm (~3MB).

Attempting to fool the alarm (~2MB).

Not shown here: speaker and tiltsensor.

See gitlab for build instructions and code.

Car-logger - part 3

Fri, 25 May 2018 00:00:00 +0000

# Overview

A self-hosted, real-time, inexpensive open source car tracker built with Raspberry Pi Zero W, Nextcloud, and optionally Home Assistant.

I’ve had a few earlier tries at car position logging, read those first if you’re interested: Car logger 2.

# Background

Goal: logging and sharing location of my non-connected car, for practicality and fun.

Earlier tries was using a phone, but that had problems. No Android phone will switch back on if it runs out of power without manual intervention.

# Prerequisites

I needed power from the car, but want it to cut off when the ignition is off. My 12 V outlets didn’t. So I used a fuse holder with outlet to accomplish this. To that I attached a 12 to 5 V converter.

Also I chose to go without any battery or UPS, so the Pi has to deal with unclean shutdown every time. For this I run the SD card read-only using rpi-readonly.

# Hardware

I had little experience with Arduino at the time of start, but lots with Pi, so I used a Pi Zero. Mainly for it’s low power consumption.

I first tried Diymall-G-mouse-Glonass GPS dongle, but reception was very bad, so switched to BN-808-USB-GPS.

For uplink I used a cheap 3G USB modem Tolkien-Portable and a data-twin SIM card.

# Backend

I started writing a backend in 2014, BigBrotherGPSweb, but didn’t get very far. Fortunately someone has filled my need. Nextcloud, a self-hosted dropbox alternative, has a plugin called PhoneTrack. It has nice features like public sharing, users, filters, etc. and use Openstreetmap. SSL for transport encryption.

For home automation I use Home Assistant, so I also wanted the data there as well.

Map in Nextcloud/PhoneTrack:

Status in Home Assistant:

# Software

I found no premade solution to use wifi triangulation in python, so I wrote wifindme (available from pip, python 2 and 3). It can use Mozilla, radiocells.org or, with small changes, Google. Use what has best coverage where you need it.

For the actual reporting I wrote LocationReporter. It can use wifi triangulation, GPS or both. It will use wifi while the GPS is warming up, and when GPS fails. The results can be sent to both my backends.

# Build

I’ve not yet created any kind of case. The tracker lives in a card board box in my car door.

# Problems

PhoneTrack could be easier to use on a phone.

# Improvements

The setup should be moved to the trunk, out of sight.
I really should get a case and mount the parts properly.
The Pi Zero has bluetooth, so I could fetch data from OBD and upload it. Unfortunately my cars OBD doesn’t supply very interesting info (no battery voltage, fuel consumption, fuel status).
Should be enough to send data to either Nextcloud or Home Assistant, not both.
A switch for private mode or you-don’t-have-to-post-every-ten-seconds mode could be nice.
Radiocells.org let’s you download the data set for local use. Local wifi lookup is very fast, so this would make wifi triangulation faster, and less data used and leaked.

# Conclusions

I’m happy with the results. It’s been running for months now without problems. And it’s good sharing our position real-time on long drives.

Volumio based radio with NFC

Tue, 19 Dec 2017 00:00:00 +0000

# Overview

Volumio based internet radio, controlled by NFC, built in an old speaker.

# Background

Inspired by the extreemly good looking Spotify Box and QR based systems like Audiosphere, I wanted to make something similar for my kids. I’ve earlier built a few radios based on small, cheap bluetooth speakers like music angel, but wanted something with better sound this time.

# Prototype

QR are fast and cheap, so I made a quick prototype. It turned out they are unreliable when there’s no display to give feedback on how the camera sees them. Both lighting and focus was a problem.

Next up, NFC. I decided on a PN532 NFC reader, simply because I had one around. They’re about $8 / 70 NOK on ebay. It communicates via i2c, and there’s a python library for it. I decided to make it easy for myself and allow for any kind of NFC tag I could get hold of, so the plan was to read and use what ever data or ID the tags contain, and make a list to match IDs and URLs.

# Volumio

Volumio is a general music player for small devices like the Pi. Due to Mopidy it supports playing music from lots of sources. The two I’m interessted in are internet radios and Spotify, but this will work for anything Mopidy can play.

Volumio also has plugins for other stuff, like mono output, being a Spotify Connect speaker and button controls connected via GPIO like I will use here.

# Setup

As mentioned in the readme, there are a few steps to install NFC support. You have to enable SSH first. Then install packages, check that the i2c connection to the reader is working, enable services.

Reading a tag looks like this:

$ ./readnfc.py
Reading tag list readnfc.list
6 tags in store. Ready to read.
Card data: bytearray(b'K\x01\x01\x00D\x00\x07\x04!T\xcao?\x81') / 4b010100440007042154ca6f3f81
Stoping any music currently playing
Play audio feedback.
webradio http://nrk-mms-live.telenorcdn.net:80/nrk_radio_alltid_nyheter_aac_h
Play selected source webradio http://nrk-mms-live.telenorcdn.net:80/nrk_radio_alltid_nyheter_aac_h

Then you add that tag to your list, readnfc.list, in the same directory. There are lots of examples for radios and spotify playlists in it already. Restart the service and you should be done.

See demo video (~4MB).

# Hardware

For sound I connected a cheap USB soundcard (first hit on ebay), via a ground loop filter to a Class D amplifier, to the terminals of the speaker.

A 1k potmeter for volume, and two push-buttons for play/pause and next.

# Tags

Any tags works, but they need to look attractive, so I created some business card sized pictures to hold them.

RadiOS part 2

Wed, 17 Aug 2016 00:00:00 +0000

# Overview

See RadiOS part 1.

So I started making a prototype to figure out if I could “sense” both selections with GPIO pins, while the designer started modeling and rendering suggestions for the physical design. The solution chosen was to first set all volume control pins to high, and check which channel control points registered as on, then reverse (control points high, check volumes).

# Sound

For sound we tore down a Music Angel portable speaker. It gave us two speakers, an amplifier running on 5V and a battery which we threw away. The built in soundcard gave horrible sound under certain conditions, so a cheap USB soundcard was used instead.

# Case

We wanted to try both a 3D-printed version and a CNC’ed one. A print at Shapeways would cost us ~$200, plus shiping and tax. We got one printed localy for ~$80. It’s has yet to be used. A local CNC person wanted ~$270. The case we’ve used in the final build is hand made of wood.

## Plastic case

## Renderings of other variations

# Prototype

# Build 1

We chose to paint the front in black board paint, to allow easy change of channel labels and a personal touch.

Other builds may have a white board front, or be something very different.

# Conclution so far

It’s an interessting UI, and people want to touch it. However programming the channels and first time setup is hard. Also the Pi or musicbox is very slow to start streaming. This kind of breaks the fun of it.

To be continued…

Car-logger - part 2

Mon, 29 Sep 2014 00:00:00 +0000

# Overview

Read part one of Car-logger first, if you haven’t.

I chose to go with outdated Android phones in the previous article. Phones with CyanogenMod and no Google Play. This means that they run all free software, except for some firmware blobs and drivers. No background services driving up data or battery usage, no third party tracking my location.

I tried out Traccar. The app worked fine, but the backend was a big, horrible java thing. Poor UI, overkill for my purpose, and too much for me to get hacking on.

After trying out a few different ones I finally found BigBrotherGPS. It was half of what I wanted. An app that simply makes a http request with a few parameters in post-data. The backend wasn’t more than a proof-of-concept, but http requests are easy to work with and language agnostic.

So I created BigBrotherGPSweb (a better name is needed). See github for a proper description, but the basics are:

Receive http/https requests.
Store requests and devices in mysql.
Display results in a map.

It still need some work, and I’ll be working on it until I get bored or find a new project. But it currently serves the purpose.

And of course it can be used to track more than cars.

# Edit 20140930

This requires a SIM card. My operator supplies a twin SIM for NOK 20 / month, so it’s a low cost for me.

# Pics, or it didn’t happen!

RadiOS part 1

Fri, 09 May 2014 00:00:00 +0000

# Overview

In my opinion most radios, especially internet radios, have horrible interfaces. Small buttons, small displays, often touch, often several functions for each button.

So Erik and I set out to design a new, better radio for ourselves. Our main requirements were ease of use and a very physical UI. Something you’d want to touch and play with.

# Platform

The Raspberry Pi is our platform of choice at the moment, so we have some physical restrictions and long boot time.

# Physical designs

## The cone

Our first idea was a cone that would rotate for volume and press down for on, next channel, off. A very basic look, and extreamly easy to use. What killed this was the size it would need to be to accomodate an rPi and the mechanical complexity of making the twist and click switch.

## Brainstorming

So we hit the whiteboard. Some of the designs from our brainstorming:

A vertical rod with the radio sliding up/down for volume.
A body-like shape hanging from the wall.
A horizontal rod, where you pick up the radio and hang it on the position of the channel you want.
Magnets! Anything with magnets!

## The chosen design

Inspired by the switch boards of early phone systems, we chose to make rows of connections where you’d short two rows to make two selections at once. One row for the channels, one for the volumes.

We went with magnets instead of jacks to make it look more modern and be quick to use.

## Software

Netradio functionality can be solved in so many ways on the command line. From the most basic:

cvlc url / aplay url / mplayer url

The medium:

Music Player Daemon

The advanced:

Musicbox

The latter one is a brilliant use of the rPi. In short it includes out of the box support for Spotify, Google Music, Last.fm, internet radio, SoundCloud, local files, files from network shares. Controlled by a webUI or any existing MPD app.

We chose Musicbox.

To be continued…

Car-logger - part 1

Tue, 22 Apr 2014 00:00:00 +0000

# Overview

I want to know where my car is. Especially if it gets stolen. Logs would be a bonus. Also, I have several outdated Android phones, which has all necessary hardware.

I don’t want to use Google (latitude) or other service providers (embedded hardware).
I don’t want to pay, unless I have to.
If possible, I’d like it to do more (explained further down).

# Hardware options

## Old android phones

Pros:

Free hardware.
Lots of sensors (GPS, compass, barometer, temperature of hardware/battery, WiFi, Bluetooth, camera, microphone).
UPS (the battery).
Low power consumption.
Reasonably small.
Can be used for calling in an emergency.

Cons:

Not as easily programmed as something running a full Linux.
Lots of apps doesn’t run on old versions of Android.

## Raspberry Pi (or similar)

Pros:

Easy to program.
Easily hook up extra gear via USB.
Can get online for free by connecting to any open network. Or even start cracking passwords.

Cons:

Cost (the Pi isn’t expensive, but with full set of attachments it may be.
Size/cable-mess.
No RTC (real-time-clock). Need network to set time after a reboot.
Power consumption.
UPS is expensive.

## Dedicated GPS logger

Like this one: Mini GSM tracker.

Pros:

Size.
Ease of use.
Battery time.

Cons:

All data is sent to an unknown company in China.
No expandability, programability.
SIM card is needed, twin SIM can not be used as calls will trigger a location report by SMS to caller.

## Conclusion

I think the phones easily wins this one for me.

# Extra features

Extra features I’d like, once I’ve decided to go with phones:

Run scanning for Open WLAN Map and/or Mozilla.
Run reporting for PressureNET if possible.
Have phone attempt to connect to open WiFis, instead of needing a SIM-card.

To be continued…

photOS 2.0 - a better photo frame

Mon, 17 Feb 2014 00:00:00 +0000

# Overview

This is about improving photOS, mentioned in http://0p.no/2014/02/14/photos1.html.

When building this, price wasn’t a factor. If you want something cheap, you can still use this software with an old laptop or other recycled hardware.

The display from Chalkboard Electronics is beautiful. Good resolution (not extreme resolution, though), good contrast, nice colors. And it supplies power for the RPi. Unfortunately it’s hard to attach stuff to it. There are nothing but smooth surfaces.

All taped up to hide backlight. What you see is a rpi, a 4-port usb hub, a thumb drive (for keeping photos on) and the power board for the display.

Using some cardboard to keep everything together. Also makes for a decent foot.

Done and placed on the table. The photo doesn’t do the screen justice.

# Hardware

Raspberry Pi
10" Touch screen
Cover made of cardboard and tape.

# Software

photOS

# Features

Sync files from ownCloud, a free, selfhosted alternative to Dropbox.
Display local images in a slideshow.
Display images from web. I.e. webcams, weather reports, RSS feeds.
Display images from reddit, i.e. lates from r/newsporn, r/wallpapers, etc.
Stream video, i.e. from baby monitor, live webcams.
Display websites, i.e. news.
Display recent images (from ownCloud), by looking at date in Exif.
Turn off LCD at night.

Here is my current crontab, to show how I’m using it:

MAILTO=****
# m h  dom mon dow   command

PHOTOS=/home/pi/photOS

#Sync owncloud
#27 7-18 * * *  ${PHOTOS}/helpers/sync-owncloud.sh

#Morning
0 6 * * *       ${PHOTOS}/helpers/powersave.sh 1; ${PHOTOS}/web/weather.sh
0 7    * * *    ${PHOTOS}/web/website.sh "http://nrk.no/tekst-tv/100/"

#Normal photo display
0  9-16 * * *   ${PHOTOS}/helpers/kill.sh; ${PHOTOS}/photos/slideshow.sh

#Display weird images from the net
0 17 * * *      ${PHOTOS}/helpers/kill.sh; ${PHOTOS}/photos/slideshow.sh $( ${PHOTOS}/web/rss-images.sh 50 )

#Baby monitor streaming
0 19,21 * * *   ${PHOTOS}/helpers/kill.sh; $PHOTOS/streams/cvlc.sh http://192.168.1.84:8081

#Night
0 1 * * *       ${PHOTOS}/helpers/powersave.sh 0; ${PHOTOS}/helpers/kill.sh;

# Challenges

The screen has no attachments. I’ve currently just taped the RPi to the back, which works but isn’t very beautiful and will break down. See “Plans”.
LXDE, the default window manager on Raspbian, has no multitouch support. The image viewer, feh, has no gesture support. I’ve looked at a few ways to use touch, but hasn’t decided on anything yet. See this Reddit post.
Feh is somewhat lacking in rotating photos correctly.

# Plans

Use touch capabilities.
3d printed or CNCed enclosure.
Display photos related to this date. I.e. if christmas, display photos from past christmases.
Look for better image viewer.