Uploading code wirelessly to Arduino Mega

Given the same thing worked ok using an Arduino UNO form-factor board with both an AVR 328p and an ESP8266, I was expecting not much trouble getting the same thing to work for a similar board in the Arduino Mega format.

Oh boy, I was wrong!

The hardware modification part was easy: Find the diode whose cathode is connected to the RESET pin and remove it from the board. (Board schematic)

I used GPIO12 as the ESP8266 pin to be used to reset the AVR processor (key for a remote upload).

But once the hardware was working, it became obvious the software side of things was just not working. I could see no communication was ever successful between the ATMega2560 and avrdude program.

Reset generation was not a problem as it was clear remote reset was working ok. Perhaps timing? Let us read about possible issues on github. It turns out this is old news, as ESP-Link is playing a trick to detect the attempt of a firmware upload so it can reset the AVR chip then. That detection was limited to the m…

Uploading code to your Arduino board remotely

A while ago I bought some Arduino UNO and Mega cards that featured, besides the usual processor, an on-board ESP8266 processor to bring Wi-Fi connectivity to them. Theseboards, have DIP switches to be able to program either the AVR (Arduino) processor or the ESP8266 using the USB port (think of them as a sort of serial port multiplexer).

The main use for me was to be able to use them for different applications without using a USB cable. A [Wi-Fi]  TCP connection to port 23 would be used instead. As I am using ESP-Link firmware for the ESP8266.

Do you want to print wirelessly on your 3D printer? You can do that with one of these Arduino Mega boards that can use Marlin. Using Pronterface software you can print to a TCP socket the same as if you print to a serial port.

However, what intrigued me is that no mention was made in the boards I use about using the ESP8266 to upload new programs to the Arduino processor. And that was odd as ESP-Link software allows you to do that. However, in o…

Plot real-time data with Python

I am involved in a project to create a tensile tester for a friend. I have never used a tensile tester myself so I have to play by ear here. But it occurred to me that not much more than a strong 1-dimensional axis would be needed. So we built a mock-up using a stepper motor, some old guides from a sliding door and threaded rod connected to both the motor shaft and a nut that was soldered to the moving carriage.

The second part of the contraption was to set a load cell on one end so a test piece could be fixed between the load cell and the moving carriage. As the carriage pulls away from the load cell, the specimen response could be measured and graphed.

Using an Arduino was the obvious choice this time, as it was, in fact, the only choice, given my friend is building this thing at home, three thousand miles away from me and we all are under covid19 lockdown. He only had one Arduino Mega at home, so that is what we will use.

I thought that specimen test data could just be sent to a PC…

First impressions on Prusa MINI

Although I bought the unit back in October 2019, it seems I was not the only one, so it has been a while until I have received my unit, but just last week, during the lockdown, I was pleased my new printer arrived.

The main goal was for this printer to be a tiny 3D printer to have on my desk at home. I have been very pleased with Prusa's MK3 printer that provided me with reliable prints every time I need it. I just thought a smaller printer would be ok at home, as most of the time I do not need the extra volume the MK3 can do.

Building the Prusa MINI was quite straightforward and it took me less than one hour. I guess it can be done much faster once you are familiar with the model.

The new LCD graphic color display is one step forward from the older LCD used in the MK3. It is kind of small so I did not miss it was not touch-sensitive.

Once it was built and working, I checked the firmware version and it was, indeed, running the latest version.  So the next step was to print someth…

Improving your streaming game

After my first on-line lecture I have got some interesting feedback from my students and from my own experience too. While it felt odd during the first few minutes, the fact I saw many of my students were there and that setup mostly worked made me relax a bit more during the second half of the class.

But, first of all, let me tell you what worked well and what did not:

Asking the students to post a comment for attendance record worked extremely well in my opinion. As it allowed me to put faces to the online viewers counter, while it also reassured me my students were ready, which also relaxed me as I was worried they might not show up.Comments allowed students to report audio trouble when it happened and me fixing it quickly. Of course, comments also allowed students to raise questions about the topics I was talking about, which make the lecture a bit more interactive and, hopefully, useful and entertaining.I found myself at times uneasy as I have not a pointer to signal on the slides …

Youtube streaming for dummies (and for me too)

The coronavirus crisis forced us all to stay home. Those of us in the education business are instructed to keep going using online resources. But given the current state of laws, I am reluctant to distribute any personal information (and that includes emails) to any available webinar platform. Several of them have been suggested like GoToMeeting or Zoom by my friends. We have Microsoft's Teams on-campus package but, for some reason not all my students are on the platform.

So it appears the simplest thing to do is to just use youtube streaming service, that allows hidden videos/streams, only accessible to those who know the URL. And I could email the stream info to my students by email without revealing their email information to anyone. So that sounds like a plan but ... there are a few caveats:

While I do know how to stream a video out of a webcam (as simple as pressing the upload button and choosing "Go live"), just the idea of a talking head does not seem very appealing…

The interesting world of VAWTs

I was curious about the type of wind turbines that do not need to face into the wind. So I googled
around to learn they are called Vertical Axis Wind Turbines (or VAWTs). But that is not all there is to it. There are a handful of different designs built around two basic concepts: drag and lift. And as you can guess, these are not as efficient as the more popular Horizontal Axis Wind Turbines (HAWTs) found on most wind farms.

The beauty of the VAWT is their simplicity: Just a special shape the wind will rotate and, if connected to a generator, it could be used to produce energy too. But its power-generation capability is somehow smaller (if you consider the frontal area it presents to the wind) than the propeller rotors of the HAWTs.

On the other hand, some of the designs, have been created quite simple so they can be built repurposing other objects. For example, the basic Savonius rotor can be built by joining two halves of an oil barrel in an S-shape configuration. Any other cylindr…