Arduino not visible on COM port. Cannot upload a sketch even if you have flashed a fresh booloader. Solution.

If your Arduino does not show up on any USB COM ports even if you flashed a fresh bootloader, it may be because the sketch you flashed has messed up your USB serial settings on the Arduino. This sketch will prevent the Arduino showing up as a com port in Windows because the flashed sketch starts immediately upon reset and “blocks” the normal USB COM operation.

Solution:
1) re flash the bootloader with an ISP connected to the 6 pin header. I use a USBasp (cheap ISP clone).

2) Just so you KNOW the bootloader is installed. You can check that the bootloader is operational by plugging in the board thru the USB COM port (when you already have an open hardware manager windows in Windows).
You should see briefly a new COM device named “Arduino [name of board] bootloader”. This  COM device will quickly disappear again if you have a sketch messing up the serial settings.At least you know the bootloader should be OK.
3) Upload a completely empty sketch WITH THE ISP device. Important!:Do that upload with the ISP and NOT via the USB serial cable.

This is a completely empty sketch you can use:

void setup() {}
void loop() {}

I have fixed several dead Arduino boards that I suspected had hw problems this way. In fact the boards were OK. The problem was that a sketch already installed messed up the serial settings. The bootloader and hw was completely ok.

RTOS on Arduino

FreeRTOS Task for Blink LED in Arduino UNOProfessional software developers of time critical code often use a real time operating system (RTOS) in their work. The reason is that the OS is taking care of timing and scheduling tasks with higher priority. Now you can easily use an RTOS on your Arduino as well! Read Jain Risbah’s article over at circuitdigest: https://circuitdigest.com/microcontroller-projects/arduino-freertos-tutorial1-creating-freertos-task-to-blink-led-in-arduino-uno

IRIDIUM SATCOM enabling your next IoT / Arduino / microcontroller project

Rock Seven has launched a board that takes care of the PSU and antenna requirements to support the Iridium 96090 module https://www.iridium.com/products/iridium-9602/

http://www.rock7mobile.com/products-rockblock.php?gclid=EAIaIQobChMI1ZWSqv2C3gIVRawYCh2DBQ7eEAAYASAAEgI3vfD_BwE

This enables fast time to market and coverage in remote areas on customers IoT devices.

How to develop and debug C++ code for Arduino in Visual Studio if you are tired of the Arduino IDE

The Arduino platform has gained a fantastic popularity over the past ten years. For small quick and dirty projects, the .ino files and the standard IDE is OK. However, for professional development projects and for developers that want control over the .hpp and .cpp files the standard Arduino IDE is somewhat regarded like a toy. Furthermore there is no proper debugger in the Arduino IDE  (whaaat?, you gotta be kidding?)

Well, this has changed as Visual Micro has developed a plugin to Microsoft Visual Studio. You can write code the normal way you do it with .cpp and .hpp files. You can also run the GDB debugger. The IDE has support for the regular .INO files and Arduino libraries. Here is how both .cpp and .ino files are handled: http://www.visualmicro.com/page/User-Guide.aspx?doc=INOs-and-CPPs.html

There is a free version of Visual Micro and it works against the free versions of Microsoft Visual Studio 2017 Community Edition. All you need is a Microsoft account to be able to download and install Visual Studio 2017 Community edition. Then in MSVC 2017, go to tools, Extensions and Updates and enter a search for Arduino in the search bar. It will will offer to automatically install the Arduino tools and the GDB debugger. Click install and you are on the right path.

Links:
http://www.visualmicro.com/
https://marketplace.visualstudio.com/items?itemName=VisualMicro.ArduinoIDEforVisualStudio

If you find this tip useful, please share on facebook and share the link. Also, feel free to report your experiences in the comment field.

HDSDR trackerball VFO project

I have been working on a trackball based controller for my HDSDR SDR project lately. This is a small R&D project that is run on my spare time where the goal is to determine if it is possible to use a trackball as a VFO for software defined radio (SDR) in contests. The project started out based on a demand for a more ergonomic way to operate a mult receiver in a contest environment that is less fatiguing during 48hours duration of a major contest like CQWW or CQWPX. The goal is that it should be possible to operate all radio functions you need from one hand only: VFO, speed of vfo, band, mode, filter width, volume, gain. I have modified a Marconi trackball and the controller is a Trinket Pro controller (Arduino)

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RF current amperemeter with log detector

I have long had the need to measure antenna current. This can be done by a rf-current transformer and a rectifier made by a shottky diode or fast silicon diode and an integrator driving a mechanical instrument. However the dynamic range is very limited with such a setup.

Therefore I made a new rf-amperemeter design with a log detector chip from Analog Devices driven from a current transformer made out of a split core ferrite material that has response in the HF and lower VHF frequency range.The current trafo is terminated in a few ohms and the RF current conductor (actually the primary) sees only a fraction of an ohm so very little influence is done on the circuit you are measuring. (Apart from capacitive coupling and a slight leakage inductance from the current transformer windings/ferrite combination). The ferrite core is a split type and is epoxied to a clip.

I calibrated the instrument by terminating the generator in a fancooled 100W dummy load and measured the voltage over the load by an oscilloscope. Since it has a log output the dynamic range from milliamp range up to 1,4A RF current. That would peg a mechanical instrument if you would at the same time want to be able to detect a significantly lower RF-current without having to change scales with switches / pot meters etc.

Next I plan on making a OLED display on this design with an arduino controller. Its a sparetime project so lets see how long tiem it takes before I implement that.

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Arduino Based CW keyer / FTDI based CAT interface

I recently needed a new CW keyer with Winkey compatibility for use with my N1MM logging setup. K3NG has written some nice keyer code that I compiled and uploaded to one of my Arduino UNO boards that I had laying in the shack (if you want to try it, you need the latest  – above 1 – version of the Arduino “IDE”). Below you can see some pictures from making the prototype thru to ready made keyer with USB interface and adjustable speed button. I did not install the memory buttons, as I control the CW keyer via USB from N1MM or Hamradio Deluxe. It works very well with my Yaesu FT-450D but instead of the UNO I will eventually use a Mini Pro board with the Atmel Atmega 328. You can see more info on K3NGs site http://radioartisan.wordpress.com/arduino-cw-keyer/#comment-3255

Below is the schematic (remark: full credit is given to to K3NG!). I have modded the design for my own needs. Instead of the 2N2222 I use a TTL tolerant FET of type IRLIZ44N to drive the keyer output. Then I don’t need the 100 ohm resistors in series. I also did connect a piezo tweeter directly to the CPU  without using the 2N222 transistor. It works OK. However, the sound of the piezo tweeter is not the best in the world. Finally, as mentioned above, I did not install all the buttons. I installed only the command button to save space.  There is a need to do a small mod on the UNO hardware due to some reset issues. For that I will have to add another button that needs to be pressed when I want to upload code.

http://radioartisan.files.wordpress.com/2011/03/k3ng-keyer-schematic-2012052101.png

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I also needed a CAT interface. It is possible to use a FTDI chip for this task, however the signal levels need to be transformed to +/- 12V. This I solved with a MAX232 board that I had laying around in the shack. So now I have a CAT interface that is compatible with Win XP, NT, 2000, 98, Windows 7, Windows 8 etc since the FTDI chips are widely supported. It looks like … but works like …

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