Wifi techniques explained

MIMO and MIMO at stanford.edu

Channel bonding

Spatial Multiplexing

Also have a look here on why an Ipad Air performs better then an Iphone 6


How to monitor a tcp or udp port on OSX

Two ways…

Let’s say you want to monitor udp port 55057.

nc -u -l 55057


tcpdump -i en0 -X -v ‘udp port 55057’

More info on nc

Arduino experiments with a led strip

Underneath code activates a led strip based on the state of a light sensor :

int ledPin = 13; // LED connected to digital pin 13
int inPin = 7; // light sensor connected to digital pin 7
int val = 0; // variable to store the read value
int ledstrip = 9; // ledstrip connected to ping 9

void setup()
pinMode(ledPin, OUTPUT); // sets the digital pin 13 as output
pinMode(inPin, INPUT); // sets the digital pin 7 as input
pinMode(ledstrip, OUTPUT); // sets the pin used for the ledstrip as output

void loop()
val = digitalRead(inPin); // read the input pin

if (val) {

digitalWrite(ledPin, val);
Serial.println(“Too dark… Activate lightning…”);

for (int brightness=0;brightness<256;brightness++) { analogWrite(ledstrip,brightness); delay(10); } // stay on for 5 sec delay(5000); // now dim back to off, but slower for (int brightness=255;brightness>0;brightness–) {


else {

digitalWrite(ledPin, val);

Background info : http://www.jerome-bernard.com/blog/2013/01/12/rgb-led-strip-controlled-by-an-arduino/

Arduino and NRF24L01

Just ran some quick test with two NRF24L01 modules…

Conclusion :

Distance between two modules is in my case not very large.  Probably due to walls in appartment, interference from other equipment etc…  External antenna’s would be a solution, but then this would mean more power.  Then need to verify if an Arduino Uno can take this amount of power…

Documentation used :




Testing a digital input signal

Created a quick Arduino setup where an attached pir sensor provided a trigger on pin 13 of the Arduino.  This pin was connected to IO1 of the unipi.  The unipi uses the gnd coming from the Arduino (so the jumpers on the unipi are set to the side of the label).

Code :

import RPi.GPIO as GPIO

import time



GPIO.setup(4, GPIO.IN, pull_up_down = GPIO.PUD_UP)

while True:

if(GPIO.input(4) == 1):

print(“No Input signal detected”)



print(“Input signal detected”)


Two conclusions.  First a signal is detected on a low on the port.  Secondly, even 4,88 Volts trigger an event (maybe even lower, can’t test right now).

Dynamic dns and Cloudfare

Ever since dyndns stopped their free service, my dynamic dns at home stopped working also.

Since i have some upcoming projects with home domotica, i was in desperate need of a fix.  Cloudfare to the rescue.

Only thing i needed to do is run through a wizard at Cloudfare, which would investigate my current domainname.  At the end of the wizard, it proposes to have my current registrar change the domain so two authorative dns entries are added.  After that we can play with all regular dns settings (A, CNAME records,…).  Bonus, Cloudfare allows url forwarding.  So i could link this blog in WordPress again to my domainname.  Great!  And all for free.

O yes.  I have a Freenas running 24×7.  I uploaded a script there to update my (dynamic) ip to Cloudfare.  Did not have to invent anything.  Howto is found here.

Starting blogging again

Okay, it has been a while.  Haven’t had time to write all my stuff down.  And honestly, did not have the pleasure in doing so.  But lately i’m having so many projects going on… that i have to write something.  So watch out…  Lot’s of articles coming dealing with raspberry pi.

Installing a Zumo 660 on a Burgman 650

We will be connecting the wires to the 12V socket.  The mounting will happen on a ram mount plate assembled on the left brake oil reservoir.  I won’t go into much detail how to remove the tupperware.  Check out the instructions of ledude.

Remember to remove the scrivets :



With those two panels removed, you can remove the front panel.


Once the panel removed, you can see the wiring of the 12V connector.  You can simply remove the sockets, insert the cabling of the Zumo, and insert the sockets again.  The connections seem solid enough.  Tie the exces cabling to the framework.


Here’s a closeup of the sockets :


Test before you install all the tupperware again in reverse order.  Also check you have enough slack in the cabling when you turn the steering.

How does it look in the end?


Sideview :


With Zumo gps mounted :


Zonnepanelen en verbruik

Stilaan zijn zonnepanelen toch wel interessant. Maar wij wonen in een appartement. En er mogen/kunnen geen zonnepanelen op het dak. Of aan de balkon. Dan maar niet? Of toch wel? Want tegenwoordig bestaan ook vouwbare zonnepanelen. Deze zijn vooral bedoeld voor caravans en campers. Reden genoeg om wat te grasduinen…

Uit bmsat.nl

Stel een verbruik van :

Apparaat                    Vermogen    Uren aan   Verbruik
2 lampen 15 Watt      30 Watt         3                  90 Wh
Waterpomp                60 Watt         0,5               30 Wh
Televisie                    50 Watt         2                  100 Wh
Radio                         10 Watt         5                  50 Wh
Gem. Dag. Verbr.                                                270 Wh

Onderstaande panelen geven een indicatie wat we in NL/België kunnen verwachten als opbrengst…

Type paneel Watt-uur/dag
75                    300
85                    340
100                  400
110                  440

Een 75W paneel zou dus voldoende zijn voor bovenstaande…? Door de ongunstige plaatsing op het terras in een appartement zal de opbrengst nog wel wat minder zijn… Maar hoeveel? En wekken we genoeg energie op om bijvoorbeeld al onze mobiele apparaten te laden. Voer voor verder onderzoek…

Een zeer interessant artikel is van Guido Clinckemaillie.

Starting with Raspberry Pi

Finally started playing with a Raspberry Pi.  This little box is a neat way to join my electronics education background and real life linux experience.  It installs like a breeze.  And all the stuff you need to get started is on there already.  The little box seems to only consume 4 Watts.  Which is terrific.  And opens a whole new world of possibilities.  I already ordered some extras on ebay to start playing…  Piezo buzzers, reed magnetic switches, a kit including a bunch of jumper wires, breadboard, T-cobbler, lcd, PIR sensors, etc…  This should keep me busy for a while…  One of the main uses would be home security.  Secondly i would like to investigate home automation.  This looks a bit more difficult as it needs interfacing with for example garage door openers.  And i don’t think vendors will be too keen on providing info on which pins on their hardware we need to connect…  We’ll see… Awaiting hardware to play with…

Oh yeah, this eoo shop seems to sell nice electronics for interesting prices…