Raspberrypi 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…

Your own Ruter.no realtime monitor

Mon, 23 May 2016 00:00:00 +0000

# Overview

By request, a quick how-to on setting up your own realtime monitor for ruter.no, Oslos public transit.

# As simple as possible

Get an old laptop
Set it to start a web browser at boot
Make the browser start to i.e. http://mon.ruter.no/monitor/3010314/Adamstuen/2190090

Done!

# Background

Ruter has an API, so you can go crazy and implement your own client easily, like I’ve done with rutercli. But there’s a much simpler solution. They’ve got a website in the same style as their public monitors, mon.ruter.no. You can start with the link above, and find the numbers and names you need from a normal ruter.no search. You’ll also find NSB stuff there. See ruter.no/reiseplanlegger/sanntid/egen-sanntidsskjerm for more info.

# In a white wooden frame

Here’s a basic example in a photo frame:

This one is run by a Raspberry Pi model B, but any model will do. The screen is from Chalk-elec, but any display will do. The frame is a normal photo frame. Then there’s some glue and plastics on the back to hold it all together.

To align two different transits use something like this HTML:

<!DOCTYPE html>
<html>
<head>
<TITLE>Info Screen</TITLE>
<meta http-equiv="refresh" content="6000">
<meta charset="utf-8">
</HEAD>
<body style="background-color:#2a2a2a" scroll="no">

  <iframe src="http://mon.ruter.no/monitor/2190090/Østerås [T-bane] (Bærum)?rows=4 " align="left" width=100% height=550 scrolling="no"  frameborder="0">
  </iframe>

  <iframe src="http://mon.ruter.no/monitor/2190090/Østerås [T-bane] (Bærum)?rows=4 " align="left" width=100% height=550 scrolling="no"  frameborder="0">
  </iframe>

</body>
</HTML>

And to have it start automatically at boot, edit /etc/xdg/lxsession/LXDE/autostart to look like this:

@xset s off
@xset -dpms
@xset s noblank
@unclutter

My crontab:

@daily /sbin/reboot
@reboot sleep 10; /root/browser.sh

And /root/browser.sh contains:

#!/bin/bash

killall midori
midori \
  --app=rutyr.html \
  --display=:0 \
  --execute Fullscreen

Cheap DIY babycam with night vision

Tue, 30 Sep 2014 00:00:00 +0000

# Overview

When I did this project in 2012 babycams cost from NOK 2000 and up, so I decided to see if I could build one using a Raspberry Pi, an IR light and a very cheap webcam.

This will of course only be a level 0 night vision (active).

# Parts

IR LEDs with a 12V PSU.
Raspberry Pi with a 5V PSU.
Webcam. I don’t have a link to it, but pretty much any webcam will do.

# Hardware setup

I set up a test and was disappointed that the IR setup hardly gave any visible picture at all, so I threw it in the trash. Then I rememberd that all digital cameras have an IR filter to sharpen daylight pictures. To remove it I did this:

Unscrew any lense or cover.
Look for a small, slightly colored piece of glass covering the CMOS chip, and remove it by force.
Reassemble.

Now the IR seemed to light up objects several meters away. As IR light can hurt eyes, I have the light pointed towards the ceiling, so only reflected light is ever hitting people.

# Software

Installed raspbian.
Installed motion.
Webcam is now available to local network for PCs (browser, VLC) and phones (VLC, video streaming apps).

# Result

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…