Edge-lit seven segment display

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Debra over at Geek Mom Projects posted detailed instructions of how to build this edge-lit seven segment clocks:

This build combines small dozens of small laser-cut acrylic pieces which fit together with very tight tolerances. It uses skinny (4mm wide) LED strips which must be soldered, bent, and then slotted in between those acrylic pieces. When assembling the parts you must be willing to force pieces into place, even though it feels like you are stressing the brittle acrylic. You must also be willing to remove and re-seat said pieces and LED strips when it turns out they *can’t* actually be forced into place. At some point during the assembly there is a strong likelihood that you will have to remove everything and re-solder your LED strip when you realize that forcing everything into place broke one of the wires away from your LED strip or created a short circuit.

See the full post on Geek Mom Projects blog.

Check out the video after the break.

Minimal ATSAMD21 computer

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Johnson Davies shared detailed instructions of how to build an ATSAMD21-based computer on a prototyping board using a 32-pin ATSAMD21E:

If you’re looking for something more powerful than the ATmega328 in the Arduino Uno a good choice is the ATSAMD21. This is an ARM Cortex M0+ processor with up to 256KB flash memory, 32KB RAM, and a 48MHz clock, so it’s substantially better equipped than the ATmega328. In addition it has a USB interface built in, so there’s no need for a separate chip to interface to the serial port.
Arduino have designed several excellent boards based on the ATSAMD21, such as the Arduino Zero or smaller-format MKRZERO. However, these boards are an expensive way to use an ATSAMD21 as the basis for your own project, and they probably include many features you don’t need.

More details on Technoblogy.

Wifi based DIY 5V switcher for led-lights

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Albert posted a detailed how-to on building DIY ESP-12F based USB-5V switcher:

5V powered 100LED circuit was consuming around ~1.8Watts(though 5.1Ohm series resistor was really hot) and the brightness of the LED’s were not bad, especially difference between first led and last led brightness didnt bother me it was hardly noticeable when seen from distance. So I decided to use them as a christmas decoration for my garden.
I wanted to use them with battery-bank as there was no power-outlet readily available(for the safety of my children, i would avoid any 230v circuit in my garden especially in wet weather). Also I wanted them to be switchable remotely to avoid going out in the freezing cold. Hence this is what i came up with.. an “ESP-12F based USB-5V switcher”

See the full post on his blog.

So how to do CW on a homebrew SSB rig?

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Pete Juliano, N6QW, has written an article on how to do CW on a homebrew SSB rig:

The Answer is Not a Flippant: Carefully!
Author’s note: A friend in VK4 land made an inquiry about CW operation. I find that 99.99% of my operating time is SSB. But others spend a greater time on the air using CW so why not share some info and data that I have stashed on my computer where a SSB rig can be made to work CW. This also open the possibility of filter switching for a more narrow pass band. With Arduino anything may be possible.

More details on Pete Juliano’s (N6QW) blog.

Remote debugging with USB based JTAG/SWD debug probes

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Erich Styger wrote an article on how to turn a USB debug probe into a IP-based debug solution:

For some projects it is not possible to have the device under debug available on my desk: the board might be in another room, on another site or in a place where physical access is not possible or even dangerous. In that case an IP-based debug probe (see Debugging ARM Cores with IP based Debug Probes and Eclipse) is very useful: as long as I can access its IP address, that works fine. It is an excellent solution even if the board is moving or rotating: hook it up to a WLAN access point and I still can use it as it would be on my desk.

More details on MCU on Eclipse homepage.

ATtiny13 – 8bit mono class D amplifier

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Łukasz Podkalicki shared a how-to on building a Class D amplifier on ATtiny13:

I always wonder whether it is possible to make an amplifier of class D on ATtiny13 or not. Some time ago I found George Gardner’s project based on ATtiny85 – TinyD. It was a sign to start challenging it with ATtiny13. It took me a few hours but finally I made it! The code is very short and useses a lot of hardware settings which has been explained line-by-line in the comments. The project runs on ATtiny13 with maximum internal clock source (9.6MHz). It gave me posibility to use maximum of hardware PWM frequency (Fast PWM mode).

See the full post on his blog.

Check out the video after the break.

Outdoor UV index sensor

Outdoor UV index sensor

A detailed instructions of how to build this outdoor UV index and ambient light sensor from Mare & Gal Electronics:

The VEML6075 senses UVA and UVB light and incorporates photodiode, amplifiers, and analog / digital circuits into a single chip using a CMOS process. When the UV sensor is applied, it is able to detect UVA and UVB intensity to provide a measure of the signal strength as well as allowing for UVI measurement.

Semiconductor radioactivity detector – part 2

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Robert Gawron has been working on a radioactivity detector, that is available on GitHub:

There are many ways to measure radioactivity level, semiconductor detectors sense interactions between ionizing radiation and p-n junction. Because in hobbyist area most popular are Geiger-Muller based detectors (in short: not a semiconductor but lamp based devices), I think it’s a cool idea to take a look at this approach.
In this post I will present such home-made sensor and a set of software to parse collected results.

See the full post on his blog. Be sure to see Part 1 here.

Tutorial: Booting the NXP i.MX RT from Micro SD card

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Erich Styger has written an article on how to boot the NXP i.MX RT from Micro SD card:

It is a common thing to boot a Linux system (see the Raspberry Pi) from a micro SD card. It is not that common for a microcontroller. The NXP i.MX RT ARM Cortex-M7 fills that gap between these two worlds. No surprise that it features a ROM bootloader which can boot from a micro SD card.
Booting from a SD card is kind of cool: load a new software to the card, insert it and boot from it. In some applications this can be very useful: in my configuration the processor starts the ROM bootloader, then loads the image from the SD card into RAM and then runs it. In that configuration no internal or external FLASH memory would be needed.

Via MCU on Eclipse.

Viewing ARM CPU activity in real time

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Jeremy Bentham writes:

In previous blog posts, I have described how an FTDI USB device can be programmed in Python to access the SWD bus of an ARM microprocessor. This allows the internals of the CPU to be accessed, without disrupting the currently running program.
In this blog I take the process one step further, and add a graphical front-end, that shows the CPU activity in real time

More details on Iosoft blog. Source files are available on GitHub.