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Bertrik Sikken
Works at Technolution
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Bertrik Sikken

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Ordered a set of these 5.8 GHz motion sensors: https://nl.aliexpress.com/item/5-8GHZ-Microwave-Radar-Module-Smart-Sensoring-Switch-6-9M-Home-Control/32602485648.html

Apparently they work quite well: http://tech.scargill.net/microwave-radar/

I wonder how they really work. I guess Q1 might be the active component. Free space wavelength at 5.8 GHz is about 52 mm. Perhaps the squiggly line with the vias (?) in it is some kind of resonating structure? Or maybe the green area left of the X has some function to tune it?

These ones just give a digital output apparently which goes active for a bit when movement is detected. I wonder if you can also get at some analog doppler frequency difference signal somehow, like with the HB-100 type sensors.
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I received the units this week and tried them out today. I changed the activation time from 30 seconds to 1 second by soldering a 1k resistor in location R6. This makes them easier to test. They do work, but do not seem to be that sensitive at their default setting, but I think I can adjust that too.
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Bertrik Sikken

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Did some LoRa "wardriving" in Gouda this weekend, mapping the received signal strength of LoRa node that I took with me on my bicycle. The image shows the signal strength for one particular gateway to the east of Gouda city center.
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Bertrik Sikken

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I'm working on a simple standalone location tracker based on wifi access points detected by an inexpensive WiFi-capable microcontroller (the ESP8266): https://revspace.nl/EspWifiTracker

The image below shows a bunch of locations calculated by the google location service based on the WiFi access points detected by my tracker during a little trip through Gouda this afternoon.

Instead of icons, I'd like to draw circles with the radius corresponding to the "accuracy" field returned by the google location service. I don't know yet how to do this in QGIS.

Silly problem: I only got 25 points because the USB power bank I used to power the tracker shuts itself off when it doesn't detect enough current being drawn when I put the ESP8266 in deep sleep mode to save power ... :)
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This is very neat indeed.
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Bertrik Sikken

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My new motto for git use: "if you branch it, you merge it!"
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Why? Trees don't do it, why would you? ;)
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Bertrik Sikken

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My project page about understanding the LoRa RF modulation format was mentioned on hackaday this weekend!

See:
http://hackaday.com/2016/01/31/hacking-the-internet-of-things-decoding-lora/

LoRa is a spread-spectrum radio modulation format that, combined with forward error coding, allows for low-power communication with larger range, for example for "internet-of-things" devices.
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Congrats!
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Bertrik Sikken

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Hi all,

I'm following a series of Linux kernel driver programming workshops with a strong focus on Allwinner/sunxi boards at my local hackerspace: https://revspace.nl/KernelDriverProgrammingCourse2015

So far, we've been testing / adding support for existing stuff (like OTG) for Allwinner devices by extending device tree files for various boards. We're also working on adding official support for i2c devices like touchscreen controllers and accelerometers.
My contribution will be a port of the focaltech ft5302 touchscreen controller driver, it's working on two tablets already and I hope to get it integrated into Linux soon-ish.
Kernel Driver Programming Course, The Hague. The date for the first day of the Kernel Driver Programming Course has been finalized, and is Sunday July 26th, from 12am - 6pm (end time is aprox.). As stated before the plan is to get together from then on every 2 weeks, so the next course day will ...
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Bertrik Sikken

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My attempt at making a mini word clock, in Dutch. The simple scribbled on symbols will be replaced by properly laser-printed white-on-black letters.
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+Frank Gevaerts How about I print them with Comic Sans?
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Bertrik Sikken

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Some insights gained while working on my https://revspace.nl/EspWifiTracker tonight:
* to get long battery life in a battery powered IOT-like application with an ESP8266, it is essential that the device can sleep efficiently
* the DS3231 is a nice 3.3V compatible real-time-clock chip but you cannot directly use its alarm output to trigger ESP8266 wakeup because it has a level-like output. If you tie it directly to the ESP8266 reset pin, it will keep the ESP in reset, so the ESP is unable to clear the DS3231 alarm (a dead-lock / chicken-and-egg problem).
* however, if you put a 1 uF capacitor in series to the ESP reset input, the DS3231 low-level alarm output is converted into a low-going pulse, which asserts the ESP reset only momentarily. This is a bit like how the classic arduinos receive a short reset pulse when the DTR signal goes low.

This should allow arbitrary long sleep times, with wakeup exactly on the time programmed into the DS3231 RTC.
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Another chip to consider, the PIC 12F1840 (soic-8) ... it draws even less power than the dallas clock chip (300nA with an external 32khz crystal). i2c interface to talk to the ESP (or plain uart). Configure it to emit a brief wake-up pulse to reset the ESP.
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Bertrik Sikken

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Aanstaande dinsdag bij de Haagse Makers: bouw je eigen LoRa gateway uit onderdelen:
http://www.haagsemakers.nl/forums/topic/project-diy-lora-gateway/#post-7673

LoRa is een radiotechniek die wordt gebruikt in o.a. "The-Things-Network", een gratis datanetwerk waarmee bijvoorbeeld allerlei low-power sensoren hun gegevens naar het internet kunnen sturen.
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Hoe maakt u het?
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Bertrik Sikken

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I just got online on The-Things-Network in Utrecht with an RFM95 module, an arduino nano pro mini 8 MHz/3.3V and the LMIC software.

Used this software:
https://github.com/Lora-net/LoRaMac-node
(modified the device id to my birthdate, changed all occurances of arduino.h to Arduino.h)

Data sent and received by TTN: http://thethingsnetwork.org/api/v0/nodes/19740823/?format=api
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I wish you had a gateway in Gouda  #thethingsnetwork  
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Bertrik Sikken

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Warning, Windows Update deletes GRUB!

After a windows update for Win10 on my dual-boot notebook, Linux no longer boots. It seems the grub bootloader got deleted. Instead of booting grub, Windows now shows me a flashing screen "All your files are exactly where you left them". Well, thank you very much ...
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Boris Gjenero's profile photoPeter D'Hoye (petur)'s profile photoMarten Lootsma's profile photo
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I had the same... https://help.ubuntu.com/community/Boot-Repair solved my problem
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Bertrik Sikken

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git pull --rebase
git checkout .
git clean
git clean -f
git checkout master
git reset --hard HEAD
cd ..
rm -rf XXX
git clone XXX
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Folkert van Heusden's profile photo
 
zo herkenbaar
git zou mergen simpeler moeten maken. nou mooi niet. argumenten zijn er ja.
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