Actvities at the lab

Temperature, Light, Pressure, Humidity

posted Jan 11, 2017, 2:24 PM by JERRY DUNMIRE   [ updated Jan 11, 2017, 2:26 PM ]

Work on a new ESP-8266 based sensor node to measure temperature, light, pressure and humidity is already on to version 2. Details can be found at the Sensornode Site.

Sensor Nodes

posted Jan 1, 2016, 8:32 AM by JERRY DUNMIRE   [ updated Jan 1, 2016, 8:33 AM ]

Information on my IoT sensor node for temperature and light is finally available. The project is bigger than the typical exercise/experiment published here, so I setup a separate website.

Both the software and the hardware are open for this battery operated, network connected sensor.

Please follow along at

OLED/i2c library for ESP8266

posted Apr 12, 2015, 10:25 AM by JERRY DUNMIRE

My take on code for a 128x64 bit OLED display driven by an ESP8266 is now available on BitBucket.

The code includes a compile time option to rotate the display 180 degrees and a test program that demonstrates all of the OLED functions.

A Python script is included to generate bitmap arrays from .ppm files.

This will be used in an upcoming ESP8266 based MQTT display.

SSL/TLS Client Certs to Secure MQTT

posted Feb 13, 2015, 7:53 PM by JERRY DUNMIRE   [ updated Feb 13, 2015, 7:55 PM ]

The exercise is a step-by-step procedure to generate client certificates for use with MQTT. The mosquitto broker and command line clients are used to demonstrate certificate use.

OpenVPN Community Edition on an AWS EC2 instance

posted Feb 8, 2015, 7:58 AM by JERRY DUNMIRE   [ updated Feb 8, 2015, 8:06 AM ]

While travelling last summer I wanted a way to secure my network access while using open WiFi access points. After a bit of research I decided to run OpenVPN on a free AWS EC2 instance.

Full details for this exercise, including several scripts and sample configuration files are available from

HC-05 Recovery

posted Jan 29, 2015, 7:14 PM by JERRY DUNMIRE

The HC05Recovery exercise explains how you can restore communications between an Arduino UNO and an HC-05 with incompatible serial port settings.

Privacy Policy

posted Jan 1, 2015, 2:11 PM by JERRY DUNMIRE

I have been wondering how much this site is used by others and decided to experiment with Google Analytics to find out. Since Google Analytics collects data visits to this site, the service requires me to tell you about what data is collected and how I use the data. I.e., a Privacy Policy.

In addition to the link in this post, you will always be able to find a link to the policy in the Navigation bar to the right.

Working with a cluttered desktop

posted Oct 26, 2014, 11:39 AM by JERRY DUNMIRE

Using a mouse button to activate the Unity Spread function is an easy way to find the window you want when it is buried deep on your cluttered desktop. But, finding the controls to bind Unity Spread to a mouse button is difficult due to inconsistent terminology.

The Ubuntu and Logitech M705 buttons exercise is a step-by-step procedure for setting up the mouse button binds for a Logitech M704 mouse.

First 24hrs with Raspberry Pi and WSPR

posted Aug 25, 2013, 10:12 AM by JERRY DUNMIRE   [ updated Aug 25, 2013, 10:29 AM ]

It works! I have a Raspberry Pi transmitting WSPR and it has been heard.

Map from WPSRnet

Using WsprrPi is easy- to transmit on three different bands in rotation with frequency calibration using NTP  the command line I used is:

$sudo ./wspr -r -s KA6HLD CM97ai 10 20m 30m 40m

The set up is cobbled together and strung out over most of my shack. I used the JamesP6000 version of the WsprryPi program, a low pass filter from Kits and Parts dot Com that I analyzed in the  RF Filter for a Raspberry Pi Transmitter exercise, and my MFJ Multi-band vertical.

The vertical is not in good shape (broken counter poise wires and other problems) and I didn't check the SWR. Still, the 10mW signal from the Raspberry Pi was heard on 2 bands by 4 different stations. W0AY, on 30m in Montana, recorded the most reports (63) over the first 24 hours. Reports on 20m were from N0HAV, K0SQL53, and  the distance winner (2041 km) VE6PDQ.

This has been great fun and I recommend that anyone with a Raspberry Pi and an Amateur Radio license give it a try.

Next I need to look into WSPR reception...

RF Filter for a Raspberry Pi Transmitter

posted Aug 20, 2013, 9:18 PM by JERRY DUNMIRE

The RF Filter for a Raspberry Pi Transmitter exercise analyzes two filters in order to choose a filter for use when transmitting a WSPR signal using the Raspberry Pi.

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