Plan C: Make Better Now (Video): How 100,000 Volunteers Made Millions of PPE

If you want to get a sense of all the makers around the world producing PPE over the last several months, watch this video that captures the spirit and spread of these efforts.  How makers have collaborated on solutions and produced PPE in local communities is a big story, one […]

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Open Source Hardware Certifications For June 2020

The Open Source Hardware Association (OSHWA) runs a free program that allows creators to certify that their hardware complies with the community definition of open source hardware.  Whenever you see the certification logo, you know that the certified hardware meets this standard. The certification site includes a full list of […]

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The Solid State of Things

Hello everyone and welcome back! This week we have five new products to show off, and it all starts with the hefty new Qwiic Solid State Relay Kit. With this you will be able to control up to four 40A relays, so make sure you know how to handle large amounts of power!

Following that, by on popular demand, we have a new version of our Qwiic Button, now with a green LED rather than red. We also have a Raspberry Pi Compute Module, the MI:power board for your micro:bit, as well as a new 10W solar charger.

Summer activities canceled? Welcome to SparkFun Summer Camp! We’ve got your classic camp fun covered online – with an electronics twist. Check out our activity schedule, and let’s have some fun! This is our third week of sales, which means we are focusing on robotics (next week is machine learning!). Don't forget that you can get a free SparkFun Qwiic Pro Micro BoogieBoard with any purchase of $75 or over using promo code "BOOGIEBOARD20" (some restrictions apply).

Now onto our new products!

Huge power options, kinda small package!

SparkFun Qwiic Quad Solid State Relay Kit

added to your cart!

SparkFun Qwiic Quad Solid State Relay Kit

In stock KIT-16833

The SparkFun Qwiic Quad Solid State Relay Kit takes one of our favorite solid state relays and lets you place up to four of t…


The SparkFun Qwiic Quad Solid State Relay Kit takes one of our favorite solid state relays and lets you place up to four of them on a single PCB, to control via I2C from your desired microcontroller. Each relay is rated to 40A at 28-380 VAC, so with all four on board you can control some serious power all from the Qwiic Connect System. The kit requires no soldering, but there is some minor assembly required to attach the relays to the board and to connect your AC load.

SparkFun Qwiic Button - Green LED

added to your cart!

SparkFun Qwiic Button - Green LED

In stock BOB-16842

The SparkFun Qwiic Button with green LED simplifies all of those nasty worries away into an easy to use I2C device, no solder…


Buttons are an easy and tactile way to interface with your project, but why would you want to deal with debouncing, polling, and wiring up pull-up resistors? The Qwiic Button with built-in green LED simplifies things in an easy to use I2C device! Utilizing our Qwiic Connect System, using the button is as simple as connecting a cable and loading up some pre-written code!

Raspberry Pi Compute Module 3+ Lite

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Raspberry Pi Compute Module 3+ Lite

In stock DEV-16830

This module allows a designer to leverage the Raspberry Pi hardware and software stack in their own custom systems and form f…


The Raspberry Pi Compute Module 3+ Lite contains the guts of a Raspberry Pi 3 Model B+ (the BCM2837 processor and 1GB LPDDR2 RAM). This module allows a designer to leverage the Raspberry Pi hardware and software stack in their own custom systems and form factors. In addition, this module has extra IO interfaces over and above what is available on the Raspberry Pi model A/B boards, opening up more options for the designer.

Kitronik MI:power Board

added to your cart!

Kitronik MI:power Board

In stock DEV-16824

The MI:power board adds portability to your project. A buzzer and 3V coin cell holder is connected to the 3V, GND and P0 conn…


The MI:power board for the BBC micro:bit brings real portability to your wearable projects. The stylish, lightweight PCB is designed to fit snugly against the BBC micro:bit and features a built-in buzzer and 3V coin cell holder. When assembled, the MI:power board is connected directly to the 3V, GND and P0 connections on the micro:bit. The 3V and GND connections provide power to the micro:bit and the built-in buzzer is connected to P0, which is the default output pin when using the audio functions in the Block Editor software.

Solar Panel Charger - 10W

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Solar Panel Charger - 10W

In stock PRT-16835

This is a portable, slim, lightweight solar panel charger with 10 watts of power and a standard USB connection port.


Have a project that needs some good power? Do you like free power provided by our friend, Mr. Sun? This solar panel charger is a lightweight, ultra thin (2mm), and affordable power solution. This panel comes with a 5V USB connection port. The panel is capable of 10 watts in the open sun with a peak power output around 6V at 1700mA.

That's it for this week! As always, we can't wait to see what you make! Shoot us a tweet @sparkfun, or let us know on Instagram or Facebook. We’d love to see what projects you’ve made!

Never miss a new product!

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Chaac weather station

An update on Chaac weather station project we covered previously:

With this latest redesign, I made a few more changes. First of all, I decided I would no longer be afraid of LoRa and put in a LoRa radio module. This will, with the right firmware, allow for standalone operation using LoRaWAN and The Things Network. It will also allow for much longer range, with its lower 900MHz frequency, with some slightly higher power consumption. I can continue using it with my Raspberry Pi point-to-point setup as well.

More details at Project files are available on GitHub.

Check out the video after the break.

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Travel the world with a retro musical phone

This rotary phone features a built-in Raspberry Pi that communicates with (a musical time machine) and an Arduino working behind the map to control the selection of the country. Just pick up the phone, choose a country and a decade, and listen to some great music!

How does it work?

The Raspberry Pi:

  • Plays music through
  • Detects when the handset is picked up/put down
  • Detects the numbers that are dialled in

The Arduino:

  • Detects which country is selected on the map (via jack connectors)
  • Sends the info to the Raspberry Pi over serial

We saw this project on and loved how maker Caroline Buttet dug into the finer detail of an old-fashioned rotary phone’s pick-up/put-down mechanism, as well as how the phone knows which numbers you’re dialling. She goes into more detail about that aspect in the second build video, above.

An audio jack being plugged into a world map mounted on a board

Some countries have a jack pin – this is how you select the music

Other bits you’ll need

As well as a Raspberry Pi 4 and Arduino UNO, you’ll need a world map (obviously) and something to mount it on which can be drilled into. This is because the jack pins you can see in the image above need to poke out of different countries.

Caroline’s grandma donated the old rotary phone she used for this project. You should be able to pick one up from a second-hand shop or, if you can get a new handset made in the retro style online.

The shopping list for this build also includes: jumper wires; audio/video cable assembly; LED, breadboard; jack socket 3-pin; resistors

A simplified visual representation of how everything works

In her original post, Caroline explains in detail how to connect the rotary phone’s switches to the pins on your Raspberry Pi, how to build in audio sockets on the board you glue your map to, how to run the necessary Python script from the command line, and what a Chrome extension to use to make work with your Raspberry Pi.

The Raspberry Pi inside the rotary phone

And yes, Caroline is one of those most magical of makers who deposits all the code needed for this build on GitHub!

And here’s the Arduino mounted onto the back of the map, with the audio jacks taped up to the holes drilled into different countries

The post Travel the world with a retro musical phone appeared first on Raspberry Pi.

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EFF Launches Searchable Database of Police Agencies and the Tech Tools They Use to Spy on Communities

Atlas of Surveillance Shines Light on Deployment of Cameras, Drones, and More

San Francisco—The Electronic Frontier Foundation (EFF), in partnership with the Reynolds School of Journalism at the University of Nevada, Reno, today launched the largest-ever collection of searchable data on police use of surveillance technologies, created as a tool for the public to learn about facial recognition, drones, license plate readers, and other devices law enforcement agencies are acquiring to spy on our communities.

The Atlas of Surveillance database, containing several thousand data points on over 3,000 city and local police departments and sheriffs' offices nationwide, allows citizens, journalists, and academics to review details about the technologies police are deploying, and provides a resource to check what devices and systems have been purchased locally.

Users can search for information by clicking on regions, towns, and cities, such as Minneapolis, Tampa, or Tucson, on a U.S. map. They can also easily perform text searches by typing the names of cities, counties, or states on a search page that displays text results. The Atlas also allows people to search by specific technologies, which can show how surveillance tools are spreading across the country.

Built using crowdsourcing and data journalism over the last 18 months, the Atlas of Surveillance documents the alarming increase in the use of unchecked high-tech tools that collect biometric records, photos, and videos of people in their communities, locate and track them via their cell phones, and purport to predict where crimes will be committed.

While the use of surveillance apps and face recognition technologies are under scrutiny amid the COVID-19 pandemic and street protests, EFF and students at University of Nevada, Reno, have been studying and collecting information for more than a year in an effort to, for the first time, aggregate data collected from news articles, government meeting agendas, company press releases, and social media posts.

"There are two questions we get all the time: What surveillance is in my hometown, and how are technologies like drones and automated license plate readers spreading across the  country?" said Dave Maass, a senior investigative researcher in EFF's Threat Lab and a visiting professor at the Reynolds School of Journalism. "A year a half ago, EFF and the Reynolds School partnered to answer these questions through a massive newsgathering effort, involving hundreds of journalism students and volunteers. What we found is a sprawling spy state that reaches from face recognition in the Hawaiian Islands to predictive policing in Maine, from body-worn cameras in remote Alaska to real-time crime centers along Florida's Gold Coast."

Information was collected on the most pervasive surveillance technologies in use, including drones, body-worn cameras, face recognition, cell-site simulators, automated license plate readers, predictive policing, camera registries, police partnerships with Amazon’s Ring camera network, and gunshot detection sensors. It also maps out more than 130 law enforcement tech hubs that process real-time surveillance data. While the Atlas contains a massive amount of data, its content is only the tip of the iceberg and underlines the need for journalists and members of the public to continue demanding transparency from criminal justice agencies. Reporters, students, volunteers, and watchdog groups can submit data or share data sets for inclusion in the Atlas.

“The prevalence of surveillance technologies in our society provides many challenges related to privacy and freedom of expression, but it's one thing to know that in theory, and another to see hard data laid out on a map," Reynolds School Professor and Director of the Center for Advanced Media Studies Gi Yun said. "Over a year and a half, Reynolds School of Journalism students at the University of Nevada, Reno have reviewed thousands of news articles and public records. This project not only informs the public debate but helps these students improve their understanding of surveillance as they advance in their reporting careers."

For the Atlas:

For more on street-level surveillance:

Senior Investigative Researcher
UNR Reynolds School Professor and Director of the Center for Advanced Media Studies

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Linkdump: May 2020

Map in coronal frame with bird pertching

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Switching to Different Relays

SparkFun will soon be releasing a solid state relay board! We currently offer several boards with mechanical relays, and due to demand we are releasing a board with solid state relays. What is a relay used for and which one would work best in your project? Join us as we discuss relays!

Relay Kit

What is a relay and what is a switch?

In general, a relay is an electrically-actuated switch. A switch is characterized by its ability to connect or disconnect a conductive path of a circuit. Switches are further characterized by their number of poles (a contact point) and throws (a specific contact-to-contact connection). A relay allows for the disconnection or connection of a circuit without having to manually do so, like pushing a power plug into an outlet.

We see here a diagram of what is called a SPDT (single pole, dual throw) switch. There is one contact point at a time (the pole) and two configurations for contact-to-contact connections (throws).

Mechanical Switch

A SPDT switch

You are probably familiar with push button switches or the light switch on your wall - both take physical effort and time to actuate. Flipping a light switch can often take upwards of 1000 milliseconds, assuming you are even close to it!

Relays can be a great and safe way to control higher power systems with an isolated low power signal, and quickly disconnect or connect circuits. There are several different types of relays and their functions are slightly different.

Mechanical relay

The most common relays are known as mechanical relays or electro-mechanical relays (EMR).

A typical mechanical relay sends current through an inductor magnet that pulls a flexing conductive plate from one switch contact to another. We can see in this example below the inductor and its relation to the switch. The magnetic field generated by current going through the coil pulls the throw from one pole to another.

SPDT Relay
An inductor using magnetic force throw a switch

In general, mechanical relays are designed for higher currents and have slower switching speeds, typically around 50 milliseconds - about 20 times faster than flipping that light switch ourselves. They are relatively simple in their construction, so they are often less expensive and easier to replace. They create the familiar relay clicking noise when the conductive contact moves from one pole to another.

There are several issues that arise from using an inductor that need to be addressed in designs using relays:

  • Due to having physically moving parts, they are more likely to suffer damage over time.
  • When changing relay states, one must carefully apply voltage across the leads on the inductor. Too much voltage can result in damage to the inductor, and too little will not be enough to properly move the conductive plate, resulting in either no switching or erratic behavior.
  • There is an audible clicking as the relay switches.
  • They are more prone to interference - either magnetic or vibration.
  • Another issue that arises comes from removing the current from the inductor, which is acting as an inductor. This sudden collapse of the magnetic field can cause a surge in voltage and current that will damage the inductor and nearby components. If you are curious about preventing these sudden spikes from causing havoc, I recommend looking at the flyback diodes on our relay boards.

Solid state relay (SSR)

Solid State Relay

Solid state relays do not have moving parts, as the name implies they exist in a solid state. They are intended to be used in the same way as mechanical relays but have a number of important differences. They connect or disconnect a circuit by applying a separate voltage across a semiconductor junction, often an opto-isolator or a MOSFET, instead of using an inductor to physically move a component. This allows a low power signal to turn on a high power system with just a couple mA’s, while being able to isolate the control side of the relay from the switching side.


In the orange box we can see the use of an opto-isolater to connect or disconnect an isolated circuit.

Solid state relays work well for a wide range of currents and have extremely fast switching times, often around 50 nanoseconds - about 20,000,000 times faster than flipping that light switch ourselves.

Solid state relays are more complicated in design, and require more sensitive components. There are a few drawbacks to using a SSR:

  • They are often much more expensive than mechanical relays.
  • They are very difficult to repair due to their complex assembly.
  • There is no audible clicking.

Which is best?

Which relay is right for your project depends largely on the needs of the project. Mechanical relays offer a low-cost way to remotely control a circuit using roughly 25 percent of the max control voltage rating of the relay.

Solid state relays offer a reliable and fast way to connect and disconnect a circuit using only miliAmps at a higher price point. They are less likely to be negatively effected by nearby magnetic interference or vibrations.

We are starting to see a shift toward solid state relays as their price comes down. Their solid state nature means fewer mechanical errors and increased longevity of the part. This is similar to the change in hard disk drives (HHDs) and solid state drives used in memory storage.

We will be releasing our own SSR boards soon, ready to be actuated at your heart's content. Check back soon to get your own!

What are you using your relays for? Is there any love for reed switch relays these days? Let us know what you think in the comments.

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FPGA Softcore SoC shootout #FPGA

Just another electronics blog publishes a FPGA Softcore SoC shootout.

I have a few requirements any CPU must meet:

1. There must be a GCC or LLVM compiler available
2. No vendor specific CPU, a CPU should run on all FPGA’s
If possible, a simple ready to go SoC with Uart, Timer and GPIO is nice, but no requirement.

And the following FPGAs made the cut:

  • VexRiscv
  • LEON3
  • PicoRV32
  • Neo430
  • ZPU
  • Microwatt
  • S1 Core
  • Swerv EH1

I liked the Vexriscv, LEON3 and NEO430 the most in terms of usability. None of them were perfect. Vexriscv is very flexible, but lacks documentation in some areas, LEON3 probably works perfect with a commercial license and the NEO430 lacks a debugger. But all in all, those three seem the best choices in my opinion if you need a CPU for an FPGA project.

See the entire comparison in the article here.

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Autonomous Riding Lawnmower – Phase One Update

Jesse Brockmann is a senior software engineer with over 20 years of experience. Jesse works for a large corporation designing real-time simulation software, started programming on an Apple IIe at the age of six and has won several AVC event over the years. Jesse is also a SparkFun Ambassador. Make sure you read today's post to find out what he'll be up to next!

This is the second part of a multi-post series. If you would like to start from the beginning click here to see part one.

I would first like to respond to some comments I received on this project. I support and encourage the right to repair, and I can understand why people are upset with the current situation with newer equipment from John Deere or other companies. This mower was produced in a very different era and was very well documented by the owner's manual. For example, it included a complete circuit diagram with standard maintenance procedures and ways to fix common issues that an owner may have.

I’ve been making good progress on the mower project and I thought it was time for an update. A motor mount was fabricated and sprocket attached to the steering wheel. Size #25 chain is being used to connect the geared motor to the steering sprocket. The motor mount is notched to allow the chain tension to be adjusted.

Steering Sprocket

I also bought a linear actuator to control the brake/clutch mechanism. The linear actuator has a built-in potentiometer to provide feedback. This feedback will be used to set the end points for the actuator, so damage is not done to the brake pedal. The actuator has six inches of travel and 55 lbs of force for a margin of safety. As you can see, the mounting worked out well, as an existing hole was used and a threaded rod was run through that hole to mount the end of the actuator on a custom fabricated bracket.


For the throttle, a servo was attached to the side of the tractor using a custom fabricated bracket. From the servo horn, a linkage was used to connect to the carburetor. This allows for full control of the throttle including the ability to kill the engine at very low throttle and choke for startup.


Another custom mount was fabricated to shift the mower between second gear, neutral and reverse. This completes the four major control systems required for the mower.


However, an extra safety system was added that allows the mower to be killed by shorting a wire that is part of the ignition system. This wire was routed up to the location where the controller will sit. The wire attaches to a relay on a normally closed connection. This means when the relay is not energized, the engine cannot run. This is a last line of safety in case the controller fails or power is lost.

Ignition System

A new circuit breaker was added to power the new control systems and wires run to the location of the controller. A fuse block provides power to the various circuits, and switches are used so the controller can be powered but leaves the motors disabled for testing.

Circuit Breaker

I decided to do some testing before all the systems were ready; here is the result of my testing late last fall.

The project sat over the winter, but I started again this spring. The various systems I described above were fabricated and tested manually without the controller. I then started to work on the code for the overall system. The system will have the following modes: INIT, START, STOP, RUNNING, FAILSAFE, MANUAL and KILL.

Here is a table with the various modes and sub-systems. Any software connected to hardware should have various MODES and some rigid guidelines to avoid any catastrophic issues. This is no time to slack on your code!

Mode Brake Throttle Shifter Steering Kill Relay
RUNNING Controlled Controlled CONSTANT Controlled ON
Manual Controlled Controlled Controlled Controlled ON/OFF

The FAILSAFE and KILL modes are used if some failure occurs. Depending on the nature of the failure, a determination is made if it’s a FAILSAFE or KILL failure. Loss of radio contact is a FAILSAFE failure, but any communication failure with the controllers is a KILL failure. Other failure modes will be added as needed, such as low input voltage, temperature too high on some sub-system, over current on steering motor controller, etc.

I think most of these modes are easy to explain. MANUAL mode exists for testing, and will allow for testing in ways the other modes will not allow. My end customer for this mower will not have access to this mode.

From each of the above modes, only certain other modes can be intentionally reached except for KILL. Here is what switching to different modes looks like.

INIT -> STOP (Automatic)

FAILSAFE mode is possible from any mode other than FAILSAFE or KILL, but the controller decides when it is activated. If the FAILSAFE condition is resolved, then switching to STOP is allowed.

At this point, all that is left is to test the above logic in standalone mode off the mower, and make 100 percent sure that the above logic table is followed and no crashes or weird behaviors occur. I’ve certainly found and fixed issues already, such as the brake not being engaged when switching from RUNNING to STOP. This would mean I could not stop the mower without switching to RUNNING mode again and that could lead to a runaway mower.

Once standalone mode is working, I will start testing the various control systems in isolation and then finally test the entire system on the mower. Please stay tuned for the final write-up on this project (hopefully in a month or two), and hear details about my next big project: a remote control/autonomous electric go-kart!

As a thank you for reading this far, I would like to let you know I have a special promo code you can use to get 10% off any SparkFun Original product. Just use ORIGINALRED2020 during checkout. This code is good through the end of 2020, but can only be used once per customer. Thanks for reading - I hope I can start attending STEM shows next year and show off my hard work on this and other projects I have been working on.

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