Difference between revisions of "User:Bertrik Sikken"

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You can reach me at bertrik@sikken.nl or bertrik@gmail.com
+
You can reach me at [mailto:bertrik@sikken.nl bertrik@sikken.nl] or [mailto:bertrik@gmail.com bertrik@gmail.com].
  
 
Studied Electrical Engineering at Twente University.
 
Studied Electrical Engineering at Twente University.
Line 11: Line 11:
  
 
Main interests:
 
Main interests:
* reverse-engineering things (USB stuff, mp3 players), working on http://rockbox.org
+
* reverse-engineering things (USB stuff, mp3 players), worked on http://rockbox.org (sansa clip players)
 
* studying bats and making electronics for recording/listening to bat sounds
 
* studying bats and making electronics for recording/listening to bat sounds
 
* radio stuff, in particular software-defined radio
 
* radio stuff, in particular software-defined radio
 
+
* energy-related stuff, visualisation
 +
* citizen science, particulate matter measurement, noise (future)
  
 
Projects I work(ed) on ([https://revspace.nl/index.php?title=User:Bertrik_Sikken&action=purge refresh]):
 
Projects I work(ed) on ([https://revspace.nl/index.php?title=User:Bertrik_Sikken&action=purge refresh]):
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== Project ideas ==
 
== Project ideas ==
 +
[[File:idea.jpg|right]]
 +
 
This is a list of ideas I'm thinking about, but have not fully developed into an actual project yet.
 
This is a list of ideas I'm thinking about, but have not fully developed into an actual project yet.
  
=== Understand Bluetooth AP ===
+
https://pine64.com/product/128mb-ox64-sbc-available-on-december-2-2022/
I'm trying to understand how to set up a bluetooth AP on a basic Linux system, such that you can connect to it using an Android phone or tablet.
+
 
 +
=== Stookalert ===
 +
Idee: gekleurd lampje dat aangeeft of er op dit moment een stookalert actief is
 +
 
 +
Implementatie:
 +
* kijk m.b.v. WiFi locatieservice in welke provincie je je bevindt
 +
* haal JSON op bij https://www.lml.rivm.nl/stookalert/stookalert.json
 +
* toon de bijbehorende kleur op het lampje
 +
 
 +
Resources:
 +
* Officiele pagina: https://www.atlasleefomgeving.nl/stookwijzer
 +
* Achterliggende JSON met toestand per provincie: https://www.lml.rivm.nl/stookalert/stookalert.json
 +
* Er moet ook nog ergens een API zijn die fijnmaziger aangeeft wat de toestand is ...
 +
 
 +
=== Display of current electricity usage ===
 +
I have a [https://www.zuidwijk.com/product/slimmelezer-plus/ slimme lezer] connected to the P1 port of my smart electricity meter.
 +
The default firmware exposes meter readings using an event stream (SSE) at http://slimmelezer.local/events
 +
 
 +
So for example, you can read this with curl:
 +
  curl http://slimmelezer.local/events
 +
With result:
 +
  event: state
 +
  data: {"id":"sensor-power_consumed_phase_1","value":0.046,"state":"0.046 kW"}
 +
 
 +
Specification of SSE: https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream
 +
 
 +
What I would like to do is to read these events and control a simple display to display  the current usage number.
 +
 
 +
=== Participating in ultrasonic sound project ===
 +
https://bat-migration-europe.netlify.app/project/
 +
 
 +
Use an audiomoth for this.
 +
 
 +
=== ESP32 C3 ===
 +
* [https://www.espressif.com/en/products/socs/esp32-c3 processor page]
 +
* [https://wiki.luatos.com/chips/esp32c3/index.html luatos basic esp32 c3 board]
 +
 
 +
=== Flexible LED ticker ===
 +
Ordered a flexible 32x8 RGB LED display:
 +
https://nl.aliexpress.com/item/4001296811800.html
 +
 
 +
Matching diffuser to be 3D printed:
 +
https://www.thingiverse.com/thing:1903744
 +
 
 +
=== Washing machine API ===
 +
https://tratt.net/laurie/blog/2023/displaying_my_washing_machines_remaining_time_with_curl_jq_pizauth.html
 +
 
 +
=== TinyML ===
 +
Investigate TinyML, see https://www.tinyml.org/
 +
Apparently can run on a RP2040 (raspi pi pico).
 +
 
 +
=== Bat box busy signal ===
 +
My brother built little pyramid 'blinkies': solar cell + Lithium-supercapacitor + harvesting circuit + LED encased in clear expoxy.
 +
 
 +
Can we add a low-power PIR sensor to this, and make a blinky that blinks if movement was detected by the PIR in the past hour?
 +
 
 +
=== Super tiny RFID ===
 +
See https://www.sparkfun.com/products/16464 an almost sand grain size RFID chip, 1.25mmx1.25mmx0.55mm
 +
 
 +
The accompanying reader "M6E Nano" is still quite expensive at $235.95 : https://www.sparkfun.com/products/14066
 +
 
 +
Uses the MuRata LXMSJZNCMF-198:
 +
"This product can be used as an ultra small tag and this can be
 +
fit on any metal objects, non-metal objects, as well as
 +
embedding into any objects by glue or adhesive and so on."
 +
 
 +
See also: ISO18000-63 and EPC global Gen2(v2)
 +
 
 +
Specification:
 +
* https://www.gs1.org/standards/rfid/uhf-air-interface-protocol
 +
 
 +
=== TheThingsNetwork-Sondehub bridge ===
 +
Uploads balloon telemetry to sondehub.
 +
 
 +
See https://github.com/bertrik/ttnhabbridge/issues/6
 +
 
 +
=== Actually smart boiler ===
 +
The boiler for hot water is about half of my electricity bill.
 +
The idea is to use/build a smart switch that switches it on at time when electricity prices are lowest.
 +
 
 +
Currently have a "Slimme boiler module" from Eneco, which is *not* actually smart,
 +
since it allows me no control whatsoever when it switches on (besides cutting the power in the meterkast).
 +
For example, it will switch on mid-day when my price is high and eneco's price is low, perhaps good for Eneco, not for me.
 +
Apparently, they even received a [https://nieuws.eneco.nl/slim-apparaatje-bij-boiler-vangt-pieken-wind--en-zonnestroom-op/ subsidy] for this.
 +
 
 +
A boiler is a pretty big load, about 3 kW, but it is not inductive.
 +
 
 +
Alternatives:
 +
* https://www.shelly.cloud/en-nl/products/product-overview/shelly-plus-1-pm-2-pack/shelly-plus-1-pm
 +
* https://www.solyxenergy.nl/solar-iboost/ to store excess solar energy in hot water, might also be useful for just controlling a boiler to use cheaper rates
 +
* tuya smartplug, like https://www.wifilampkoning.nl/merken-slimme-verlichting/tuya/tuya-enkele-smartplug-met-energiemeting ?
 +
* tuya 20A smart plug: https://nl.aliexpress.com/item/1005003347568206.html
 +
 
 +
=== Receiving gas meters ===
 +
Apparently gas meters send gas consumption data to the slimme meter using a wireless link in the 868 MHz band.
 +
Probably just FSK at 38.4, as mentioned here: https://a35.veron.nl/nieuwe-elektra-en-gasmeters/
 +
 
 +
Interesting leads:
 +
* https://github.com/stef/smeter
 +
* https://www.rtl-sdr.com/reading-household-wireless-utility-meters-with-an-rtl-sdr-and-plotting-the-data-in-home-automation-software/
 +
* https://github.com/bemasher/rtlamr
 +
 
 +
=== Multi-network wifi manager ===
 +
Figure out or create software so that ESP8266/ESP32 wifi manager can use multiple networks to connect (not just one),
 +
so it allowing storing credentials for more than one network. For example, the network at home, the hacker space, at work.
 +
Instead of reconfiguring the wifi manager for each network, you just *add* your credentials (and the existing credentials
 +
are not replaced).
 +
 
 +
See https://github.com/folkertvanheusden/M.A.X.X
 +
 
 +
Interesting candidates:
 +
* https://registry.platformio.org/libraries/martinverges/ESP32%20Wifi%20Manager wifi manager for ESP32, has a REST API for managing wifi network, but is incomplete in the sense that you need to write your own code (e.g. javascript) to actually *use* its API
 +
* https://github.com/arduino-libraries/Arduino_MultiWiFi is the arduino multi wifi library, to allow connecting to multiple different WiFi networks, but it is not a wifi manager, that starts a captive portal, etc
 +
 
 +
=== Automated bat counting ===
 +
Can we automatically count the number of bats from the image of a webcam mounted in a bat colony?
 +
Perhaps using some kind of AI or machine learning algorithm?
 +
 
 +
The image in question:
 +
https://stofradar.nl/coenecoop/
 +
 
 +
=== Use TheThingsIndoorGateway as Helium/ThingSix hotspot ===
 +
I have a spare TTIG that could perhaps be used as a Helium gateway, investigate what is possible.
 +
 
 +
One possiblity is to capture the gateway traffic from the TTN gateway events API, convert uplink data to a format that the Helium network understands and forward it.
 +
I don't really care about the Helium crypto tokens, this is just for fun and science.
 +
 
 +
What I definitely can do:
 +
* Capture data from the TTN gateway events API, convert it back to Semtech UP format and forward it somewhere to Helium (just not sure where!)
 +
* See also my https://github.com/bertrik/ttn-gateway-collector project which contains an initial implementation of TTN-to-UDP conversion
 +
 
 +
Showstoppers:
 +
* If you want to be a gateway on the Helium network, you have to *pay Helium*! Obviously I don't want that, I just want to share data to improve *their* network.
 +
 
 +
Open work:
 +
* Investigate if Helium has an open uplink API for their hotspots, if so study it etc, without paying the gateway fee
 +
* Investigate if Thingsix has an open uplink API for their hotspots, if so study it etc, without paying any gateway fee
 +
* Investigate if Thingsix is just another Helium, with weird crypto money
 +
 
 +
Interesting stuff:
 +
* https://docs.helium.com/use-the-network/setup-a-packet-forwarder unfortunately the link to setting up the 'light hotspot client' does not work!
 +
* https://docs.helium.com/mine-hnt/light-hotspots/
 +
* https://thingsix.com/
 +
 
 +
=== Adding BLE GATT interface to sensors ===
 +
The GATT specification allows measurement properties to be defined and transferred continuously over Bluetooth low-energy.
 +
 
 +
With GATT you can define a collection of properties (e.g. measurement items like temperature/humidity/particulate matter/noise, etc)
 +
organised in a simple structure of a BLE service.
 +
The 'notification' method allows you to basically push the data continuously to a connected host, e.g. a smart phone.
 +
 
 +
Services collects characteristic, a characteristic has values with units.
 +
Each of these (service, characteristic, unit) have their own unique "UUID".
 +
This is described in the so-called [https://btprodspecificationrefs.blob.core.windows.net/assigned-values/16-bit%20UUID%20Numbers%20Document.pdf 16-bit UUID numbers document]
 +
 
 +
Interesting stuff in GATT:
 +
* See GATT_Specification_Supplement_v5 paragraph 3.151, it has a noise characteristic with 1 dB resolution.
 +
* 0x27C3 is the GATT *unit* for sound pressure
 +
* 0x181A is the GATT environmental sensing *service*, document name "ESP_V1.0.0.pdf"
 +
* 0x2A6E is the GATT Characteristic and Object Type for temperature
 +
* 0x2A6F is the GATT Characteristic and Object Type for humidity
 +
* 0x2BD5 is the GATT Characteristic and Object Type for Particulate Matter - PM1 Concentration
 +
* 0x2BD6 is the GATT Characteristic and Object Type for Particulate Matter - PM2.5 Concentration
 +
* 0x2BD7 is the GATT Characteristic and Object Type for Particulate Matter - PM10 Concentration
 +
* Unfortunately I cannot find a characteristic for carbon-dioxide (CO2) in the BLE GATT unit document
 +
 
 +
See also https://programmaticponderings.com/2020/08/04/getting-started-with-bluetooth-low-energy-ble-and-generic-attribute-profile-gatt-specification-for-iot/
 +
 
 +
=== Reverse engineering XS-8217 bluetooth air quality meter ===
 +
This is a thing that measures CO2, humidity, temperature, TVOC and formaldehyde.
 +
 
 +
See also https://wiki.liutyi.info/display/CO2/ZN-2CO3+Inside
 +
 
 +
This teardown looks a lot like my sensor: https://www.youtube.com/watch?v=APnjhMrJChI
 +
Mine contains a "TPM-300A" sensor for measuring VOC.
 +
 
 +
It has a bluetooth interface, device name is XS-8217.
 +
It has a BLE GATT profile, with the following services
 +
* service 0xC760
 +
** characteristic 0xC762 (WRITE)
 +
** characteristic 0xC761 (NOTIFY)
 +
*** example data: 0x23 0x06 0x10 0x04 0xF1 0x00 0x23 0x65
 +
*** example data: 0x23 0x08 0x10 0x04 0x01 0x9A 0x00 0x0A 0x00 0x03 0x0E
 +
*** data shown on screen was approximately: CO2=418ppm, HCHO=0.003mg/m3, TVOC=0.013mg/m3, temp=24degC, humi=35%
 +
 
 +
So data in the characteristic 0xC761 seems to have a 4 byte constant header:
 +
* 0x23
 +
* length byte
 +
 
 +
Then we have for the first message: 0x10 0x04 0xF1 0x00 0x23 0x65
 +
* 0x10 0x04 fixed header
 +
* 0xF1 is temperature in 0.1 degree Celcius most likely (24.1)
 +
* 0x00 is ...
 +
* 0x23 is humidity most likely (35)
 +
* 0x65 is ... checksum perhaps
 +
 
 +
And for the second message: 0x10 0x04 0x01 0x9A 0x00 0x0A 0x00 0x03 0x0E
 +
* 0x10 0x04 fixed header
 +
* 0x01 0x9A is the CO2 concentration (410)
 +
* 0x00 0x0A is TVOC most likely (10)
 +
* 0x00 0x03 is HCHO most likely (3)
 +
* 0x0E is ... checksum perhaps
 +
 
 +
=== ribbon tweeter for bat audio ===
 +
Someone gave me this idea:
 +
Use a ribbon tweeter like this for playing back bat audio:
 +
<s>https://nl.aliexpress.com/item/4000973201791.html</s>
 +
https://nl.aliexpress.com/item/1005002565880660.html
 +
 
 +
The frequency spectrum shows no sign of dropping off at 20 kHz.
 +
 
 +
=== 3d glasses ===
 +
I got some 2nd hand 3d glasses, they look exactly like these ones:
 +
* GH-15 https://www.dhgate.com/product/g15-dlp-3d-active-shutter-glasses-96-144hz/213983026.html
 +
* Sintron https://www.amazon.de/Sintron-Kompatibel-TDG-BT500A-TDG-BT400A-Deutschland/dp/B015PCWMZ8
 +
The common name appears to be "G15-DLP".
 +
 
 +
A tear-down here:
 +
* https://blog.danman.eu/3d-shutter-glasses-teardown/
 +
 
 +
Interesting documents:
 +
* http://cmst.curtin.edu.au/wp-content/uploads/sites/4/2016/05/2012-28-woods-helliwell-cross-compatibility_of_shutter_glasses.pdf
 +
* http://cmst.curtin.edu.au/local/docs/pubs/2011-17-woods-helliwell-3D-Sync-IR.pdf
 +
 
 +
Someone claims he got something to work with some hacks:
 +
https://www.avsforum.com/threads/how-i-got-cheap-dlp-link-glasses-to-work-great.1887145/
 +
 
 +
=== Waterniveaumeter ===
 +
Op verschillende plekken in Gouda staat er water in de kruipruimte van huizen van bewoners.
 +
Kunnen we dat meten en inzichtelijk maken, voor bewoners, op een kaart bijvoorbeeld?
  
The idea is that there is some kind of useful application running on the Linux system, and that the "app" on the tablet/phone provides the user interface, connecting to the Linux system using REST.
+
Idee:
 +
* in de kruipruimte plaats je een module die waterhoogte kan meten
 +
* de module bestaat uit een microcontroller en een afstandsmeter, die de waterhoogte bepaalt
 +
* de gegevens worden via WiFi doorgestuurd naar een centraal punt, waar de data wordt verwerkt en gevisualiseerd
 +
* op een webpagina kan je een overzicht zien van alle meters die online zijn
 +
* de meting wordt gedaan door bijv. een laser-afstandsmeter of een ultrasoon-afstandsmeter
 +
* voeding? lastig, hoe krijg je 5v naar een potentieel natte plek?
 +
* kosten? verwachting < E 40,-
  
Possible useful links:
+
In Gouda wordt op veel verschillende plekken de grondwaterstand gemeten, zie https://opendata.munisense.net/portal/wareco-water2/group/581/Gouda-KJ38A , maar:
* https://www.linux.com/learn/weekend-project-personal-area-networking-bluetooth
+
* geen visualisatie op de kaart, je ziet alleen de meetlokaties d.m.v. een icoontje!
* <del>https://www.osnews.com/story/9836/Make_your_Arch_Linux_a_Bluetooth_Access_Point</del>: quite old, uses rfcomm, basically a serial port over bluetooth
+
* geen meetpunten in Gouda noord!
* <del>http://bluez.sourceforge.net/contrib/HOWTO-PAN</del>: describes setting up a network using the "pand" utility, can't find that utility
 
* [http://www.ampedrftech.com/cod.htm bluetooth device class calculator]
 
* http://blog.fraggod.net/2015/03/28/bluetooth-pan-network-setup-with-bluez-5x.html
 
* [https://github.com/mk-fg/fgtk/blob/master/bt-pan bt-pan] script as referred by the link above
 
* [https://www.linuxjournal.com/article/10915 Is Your Personal Area Network Giving You the BlueZ?]
 
  
My starting point is:
+
=== Online bat detector ===
* a Yocto based Linux distribution
+
Idea: use an ultrasonic microphone, connect it to a WebSDR, so people can tune into bat sounds remotely.
* a Linux 4.1 kernel
 
* Bluez 5
 
  
Understanding the various Linux drivers and tools in the Linux bluetooth stack
+
=== Raspberry pi airplane tracking ===
* btusb: the Linux kernel driver module for many USB/bluetooth adapters, 'modprobe'-ing this module also magically takes care of downloading firmware needed
+
Apparently now you can also participate in MLAT tracking of planes that don't transmit GPS coordinates themselves.
* hciconfig, low-level configuration utility for manipulating a bluetooth controller. A bit like ifconfig, it can bring the interface up or down, set options, etc.
 
* hcitool, yet another utility to perform low-level bluetooth operations, like querying the name of paired devices
 
* bluetoothd, the bluetooth daemon
 
** /etc/bluetooth/main.conf : supposedly (one of) the configuration files for bluetoothd
 
** bluetoothd can be accessed over DBUS apparently, see [https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc Bluez docs]
 
* bluetoothctl, a more high-level configuration utility, basically a command line user interface towards bluetoothd as I understand it.  
 
  
And some acronyms:
+
=== APRS gateway ===
* NAP: network access protocol
+
http://qso365.co.uk/2017/02/a-guide-to-setting-up-an-aprs-receive-only-igate-using-a-raspberry-pi-and-an-rtl-sdr-dongle/
* PAN: personal area network
 
* BNEP: bluetooth network encapsulation protocol
 
  
Getting somewhere: ?
+
=== JQ6500 ===
* <pre>dbus-send --system --type=method_call --print-reply --dest=org.bluez /org/bluez/hci0 org.bluez.NetworkServer1.Register string:'nap' string:'bnep' </pre>
+
Small inexpensive modules that play mp3 from an internal flash. Could be nice for a custom door bell for example.
* following this guide on the server-side (requires systemd): https://blind.guru/tag/bluetooth-pan.html#a-bluetooth-pan-access-point-with-systemd
 
  
=== investigate quadcopter remote control ===
+
More info at:
It turns out that the typical little cheap Chinese quadcopters use a remote-control protocol that can be easily recreated using the famous NRF24L01+ chip (< $1 and easily connected to an arduino).
+
* https://www.elecfreaks.com/wiki/index.php?title=JQ6500_Mini_MP3_Module
This gives nice opportunity to either:
+
* https://sparks.gogo.co.nz/jq6500/index.html
# transmit our own control signal, to control a quadcopter from something different than the manual remote control, e.g. automatic control
 
# receive the control signal, so the manual remote control that comes with a quadcopter can be used to steer other things (like a model car).
 
  
I haven't found a good overview of quadcopter remote control protocol specifications yet, there seem to be plenty examples of "here-is-the-code" however.
+
=== FPGA ===
 +
Cheap FPGA boards and nice applications:
 +
* https://bitbucket.org/appanp/artificial-neural-networks/wiki/Home/FPGAsAndNeuralNets.md#!sbcs-and-iot-boards
 +
* [http://nl.aliexpress.com/item/Altera-fpga-cycloneii-ep2c5t144-learning-board-development-board/872520721.html inexpensive ep2c5t144 board]
 +
* http://land-boards.com/blwiki/index.php?title=Cyclone_II_EP2C5_Mini_Dev_Board
 +
 
 +
=== Neural networks on low-end hardware ===
 +
Investigate if you can run a powerful neural network on relatively low-end/cheap/low-power hardware. For example a Raspberry pi.
 +
A RPI runs Linux, run python, just like some common neural frameworks.
 +
Do we need hardware acceleration from the GPU and does the RPI GPU support that?
 +
 
 +
Read list:
 +
* https://www.zdnet.com/pictures/raspberry-pi-meets-ai-the-projects-that-put-machine-learning-on-the-35-board/
 +
* https://www.pyimagesearch.com/2017/12/18/keras-deep-learning-raspberry-pi/
 +
* https://www.indiegogo.com/projects/sipeed-maix-the-world-first-risc-v-64-ai-module#/
 +
* https://ai.intel.com/intel-neural-compute-stick-2-smarter-faster-plug-and-play-ai-at-the-edge/
 +
 
 +
Bought a MaixPy:
 +
* see https://maixpy.sipeed.com/en/
 +
* see https://www.youtube.com/watch?v=KResVuAIMb4
 +
* see http://educ8s.tv/sipeed-m1-dock-review/
 +
* interesting? https://www.instructables.com/id/Transfer-Learning-With-Sipeed-MaiX-and-Arduino-IDE/
  
 
=== mini word clock in dutch ===
 
=== mini word clock in dutch ===
Line 81: Line 323:
 
See [https://plus.google.com/103276078656203197145/posts/7ki7rpJzk3a here for a demo] running on an arduino nano.
 
See [https://plus.google.com/103276078656203197145/posts/7ki7rpJzk3a here for a demo] running on an arduino nano.
  
The plan is to run this from an ESP8266 instead of an arduino nano, so it can get the time from the internet using NTP. The time offset will be fixed to Dutch local time, i.e. GMT+1 taking into account summer time. Summer time will be determined using the general rule "from 2:00 local time on the last sunday of March until 3:00 local time on the last sunday of October".
+
The plan is to run this from an ESP8266 instead of an arduino nano, so it can get the time from the internet using NTP.
 
+
Andreas Spiess demonstrated on youtube how existing libraries on the ESP8266 can be used to do the local time (including summer-time) calculations.
Local date calculation:
 
* http://stackoverflow.com/questions/5590429/calculating-daylight-saving-time-from-only-date
 
* https://github.com/niekproductions/word-clock
 
 
 
=== Understanding LoRa ===
 
Ultimate goal is to create an SDR algorithm to decode LoRa without the need for dedicated LoRa hardware. This could be useful when tracking HABs transmitting LoRa for example. See [[DecodingLora]] and [[EncodingLora]].
 
 
 
In particular, I should definitely check out [https://github.com/rpp0/gr-lora this gr-lora project].
 
Perhaps make it work for decoding balloon telemetry modes.
 
  
 
=== Cypress PSOC5 ===
 
=== Cypress PSOC5 ===
Line 104: Line 337:
  
 
See also https://github.com/jdesbonnet/RCWL-0516 for a reverse engineering effort of these doppler radar modules.
 
See also https://github.com/jdesbonnet/RCWL-0516 for a reverse engineering effort of these doppler radar modules.
 
=== Rust ===
 
Investigate the [https://www.rust-lang.org/en-US/ rust language].
 
 
=== ESP32 ===
 
I have a Wemos "LOLIN32 V1.0.0" ESP32 board, play with it. Discover Bluetooth capabilities, low power modes. Compare it with ESP8266.
 
* [https://github.com/wemos/arduino-esp32 ESP32 Arduino page] by Wemos
 
  
 
=== Bare-bones Arduino bat detector ===
 
=== Bare-bones Arduino bat detector ===
Line 136: Line 362:
 
Conversion takes 13 cycles, so this can be a problem to reach a sample rate above 80 kHz.
 
Conversion takes 13 cycles, so this can be a problem to reach a sample rate above 80 kHz.
  
==== Example C code ====
+
=== Indoor radar speed sign ===
(this is the general idea, but I don't know if it compiles):
+
This idea about placing a simple IQ-output radar sensor indoors in the hacker space, do some basic signal processing on the IQ doppler signal and determine movement speed and direction, then display this on a LED display.
<pre>
+
This is of no immediate practical use other than fun, but helps me to gain a bit more experience with microwave radar sensors and eventually build a more effective setup for detecting/counting bats flying in and out of a roost.
#define BUF_SIZE    16
 
 
 
static void ISR(void)
 
{
 
    static int16_t buffer[BUF_SIZE];
 
    static int16_t lowpass = 0;
 
    static int32_t sum = 0;
 
    static bool even = false;
 
 
 
    int16_t input, signal, mixed;
 
 
 
    // sample signal as 16 bits (10 bits significant)
 
    input = ....
 
 
 
    // HPF input signal
 
    signal = input - lowpass;
 
    lowpass += signal >> 4;
 
 
 
    // multiply by carrier
 
    mixed = even ? signal : -signal;
 
    even = !even;
 
 
 
    // calculate moving average sum
 
    sum += mixed ;
 
    sum -= buffer[index];
 
    buffer[index] = mixed ;
 
    index = (index + 1) % BUF_SIZE;
 
 
 
    // output LPF as 8-bit number
 
    out = sum >> 7;
 
    ...
 
}
 
</pre>
 
 
 
=== ADS-B multilateration ===
 
This idea is about determining position of aircraft that don't transmit GPS position themselves.
 
 
 
Many commercial aircraft transmit ADS-B/MODE-S signals containing all kinds of interesting information: aircraft id, altitude, flight number, speed, heading and position.
 
This way you can plot the trajectory of aircraft on a map and get an interesting view of the air traffic around.
 
The arrival of cheap software-defined-radios like the rtl-sdr made it possible for everyone to receive these signals.
 
 
 
Typically, small aircraft like single-engine air planes and helicopters do not transmit the position information, only the aircraft id, altitude and sometimes flight number.
 
Websites like flightradar24 receive information about these small aircraft from many different receivers, and can infer the position by multilateration.
 
Mulitlateration means that the position can be calculated from the relative delay that the ADS-B signal arrived at the different receiver stations (the radio signal moves at the speed of light!).
 
The required accurate time synchronisation needed for this can be calculated in a smart way from the ADS-B signals themselves.
 
 
 
As far as I know, there is no open-source implementation of this.
 
  
Stuff needed for this to work:
+
Implement this on a PSOC5 platform or on the STM32 using Arduino.
* receiver stations at diverse locations are needed, so you get a good 'constellation' receiving aircraft signals from many different angles
 
* each receiver station should be able to time-stamp the ADS-B signals it receives. It doesn't really matter if it is accurate in an absolute sense, just needs a certain time resolution.
 
** so we need a common convention on how/what to time-stamp ADS-B, take something that is present in each message, e.g. the exact instant that the first bit of the ICAO address is transmitted
 
* about time resolution: radio signals move at the speed of light; one sample at 2 Mbps sample rate is 0.5 microsecond, representing a distance of 150m.
 
* a central server receives all the ADS-B signals from the multiple receiver stations
 
** it matches up the same message from different receivers, knows where each receiver is, and performs the multilateration calculation
 
** it continually monitors the time offset of each receiver, by comparing timestamps from ADS-B message that DO contain GPS information
 
** since rtl-sdr receivers drift like crazy (up to 100 ppm), the server probably also needs to estimate the drift rate of each receiver. At 100ppm, a one second old timestamp could already be off by 100 us, or 30km!
 
* some kind of network protocol to get all the ADS-B data from each receiver to the central server
 

Latest revision as of 10:01, 3 January 2024

User info Bertrik Sikken
Name Bertrik Sikken
Nick bertrik
Tagline heb ik niet

You can reach me at bertrik@sikken.nl or bertrik@gmail.com.

Studied Electrical Engineering at Twente University.


Main interests:

  • reverse-engineering things (USB stuff, mp3 players), worked on http://rockbox.org (sansa clip players)
  • studying bats and making electronics for recording/listening to bat sounds
  • radio stuff, in particular software-defined radio
  • energy-related stuff, visualisation
  • citizen science, particulate matter measurement, noise (future)

Projects I work(ed) on (refresh):

 Project Status
FrontDoorDisplayAbandoned
HabAlertAppAbandoned
ISSOAbandoned
IbmPosDisplayAbandoned
Pico TrackersAbandoned
RadarOnAStickAbandoned
WifiLampAbandoned
A4PaperDispenserCompleted
BuildStatusTrafficLightCompleted
CJMCU-811Completed
CO2MeterHackingCompleted
CrawlSpaceSensorCompleted
DecodingLoraCompleted
DustSensorCompleted
ElectronicLoadCompleted
EspNowSkipCompleted
IntakefancontrollerCompleted
LichtKrantCompleted
LoRaGatewayCompleted
LoraBatBoxCompleted
LoraWanNodeCompleted
MHZ19Completed
MainsFrequencyCompleted
MiniSTM32F103ZECompleted
PowerLightCompleted
RC522HackingCompleted
RevRadioCompleted
STM32Completed
Secure iButtonCompleted
SoilHumiditySensorCompleted
StofAnanasCompleted
StofradarCompleted
TTNHABBridgeCompleted
VINDRIKTNINGCompleted
ZigbeeCoordinatorCompleted
Sensor-data-bridgeCompleted
AntiLostIn progress
AudioMothIn progress
CubeCellIn progress
EspAudioSensorIn progress
Esp32camIn progress
FMCWRadarIn progress
LoRa-E5-miniIn progress
LoraWanDustSensorIn progress
MainsFrequency2.0In progress
Msi2500SDRIn progress
Sim7020In progress
StereoBatRecorderIn progress
UltrasonicPlayerIn progress
EspNowAudioInitializing
... further results


Project ideas

Idea.jpg

This is a list of ideas I'm thinking about, but have not fully developed into an actual project yet.

https://pine64.com/product/128mb-ox64-sbc-available-on-december-2-2022/

Stookalert

Idee: gekleurd lampje dat aangeeft of er op dit moment een stookalert actief is

Implementatie:

Resources:

Display of current electricity usage

I have a slimme lezer connected to the P1 port of my smart electricity meter. The default firmware exposes meter readings using an event stream (SSE) at http://slimmelezer.local/events

So for example, you can read this with curl:

 curl http://slimmelezer.local/events

With result:

 event: state
 data: {"id":"sensor-power_consumed_phase_1","value":0.046,"state":"0.046 kW"}

Specification of SSE: https://html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream

What I would like to do is to read these events and control a simple display to display the current usage number.

Participating in ultrasonic sound project

https://bat-migration-europe.netlify.app/project/

Use an audiomoth for this.

ESP32 C3

Flexible LED ticker

Ordered a flexible 32x8 RGB LED display: https://nl.aliexpress.com/item/4001296811800.html

Matching diffuser to be 3D printed: https://www.thingiverse.com/thing:1903744

Washing machine API

https://tratt.net/laurie/blog/2023/displaying_my_washing_machines_remaining_time_with_curl_jq_pizauth.html

TinyML

Investigate TinyML, see https://www.tinyml.org/ Apparently can run on a RP2040 (raspi pi pico).

Bat box busy signal

My brother built little pyramid 'blinkies': solar cell + Lithium-supercapacitor + harvesting circuit + LED encased in clear expoxy.

Can we add a low-power PIR sensor to this, and make a blinky that blinks if movement was detected by the PIR in the past hour?

Super tiny RFID

See https://www.sparkfun.com/products/16464 an almost sand grain size RFID chip, 1.25mmx1.25mmx0.55mm

The accompanying reader "M6E Nano" is still quite expensive at $235.95 : https://www.sparkfun.com/products/14066

Uses the MuRata LXMSJZNCMF-198: "This product can be used as an ultra small tag and this can be fit on any metal objects, non-metal objects, as well as embedding into any objects by glue or adhesive and so on."

See also: ISO18000-63 and EPC global Gen2(v2)

Specification:

TheThingsNetwork-Sondehub bridge

Uploads balloon telemetry to sondehub.

See https://github.com/bertrik/ttnhabbridge/issues/6

Actually smart boiler

The boiler for hot water is about half of my electricity bill. The idea is to use/build a smart switch that switches it on at time when electricity prices are lowest.

Currently have a "Slimme boiler module" from Eneco, which is *not* actually smart, since it allows me no control whatsoever when it switches on (besides cutting the power in the meterkast). For example, it will switch on mid-day when my price is high and eneco's price is low, perhaps good for Eneco, not for me. Apparently, they even received a subsidy for this.

A boiler is a pretty big load, about 3 kW, but it is not inductive.

Alternatives:

Receiving gas meters

Apparently gas meters send gas consumption data to the slimme meter using a wireless link in the 868 MHz band. Probably just FSK at 38.4, as mentioned here: https://a35.veron.nl/nieuwe-elektra-en-gasmeters/

Interesting leads:

Multi-network wifi manager

Figure out or create software so that ESP8266/ESP32 wifi manager can use multiple networks to connect (not just one), so it allowing storing credentials for more than one network. For example, the network at home, the hacker space, at work. Instead of reconfiguring the wifi manager for each network, you just *add* your credentials (and the existing credentials are not replaced).

See https://github.com/folkertvanheusden/M.A.X.X

Interesting candidates:

Automated bat counting

Can we automatically count the number of bats from the image of a webcam mounted in a bat colony? Perhaps using some kind of AI or machine learning algorithm?

The image in question: https://stofradar.nl/coenecoop/

Use TheThingsIndoorGateway as Helium/ThingSix hotspot

I have a spare TTIG that could perhaps be used as a Helium gateway, investigate what is possible.

One possiblity is to capture the gateway traffic from the TTN gateway events API, convert uplink data to a format that the Helium network understands and forward it. I don't really care about the Helium crypto tokens, this is just for fun and science.

What I definitely can do:

  • Capture data from the TTN gateway events API, convert it back to Semtech UP format and forward it somewhere to Helium (just not sure where!)
  • See also my https://github.com/bertrik/ttn-gateway-collector project which contains an initial implementation of TTN-to-UDP conversion

Showstoppers:

  • If you want to be a gateway on the Helium network, you have to *pay Helium*! Obviously I don't want that, I just want to share data to improve *their* network.

Open work:

  • Investigate if Helium has an open uplink API for their hotspots, if so study it etc, without paying the gateway fee
  • Investigate if Thingsix has an open uplink API for their hotspots, if so study it etc, without paying any gateway fee
  • Investigate if Thingsix is just another Helium, with weird crypto money

Interesting stuff:

Adding BLE GATT interface to sensors

The GATT specification allows measurement properties to be defined and transferred continuously over Bluetooth low-energy.

With GATT you can define a collection of properties (e.g. measurement items like temperature/humidity/particulate matter/noise, etc) organised in a simple structure of a BLE service. The 'notification' method allows you to basically push the data continuously to a connected host, e.g. a smart phone.

Services collects characteristic, a characteristic has values with units. Each of these (service, characteristic, unit) have their own unique "UUID". This is described in the so-called 16-bit UUID numbers document

Interesting stuff in GATT:

  • See GATT_Specification_Supplement_v5 paragraph 3.151, it has a noise characteristic with 1 dB resolution.
  • 0x27C3 is the GATT *unit* for sound pressure
  • 0x181A is the GATT environmental sensing *service*, document name "ESP_V1.0.0.pdf"
  • 0x2A6E is the GATT Characteristic and Object Type for temperature
  • 0x2A6F is the GATT Characteristic and Object Type for humidity
  • 0x2BD5 is the GATT Characteristic and Object Type for Particulate Matter - PM1 Concentration
  • 0x2BD6 is the GATT Characteristic and Object Type for Particulate Matter - PM2.5 Concentration
  • 0x2BD7 is the GATT Characteristic and Object Type for Particulate Matter - PM10 Concentration
  • Unfortunately I cannot find a characteristic for carbon-dioxide (CO2) in the BLE GATT unit document

See also https://programmaticponderings.com/2020/08/04/getting-started-with-bluetooth-low-energy-ble-and-generic-attribute-profile-gatt-specification-for-iot/

Reverse engineering XS-8217 bluetooth air quality meter

This is a thing that measures CO2, humidity, temperature, TVOC and formaldehyde.

See also https://wiki.liutyi.info/display/CO2/ZN-2CO3+Inside

This teardown looks a lot like my sensor: https://www.youtube.com/watch?v=APnjhMrJChI Mine contains a "TPM-300A" sensor for measuring VOC.

It has a bluetooth interface, device name is XS-8217. It has a BLE GATT profile, with the following services

  • service 0xC760
    • characteristic 0xC762 (WRITE)
    • characteristic 0xC761 (NOTIFY)
      • example data: 0x23 0x06 0x10 0x04 0xF1 0x00 0x23 0x65
      • example data: 0x23 0x08 0x10 0x04 0x01 0x9A 0x00 0x0A 0x00 0x03 0x0E
      • data shown on screen was approximately: CO2=418ppm, HCHO=0.003mg/m3, TVOC=0.013mg/m3, temp=24degC, humi=35%

So data in the characteristic 0xC761 seems to have a 4 byte constant header:

  • 0x23
  • length byte

Then we have for the first message: 0x10 0x04 0xF1 0x00 0x23 0x65

  • 0x10 0x04 fixed header
  • 0xF1 is temperature in 0.1 degree Celcius most likely (24.1)
  • 0x00 is ...
  • 0x23 is humidity most likely (35)
  • 0x65 is ... checksum perhaps

And for the second message: 0x10 0x04 0x01 0x9A 0x00 0x0A 0x00 0x03 0x0E

  • 0x10 0x04 fixed header
  • 0x01 0x9A is the CO2 concentration (410)
  • 0x00 0x0A is TVOC most likely (10)
  • 0x00 0x03 is HCHO most likely (3)
  • 0x0E is ... checksum perhaps

ribbon tweeter for bat audio

Someone gave me this idea: Use a ribbon tweeter like this for playing back bat audio: https://nl.aliexpress.com/item/4000973201791.html https://nl.aliexpress.com/item/1005002565880660.html

The frequency spectrum shows no sign of dropping off at 20 kHz.

3d glasses

I got some 2nd hand 3d glasses, they look exactly like these ones:

The common name appears to be "G15-DLP".

A tear-down here:

Interesting documents:

Someone claims he got something to work with some hacks: https://www.avsforum.com/threads/how-i-got-cheap-dlp-link-glasses-to-work-great.1887145/

Waterniveaumeter

Op verschillende plekken in Gouda staat er water in de kruipruimte van huizen van bewoners. Kunnen we dat meten en inzichtelijk maken, voor bewoners, op een kaart bijvoorbeeld?

Idee:

  • in de kruipruimte plaats je een module die waterhoogte kan meten
  • de module bestaat uit een microcontroller en een afstandsmeter, die de waterhoogte bepaalt
  • de gegevens worden via WiFi doorgestuurd naar een centraal punt, waar de data wordt verwerkt en gevisualiseerd
  • op een webpagina kan je een overzicht zien van alle meters die online zijn
  • de meting wordt gedaan door bijv. een laser-afstandsmeter of een ultrasoon-afstandsmeter
  • voeding? lastig, hoe krijg je 5v naar een potentieel natte plek?
  • kosten? verwachting < E 40,-

In Gouda wordt op veel verschillende plekken de grondwaterstand gemeten, zie https://opendata.munisense.net/portal/wareco-water2/group/581/Gouda-KJ38A , maar:

  • geen visualisatie op de kaart, je ziet alleen de meetlokaties d.m.v. een icoontje!
  • geen meetpunten in Gouda noord!

Online bat detector

Idea: use an ultrasonic microphone, connect it to a WebSDR, so people can tune into bat sounds remotely.

Raspberry pi airplane tracking

Apparently now you can also participate in MLAT tracking of planes that don't transmit GPS coordinates themselves.

APRS gateway

http://qso365.co.uk/2017/02/a-guide-to-setting-up-an-aprs-receive-only-igate-using-a-raspberry-pi-and-an-rtl-sdr-dongle/

JQ6500

Small inexpensive modules that play mp3 from an internal flash. Could be nice for a custom door bell for example.

More info at:

FPGA

Cheap FPGA boards and nice applications:

Neural networks on low-end hardware

Investigate if you can run a powerful neural network on relatively low-end/cheap/low-power hardware. For example a Raspberry pi. A RPI runs Linux, run python, just like some common neural frameworks. Do we need hardware acceleration from the GPU and does the RPI GPU support that?

Read list:

Bought a MaixPy:

mini word clock in dutch

Basically an monochrome 8x8 word clock, in Dutch, showing local time in the Netherlands.

This git repo has the current code.

See here for a demo running on an arduino nano.

The plan is to run this from an ESP8266 instead of an arduino nano, so it can get the time from the internet using NTP. Andreas Spiess demonstrated on youtube how existing libraries on the ESP8266 can be used to do the local time (including summer-time) calculations.

Cypress PSOC5

Play with the Cypress PSOC5 platform, which combines a ARM Cortex-m3 processor with configurable analog blocks. I'm thinking of combining it with a 24 GHz doppler radar sensor, to process the signal and present it as a USB audio device (stereo signal contains I and Q parts). See RadarOnAStick.

Simple Doppler motion sensors

You can find basic doppler microwave motion sensors based on a single transistor, with some weird traces on the PCB very cheaply, for example

Typically the microwave part of these consists of a single transistor with a rectangular area on one leg and a meandering trace (with lots of vias to the other side) on the other leg. The output of this circuit seems to go into a chip very much like the ones used in PIR sensors.

See also https://github.com/jdesbonnet/RCWL-0516 for a reverse engineering effort of these doppler radar modules.

Bare-bones Arduino bat detector

This is an idea for a very basic heterodyne bat detector, doing signal processing on an Arduino, requiring minimal external components.

The basic principle of a heterodyne detector is that it just mixes (multiplies) the audio signal with a square wave, low-pass filters the result and puts it on a speaker.

Multiplying with a square wave can also be considered to be just alternatively inverting and not-inverting the signal. So if you sample an ultrasonic signal at twice the rate you want to multiply, you can just subtract odd samples from even samples and low-pass filter that.

How this can be done in an AVR Arduino:

  • sample the audio signal at twice the detection frequency, say 84 kHz. An AVR should just be able to do that.
  • apply a 1-pole IIR high-pass filter to remove DC bias, this takes one shift instruction and one addition.
  • multiply by the detection frequency, this means just inverting the odd samples.
  • low-pass filter the signal, this can be done using a moving average filter, say 16 samples long (first null at 5.25 kHz). Theoretically, averaging 16 samples should result in two bits extra accuracy. This operation takes some storage, an addition and a subtraction.
  • output the filtered signal using PWM, possibly at the same rate that we are sampling the input audio.

The microphone can be a 40 kHz piezo transducer, to keep it cheap (but also limited to 40 kHz). The pre-amplifier can be a single transistor with some resistors around it, providing about 40x gain. The arduino does the signal processing (mixing, low-pass filter) to shift the bat audio to human range. The speaker amplifier can just be a simple two transistor push-pull circuit, since the output from the Arduino is digital/PWM.

AVR Arduino sample rate

As far as I understand, the ADC clock can be set to 1 MHz. Conversion takes 13 cycles, so this can be a problem to reach a sample rate above 80 kHz.

Indoor radar speed sign

This idea about placing a simple IQ-output radar sensor indoors in the hacker space, do some basic signal processing on the IQ doppler signal and determine movement speed and direction, then display this on a LED display. This is of no immediate practical use other than fun, but helps me to gain a bit more experience with microwave radar sensors and eventually build a more effective setup for detecting/counting bats flying in and out of a roost.

Implement this on a PSOC5 platform or on the STM32 using Arduino.