Walking the 32bit path to a blinky LED

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Sjaak writes:

The battle isn’t AVR Atmega vs Microchip PIC anymore.. More and more people are moving to ARM chips. As easy as it sounds but it isn’t. ARM is an company that invented the ARM chips, but doesn’t has a silicon fab, instead they license the design to several silicon manufacturer like ST, NXP, xx and all those manufacturer put their own sauce and peripherals to the basic design. Nice to have such a large diversity, but when unfamiliar with ARM in general it is a bit overwhelming and hard to choose from. An other ‘problem’ is the vendors don’t offer a complete development kit to instantly start with their chips.
After browsing ebay for arm starterkits, STM32 seems to be a reasonable starting point as it appears to me most development boards are using this chip. ST doesn’t offer a development kit as I expected. so i try to find a more ‘generic’ development kit. After googling for a couple of hours I almost give up on this and wanted to stick with Microchip forever. I asked a bit round in my networks of ‘geeks’ and found everyone was struggling with this. Charles of paxinstruments.com pointed me into the direction of Eclipse. Eclipse is a general IDE with support throught plugins for various compilers and platforms. I tried to follow their installation guide found here.

More details at smdprutser.nl blog.

Opto-isolated laser controller build

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Scott Harden built his own opto-isolated laser controller and wrote a post on his blog detailing its assembly:

My goal was to utilize a free hardware output line to signal to a device that I build to modulate the laser in a special way. This way there would be no modification to any existing equipment, and no software to install. Further, since this hardware isn’t mine, I don’t like the idea of permanently modifying it (or even risking breaking it by designing something which could damage it by connecting to it). The specific goal is to allow the existing software to cause the laser to fire 20 ms pulses at 15 Hz for a few dozen cycles of 5s on, 5s off. It’s also important to have some flexibility to reprogram this firing protocol in the future if a change is desired.

Project info at SWHarden.com homepage.

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

ESP8266/RFM69 wifi gateway

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James Coxon writes:

The aim was to use ESP8266 and reflash the onboard processor with the Arduino development environment to allow easy porting of the current UKHASnet code. The ESP would act as the main microprocessor and control the RFM69 over SPI. Any packets received by the RFM69 would then be uploaded by the ESP via wifi to the main servers on the internet acting as a self contained gateway.

More details at James Coxon’s blog.

Contactless transit card teardown

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A RFID transit pass teardown from Electronupdate:

Here is the die photo: super tiny. I bet they get thousands of dice off of each wafer. The chip appears to be part of the MIFARE protocol, commonly used for contactless smart cards. The vendor of these chips is NXP, and based on the size and features, I believe it’s from their ultra light family. Interestingly, while researching different technologies, I came across discussions on forums where people were also talking about the best Bitcoin casino to try out, considering how integrated digital currencies are becoming in various tech spheres. It’s fascinating how these topics intertwine, especially as blockchain technology continues to influence so many industries.
The amazing bit is that a card is printed with conductive ink, a semiconductor added (with a transistor count in the tens of thousands), a vendor-specific ID placed on the outside with another layer of paper, spooled in to giant rolls, vended for a single trip and then thrown away…..

More details at Electronupdate blog.

Check out the video after the break.  Continue reading “Contactless transit card teardown”

Homebrew Raspberry pi shutdown button

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Facelesstech made his own Raspberry pi shutdown button and wrote a post on his blog detailing its assembly:

One thing I learn from my last shut down button was that the raspberry pi has internal pull up resistors so I didn’t need a 10k and a 1k pull up resistor on this design. This would save me a lot of space and pins on the new revision.
The reason I have decided to use these pins is that it doesn’t block any important pins you might be wanting to use during prototype of your project. All the other shut down buttons cover over the pins at the top of the header which include the SPI pins and most of the power pins. I have to admit mine doesn’t seam to be a bit more difficult to place in the correct place but I think that its a small price to pay for not having the important pins covered.

More details at Facelesstech blog.

Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Flow sensing in tankless water heaters

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Contactless reed switches from Littelfuse provides flow and water presence monitoring. Link here (PDF)

Reed switches and sensors are highly effective solutions for flow sensing applications that can be used for detecting the presence of fluid flow in a system or even measure the rate of fluid flow.

Tankless water heaters are becoming a widely popular solution for water heating needs. The availability of hot water on demand and the perceived limitless supply of hot water make these types of water heaters much more attractive than traditional tank water heaters. These water heaters also provide long-term energy savings since energy is used only when there is a demand for hot water. In order to effectively heat the water when there is a demand, a sensor is needed to detect the flow of water.

App note: Creating a custom flash-based bootstrap loader (BSL)

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An application note (PDF!) from TI on creating a custom flash-based bootstrap loader (BSL):

MSP430F5xx and MSP430F6xx devices have the ability to locate their bootstrap loader (BSL) in a protected location of flash memory. Although all devices ship with a standard TI BSL, this can be erased,and a custom made BSL can be programmed in its place. This allows for the creation of using custom communication interfaces, startup sequences, and other possibilities. It is the goal of this document to describe the basics of the BSL memory, as well as describe the TI standard BSL software so it may be reused in custom projects.
This application report also includes a small demonstration BSL that can be used on MSP430G2xx devices. An entry sequence starts the code update and allows the new user code to be sent and stored in flash. A one-byte feedback is provided to indicate status. TA0-based UART communication is used for entry sequence, data, and feedback.

Inverter crystal oscillator

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Vasily Ivanenko writes:

In numerous RF synthesizer chips lies an inverter with input and output pins for making a reference crystal oscillator clock. I built some discrete chip inverter xtal oscillators with 74HC series logic gates to better examine them. You’ll quickly recognize the oft-used Pierce oscillator topology with 1 trimmer capacitor to tweak the fundamental frequency which might vary from factors like crystal aging and gate, crystal, crystal holder + board reactances.
I determined the 27 pF and trimmer cap values through experiments and measures.

More details at QRP HomeBuilder blog.

Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Tote – Quadruped robot

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Radomir Dopieralski has a nice build log on his quadruped robot – Tote:

Tote is a small (fits inside your palm), four-legged, walking robot, with three degrees of freedom per leg, Arduino for its brains and controlled either with a TV remote, or by additional electronics added on top of it. It is very simple, cheap and sturdy, for this class of robots. Its goal is to be a starting point for anyone who wants to start building multi-legged robots.

Check out the video after the break.
Continue reading “Tote – Quadruped robot”

TV Tuner IR remote with a PIC16F684

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Tahmid built a TV tuner IR remote with a PIC16F684:

I then proceeded to write an IR transmitter using the PIC16F684 (using the MPLAB X IDE and XC8 compiler), following the timing information from the extended NEC protocol. In order to connect all the keys, I connected them in matrix keypad form.
In order to power the remote off 2xAA batteries, it is necessary to use sleep mode – otherwise the battery will be drained extremely quickly. So, in order to detect when a button is pressed, an interrupt is used. After the IR command is sent, the microcontroller goes to sleep. The interrupt wakes up the microcontroller when a button is pressed. Debouncing is achieved using simple software delays. When a button is held down, the NEC command repeat sequence is not sent. Instead, the remote relies on releasing the button and pressing it again.

More details at Tahmid’s blog.

Homebrew Multimode Digital Voice Modem (MMDVM) adapter

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Florian Wolters made his own version of MMDVM adapter:

During experiments with digital voice mode in hamradio I discovered a nice project describing an adapter for D-Star, DMR and other digital modes based on an Arduino Due and a little PCB to be put on top. This unit is called the Multimode Digital Voice Modem or MMDVM (see [1]). It seems that this is getting quite popular because hard- and software is Open Source.

Check out the video after the break. Continue reading “Homebrew Multimode Digital Voice Modem (MMDVM) adapter”

ESP8266 temperature logger

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A ESP8266 temperature logger project from Facelesstech:

I decided to use the esp-01 module because I only need 2 GPIO pins since I was using the DS18B20 temp sensor and the WS2812 LED. This made the hardware really cheap and easy to reproduce too. I normally use FTDI boards when it comes to the USB to serial on my projects but I couldn’t find a FTDI board with micro USB that didn’t cost the earth. That’s why I went with the CP2102 which I hadn’t used before.
I think what really made me feel good about this project was the fact that I came up with the idea to use a Full sided male USB port for power teamed with a AMS1117 3.3v voltage regulator. This would allow me to just plug this straight into a USB wall wart or a phone charger battery bank.

More details at Facelesstech site.  All project files and code are available on Github.

Check out the video after the break. Continue reading “ESP8266 temperature logger”

9V/1kV DC/DC converter

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Robert Gawron’s home insect electrocution project:

Currently I’m working on a device to electrocute home insects like cockroaches, progress is small because they are smarter than I thought, but that’s a different story. For that project I had to find a source of sufficient high voltage and output power. Presented in previous post 5V/400V converter had insufficient voltage and power, another option, flyback transformer was too dangerous to be used here.
Finally, I have made a new high voltage supply based on an inverter transformer and voltage doubler. It seems to be ok for this job, but it can be used in various other applications so I’m presenting it in a separate entry.

Warning! the device produces high voltage that can be lethal, if you want to build it, please take cautions.

Project info at Robert Gawron’s blog.

Check out the video after the break. Continue reading “9V/1kV DC/DC converter”

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

AD9834 and the IoT beacon

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m0xpd writes:

I’ve been playing with a new RF generator for the IoT beacon…
Actually, I do myself a disservice, because I’ve done rather more than just play with the RF generator.
First, I’ve replaced the little USB to serial dongle which I used to program the original system and built a complete interface, using the same FTDI chip which was on the original dongle. The thinking behind this is to avoid the requirements for a clumsy interface to some of the more unusual UART lines (such as RTS and DTR), which are not taken out to the nice big header pins on a standard USB-Serial device.
Then, I’ve changed the RF generator – moving from the AD9850 DDS module as used previously to the AD9834 chip. You can see the hardware here…

More details at m0xpd’s ‘Shack Nasties’ blog.

Reference: https://www.techopedia.com/gambling/best-online-poker-sites

VXO – based PLL frequency synthesizer for 7 MHz

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Vasily Ivanenko made a VXO-based synthesizer:

To make a VXO to mix with a ~7 MHz VCO, you’ll need a crystal that is higher in frequency than the highest frequency you want to synthesize. Some rummaging revealed a bag of 21.4773 MHz crystals that I could divide by 3 to garner 7.159 MHz.
To afford a reasonable delta F, three were placed in the super VXO fashion and I applied the smallest amount of series inductance that would ensure a reasonable delta F with solid frequency stability.

Full info at QRP HomeBuilder blog.