Monthly Archives: July 2021


via SparkFun: Commerce Blog

Welcome back everyone - we're here with another week of new products! We start off with a new Qwiic board that just recently graduated from SparkX to receive a full production run and support: the Qwiic EEPROM Breakout, which adds easily accessible memory to your next project! Following that we have the new ESP32-C3 Module, along with a mini development board that utilizes it. Espressif has really outdone themselves with these. Let's dive in and take a closer look at all of our new products.

Will you be our date to the EEPROM?

SparkFun Qwiic EEPROM Breakout - 512Kbit

SparkFun Qwiic EEPROM Breakout - 512Kbit


The SparkFun Qwiic EEPROM Breakout is a simple and cost effective option to add some extra storage space to any project. With 512 kilo-bits (or 64 kilo-bytes) of storage, this product is great for any microcontroller that doesn't have any EEPROM storage space, like the SAMD21. You can use the Qwiic EEPROM for storing data like GPS waypoints and other user settings that need to be maintained between sketch uploads. The SparkFun Qwiic EEPROM has three address jumpers, allowing for up to eight EEPROMs on one bus. All communication is enacted exclusively via I2C, utilizing our handy Qwiic system (as the name implies). However, we still have broken out 0.1" spaced pins in case you prefer to use a breadboard.

ESP32-C3 WROOM Module - 4MB (PCB Antenna)

ESP32-C3 WROOM Module - 4MB (PCB Antenna)


The Espressif ESP32-C3 is the next version of the popular ESP32 Bluetooth® and WiFi enabled module. This module features a single core, RISC-V-based processor with WiFi and Bluetooth LE 5.0 radios built into the SoC. The module features a PCB antenna and castillated plated pins for surface-mount affixment. This variation has 4 MB of on-board SPI flash and is the 85 °C temperature tolerant version.

ESP32-C3 Mini Development Board

ESP32-C3 Mini Development Board


The ESP32-C3 Mini Development Board is an entry-level development board based on ESP32-C3-MINI-1, a module named for its small size. This board integrates complete Wi-Fi and Bluetooth® LE functions.

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! Please be safe out there, be kind to one another, and we'll see you next week with even more new products!

Never miss a new product!

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Combining Art and Technology for Interactive Learning, pt. II

via SparkFun: Commerce Blog

The Hong Kong Heritage Museum, known as one of Hong Kong’s best “lesser known” attractions, houses a number of permanent exhibits as well as ever changing special and touring exhibits, plus an interactive Children’s Discovery Gallery, all covering art, culture and history. One of the museum’s permanent exhibits, titled “Hong Kong Pop 60+,” is where this new installation is housed. If you recall, Alexson was using using the SparkFun Simultaneous RFID Reader, along with three Bare Conductive Touch Boards, to create an interactive book using projection mapping to bring the pages to life. Take a look at a little bit of the project in action on Alexson's Twitter page.

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The book as it is now displayed in the “Hong Kong Pop 60+” exhibit in the Hong Kong Heritage Museum.

In the original design, each page had an embedded RFID tag, shielded on one side with aluminum foil to prevent false reads. However, concerned not only for false positives but false negatives as well - that is, the reader not picking up the tag on a page turn - Alexson decided to double up, using two RFID tags on each page for redundancy.

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Alexson doubled up on RFID tags to eliminate missed events. (Photo credit: Alexson Chu)

Another adaptation from the initial design came about due to concerns over wear and tear. As an interactive part of a permanent exhibit, Alexson knew that this book would be subjected to possibly thousands of page turns, some of them perhaps not as gentle as one would hope. For this reason, the copper tape used for prototyping was replaced with flexible PCBs.

“[For] the ‘touch’ part at the end we switched from using copper tape and conductive ink to flexible PCB for extra robustness,” Alexson told me.

For a project that is going to be handled six days a week with no end date in sight, this is a smart move, and a great example of a designer making adjustments based on the needs of a project and its environment.

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Needing both flexibility and strength, the move was made from copper tape and conductive ink to flexible PCBs. (Photo credit: Alexson Chu)

One thing that Alexson noticed and shared with me was the fact that the Simultaneous RFID Reader would get exceedingly hot when running for long periods of time. As this project will be running for at least eight hours a day, six days a week, this could eventually lead to thermal shutdown, a disappointing museum exhibit, and a curator who’ll think twice when it comes time to find someone to create their next installation. To help keep things (relatively) cool, a heat sink was added, along with a high cfm fan. This is also a good time to emphasize the importance of considering your project’s enclosure. Some chips, while able to run a multitude of high-level tasks, do so with the cost being extremely high operating temperatures. Always make sure that you have sufficient air flow across your project, even if it means creating the space for a heat sink, fan, or as is the case with this project, both.

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”Any sufficiently advanced technology is indistinguishable from magic.” ~ Arthur C. Clarke

While most of us probably won’t get the chance to visit this exhibit in person, just seeing this project, its seamless integration of multiple input and display technologies, and the final product, should be inspiration enough to get the creativity flowing in most of us. If by chance you do find yourself in Hong Kong, you can enjoy this project and many other historical, artistic, cultural and educational experiences at the Hong Kong Heritage Museum.

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Top 10 Design Mistakes to Avoid When Developing your Electronic Hardware Product

via SparkFun: Commerce Blog

For the next few weeks, John Teel, Founder of Predictable Designs, will be sharing a series of guest blog posts with us, helping readers gain insights into strategy, design thinking, and how to get great product ideas to market. John is an electronics design engineer, serial entrepreneur and blogger, who now focuses on helping hardware entrepreneurs, startups and small companies through his Hardware Academy program. Check out his website for more insights and to learn more.

When developing and selling a new electronic hardware product there are often mistakes made that cost you both money and time to market. I’m going to share with you some of the most common mistakes made when developing a new electronic product, so you can hopefully avoid them during your own product development. This list includes technical errors with your product’s electronics design and mistakes made with the plastic enclosure design in regards to manufacturability. I also include some more general product development mistakes often made by first time developers and entrepreneurs.

#1: Failing to Design for Manufacturing

People tend to underestimate the complexity of developing a new physical product, and they underestimate the complexity of manufacturing it even more. For many products it takes nearly as much time, sometimes even more, to get manufacturing up and running as it does to develop the product. Manufacturing setup can also cost as much or more than all your development costs. It is essential that manufacturability be a primary consideration during the entire product design process. This process is called Design-For-Manufacturing (DFM). Nothing will slow down your path to market more than designing a product that can’t be efficiently manufactured.

Three stacks of green PCBs
To simplify manufacturing, implement design for manufacturing practices as early as possible.

The old way of thinking was that engineers develop a product, and then pass it on to a manufacturer (or the manufacturing department for big companies) who would then figure out how to actually make it. There was little to no interaction between engineering and manufacturing. But that’s a horrible way to develop products, which is why successful companies have abandoned this process. It’s much better to develop a product with manufacturing in mind from the beginning. For example, a simple design change can have a huge impact on making the product easier and faster to manufacture. For most products, two of the primary manufacturability requirements are that the electronics be designed for testability, and the enclosure be designed for injection molding.

#2: Incorrect Design of Wireless Circuits

If the product has any wireless functionality, the PCB layout for any RF (radio-frequency) portions is super critical. Unfortunately, it’s done wrong more often than right, so watch this one very closely. For example, for maximum power transfer between the transceiver (transmitter/receiver) and the antenna their impedance must be matched. This means two things are required.

First is a proper transmission line connecting the antenna and the transceiver. This transmission line is fabricated on the PCB specifically for carrying microwaves (high frequency radio waves). There are two common types of transmission lines used on PCB designs: a microstrip and a coplanar waveguide. A microstrip is a conducting strip separated by a dielectric layer from a ground plane beneath it. A coplanar waveguide is similar to a microstrip except that it also adds another ground plane beside the conducting strip on the same layer. Of the two styles, the coplanar waveguide is the most frequently used.

In most cases the transmission line needs to be designed with a 50 ohm impedance for maximum power transfer with the antenna. Don’t confuse this impedance specification with the simple resistance of the line. The 50 ohm impedance refers to the complex impedance from the transmission line to the surrounding ground planes. I suggest you use a free tool called AppCad from Broadcom for calculating the proper transmission line dimensions.

In addition to using a 50-ohm transmission line, it’s also necessary to usually add some type of LC matching circuit like a pi-network. This allows fine tuning of the antenna impedance for optimum matching and maximum power transfer.

Board held by tweezers
Proper layout of an RF transmission line is critical. Use of a pre-certified module is a more simple option.

One of the best ways to avoid these complexities, as well as reduce the cost to get your product certified, is to instead use a pre-certified module for any wireless functions.

For most wireless functions there are two general design strategies: custom build your own circuit using the appropriate microchips, or use a pre-certified module with proven functionality. Designing your own wireless RF circuit is complex. In fact, it is likely the most complex type of circuit to properly design. Honestly, odds are it won’t be done correctly. You should expect to need multiple prototype iterations to get it just right. The other downside to a custom design is it will add at least $10,000 to your FCC certification costs. Use of a module may cut into your profit margin a bit, but maximizing margins should never be your initial priority.

Yes, you need to understand in advance what your profit margins will be once you reach manufacturing at large scale. But when first starting out your priority should be reducing your cost to market, not maximizing your profits. Profit comes later.

#3: Waiting Too Long to Estimate Manufacturing Cost

This is a big one. Successful tech companies always know approximately how much a product will cost to manufacture well before they begin full development. Otherwise, how can they know the product is worth developing?

If you’re not a billion dollar tech company, the odds are you will first get your product fully designed. Once you have the final prototype, and you are ready to start manufacturing, then you will finally estimate how much the product will cost to manufacture. What happens, though, if you discover that your product is going to cost more to manufacture than you expected? You could increase you sales price target, but that obviously has negative consequences.

You could also make some redesigns to lower the manufacturing cost. But wouldn’t it have made more sense to just design it right the first time? For understandable reasons, many people think that you have to fully develop a product before you can accurately calculate the manufacturing cost. That is absolutely untrue. With the right experience, it is possible to accurately estimate the manufacturing cost for just about any product. This can happen well before any PCB layout or 3D modeling occurs.

#4: Insufficient Width for High-Current PCB Traces

If a PCB trace will have more than roughly 500 mA flowing through it, then the minimum width allowed for a trace probably won’t be sufficient. The required width of the PCB trace depends on several things including the thickness of the trace (copper weight), and whether the trace is on an internal or external layer. For the same thickness, an external layer can carry more current for the same width than an internal trace, because external traces have better air flow allowing better heat dissipation.

PCB traces on a chalkboard
Any PCB traces carrying more than 500 mA will need to be made wider than the minimum trace width.

The thickness depends on how much copper is being used for that conducting layer. Most PCB manufacturers allow you to choose from various copper weights from 0.5 oz/sq. ft to about 2.5 oz/sq. ft. If preferred, you can convert the copper weight to a thickness measurement such as mils. When calculating the current-carrying capability of a PCB trace, you must specify the permissible temperature rise for that trace. Generally, a 10 C rise is a safe choice, but if you need to squeeze down the trace width more you can use a 20 C or higher allowed temperature rise. Although the calculations for trace width are pretty simple I usually recommend using a trace width calculator.

#5: Not Getting a Design Review

If you don’t get an independent design review of your product before you prototype it then you may be throwing money away. It doesn’t matter how good an engineer may be, nobody is perfect, and all engineers make mistakes. Getting custom prototypes made (whether it’s the electronics PCB or the product’s enclosure) isn’t cheap. The more prototype iterations you require, the more it will cost in total. It will also take longer to develop and bring the product to market.

One of the best ways to reduce the number of prototype iterations required is to get a second opinion called a design review. Successful tech companies always require their engineers to hold design reviews to seek feedback from as many other engineers as possible. Unfortunately, many entrepreneurs, startups and small companies make the mistake of completely skipping this critical step. That’s fine if you have the skills to sufficiently review the design yourself. But if you had those skills you would have likely just done the design yourself.

#6: Incorrect Use of Decoupling Capacitors

Critical components need a clean, stable voltage source. Decoupling capacitors are placed on the power supply rail to help in this regard. However, for decoupling capacitors to work their best they must be as close as possible to the pin requiring the stable voltage. The power line coming from the power source needs to be routed so it goes to the decoupling capacitor before going to the pin needing a stable voltage.

Also, it’s critical to place the output capacitor for the power supply regulator as close as possible to the output pin of the regulator. This is necessary for optimizing stability (all regulators use a feedback loop that can oscillate if not properly stabilized). It also improves transient response.

#7: Product Enclosure is Not Manufacturable

You’ve spent all of the time and money getting the design of your product’s enclosure to look just right. It’s like a work of art to you, and this required a bunch of 3D-printed prototype iterations to perfect its look and functionality. You finally have the perfect prototype! Now you just need to find a manufacturer to produce them in mass, and you are good to go. Right? What if I told you that your enclosure design is useless and you need to essentially redo the entire thing? That would be horrible to hear, but this is a very common occurrence.

3D printing is very forgiving. You can design and print just about anything your mind imagines. But 3D printing is only for producing a few prototypes. High-pressure injection molding is the technology used for producing plastic parts in high volume. Unfortunately, injection molding is not at all forgiving. It is a technology with many design rules that must be closely followed. These rules can be so major, and so limiting, as to require a major redesign just to make an enclosure manufacturable. When designing your product’s enclosure be sure to consider injection molding requirements from the very beginning.

#8: Incorrect PCB Landing Patterns

All PCB design software tools include libraries of commonly used electronic components. These libraries include both the schematic symbol, as well as the PCB landing pattern. All is good as long as you stick with using the components in these libraries. Problems begin when you use components not in the included libraries. This means the engineer has to manually draw the schematic symbol and the PCB landing pattern.

It’s very easy to make mistakes when drawing a landing pattern. For example, if you get the pin-pin spacing off by a fraction of a millimeter, it will make it impossible to solder the part on the board. A handy trick to avoid this mistake is to print out your PCB layout at a 1:1 scale. Then order samples of all of the various components (mainly the microchips and connectors), and manually place them on your printed PCB layout. This allows you to very quickly verify that all of the landing patterns are correct.

#9: PCB Design Is Not Manufacturable or Too Expensive

A via is a conducting hole in a PCB that connects signals from different layers. The most common type of via is known as a through via because it goes through all layers of the board. This means even if you only want to connect a trace from layer one to layer two, all of the other layers will also have this through via. This can act to increase the size of a board since the vias reduce the routing space on layers not even using the via. A blind via, on the other hand, connects an external layer to an internal layer, and a buried via connects two internal layers. However, blind and buried vias have very strict limitations on which layers they can be used to connect.

Diagram showing which layers of PCB are connected with different types of vias
#1 is a through-via connecting all layers, #2 is a blind via connecting layers 1 and 2, and #3 is a buried via connecting layers 2 and 3.

It’s all too easy to use blind/buried vias that can’t actually be manufactured (or prototyped). To understand the limitations of buried and blind vias you must understand how the layers are stacked to make the PCB. Be warned though that even if you use them correctly, blind/buried vias drastically increase the cost of prototype boards. Many times, their use will double your board cost, although this cost increase will be less significant once you reach higher production volumes. In almost all cases, it is best to avoid the use of buried and blind vias, unless you absolutely must have the smallest PCB design possible.

#10: Incorrect PCB Layout of Switching Regulators

A switching regulator converts one supply voltage to another by temporarily storing energy and then releasing it to the output in a controlled fashion. The storage elements used are inductors and capacitors. Compared to simpler linear regulators, switching regulators are extremely efficient and waste very little power. However, they are much more complicated to use correctly. The biggest complexity of using switching regulators is correctly designing their PCB layout. You can’t randomly lay down the components and connect them up. There are strict layout rules you should follow for switching regulators. Fortunately, nearly all datasheets for switching regulators will include a section discussing the proper layout, as well as giving an example of how to do it correctly.


This list could easily be expanded and there are nearly an infinite number of mistakes waiting to be made! Your best bet is to always know about any potential pitfalls well before you actually reach them. This way you can either avoid them completely, or at least be better prepared when they occur.

Hopefully this article helps you eliminate some of these potential mistakes. However, the best way to avoid these types of mistakes is to work with experts. It’s always best if you bring on the necessary experts from the start to help guide you along so you can avoid many of these mistakes before you go to far down a rabbit hole. At the very least, you need to get independent experts to review your design before spending significant money on prototypes or production.

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MicroMod Calendar

via SparkFun: Commerce Blog

In the past I've worked on a few desk gadgets to help me work either more efficiently, or keep track of the time. One of these first projects was a macro keyboard, which I later updated to wireless using Bluetooth. Another was a clock using an ESP32 and our OLED breakouts. Like most work places across the world, once the pandemic started, we relied even more on email and virtual meetings to continue planning and releasing products which increased the importance of staying on top of my calendar and email.

To try and stay organized, I keep my mail and calendar apps open and check them throughout the day. The problem though is as I'm working, I have windows open on top of those apps as I read through a datasheet, update schematics, work on a board design, write code, etc., and I have to rely on the notifications that pop up, which don't always get my attention. I thought that when I upgraded to two monitors it would be enough, but unfortunately it wasn't, and a third monitor isn't really an option. So instead, I drew inspiration from my desk gadgets and thought that they might like a new friend that I call the MicroMod Calendar.

MicroMod Calendar

It uses two boards, the MicroMod Input and Display Carrier Board, and the MicroMod ESP32 Processor board. It connects to my Google account through a script, creates a text output with all of my meetings for the day from the calendar, and checks my email to see how many unread messages I have to display on the 2.4" TFT screen.

Script Output

Since the ESP32 is connected to the internet, I also get the current time using the Network Time Protocol, which allows the board to show when my next meeting is. Most of the time my computer will give me a 10-minute warning, but because Cortana likes to hide those alerts on me from time to time, I used the APA102 LEDs to always give me alerts when a meeting is 10 minutes out, five minutes out, and starting now, by flashing the LEDs green, yellow and red.

LED Alerts

As I was working on the software, I realized that it could also be really useful not just on my desk, but my lab bench as well where my back is always facing my desk. And while my desk already has a clock that I made sitting on it, my bench does not, so I want something a little different for each location.

On this first display, I show the time, what my next meeting is, and how long until it starts. Below in slightly smaller text are future meetings, along with their start times to help plan out my day. Finally at the bottom, I show how many unread emails are sitting in my inbox.

Calendar View 1

On the second display, I removed the time, which allowed me to increase the text size a bit, and give a little more space for better readability.

Calendar View 2

To switch between the two displays, I made use of the 5-way switch on the Input and Display - left/right switches between the displays, up/down changes the backlight brightness, and the center button flips the display 180 degrees, which allows for the USB cable to come out on either the left or right side of the case. All of these settings get saved to memory, so if the board resets or loses power it maintains the same settings.

For the past week or so I've had the MicroMod Calendar set up trying to spot any bugs in the code, and make a couple tweaks here and there. Mainly it was adjusting the brightness of the LEDs that they could get my attention without leaving me seeing spots. But similar to my macro keyboard, this has been a really handy tool to have on my desk, and wish I made it sooner. If you're interested in building your own, you can check out the GitHub page, which has everything you'll need to make your own from the ESP32 code, Google Apps Script, and 3D models that I made for the case.

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FPGA comes to Thing Plus with QuickLogic

via SparkFun: Commerce Blog

Hello and welcome back to another exciting Friday Product Post! This week, we are thrilled to finally reveal that the SparkFun QuickLogic Thing Plus is available for everyone who didn't back the board in March when we originally announced it on Crowd Supply. This is an extremely powerful and reliable FPGA board in a Feather-footprint, and we are sure that it will make a great resource for anyone looking to get into the world of Field Programmable Gate Arrays. Next up, we have four different versions of Carbide3D's Shapeoko 4 XXL and four versions of their Shapeoko 4 XL. To round out the day we have some new resistors. People always need resistors, don't they? Now, let's jump in and take a closer look at all of our new products!

A new FPGA in a familiar package!

SparkFun QuickLogic Thing Plus - EOS S3

SparkFun QuickLogic Thing Plus - EOS S3


The SparkFun QuickLogic Thing Plus EOS™ S3, is a small form factor system ideal for enabling the next generation of low-power Machine Learning-capable Internet of Things (IoT) devices. The QuickLogic Thing Plus is powered by QuickLogic’s EOS S3, the first eFPGA-enabled Arm Cortex©-M4F MCU to be fully supported with Zephyr RTOS and FreeRTOS. Unlike other development boards based on proprietary hardware and software tools, the QuickLogic Things Plus is based on 100% open source hardware, compatible with the Feather form factor, and is built around 100% open source software (with support for FreeRTOS, Zephyr, nMingen, Docker and SymbiFlow).

Shapeoko 4 XXL - Hybrid Table, with Router

Shapeoko 4 XXL - Hybrid Table, with Router


This is the Shapeoko 4 XXL, nearly double the cutting area of the Shapeoko 4 Standard! The Shapeoko is a 3-axis CNC Machine kit that allows you to create your 2D and 3D designs out of non-ferrous metals, hardwoods and plastics. The Shapeoko 4 XXL is designed to be affordable enough for any shop and powerful enough to do real work. Don’t let the size intimidate you! This is an entry-level CNC machine designed for hobbyists, artists and fabricators!

The Shapeoko 4 XXL is offered in four different versions: with Hybrid Table and router, with Hybrid Table but without router, without hybrid table and router, and without hybrid table but with router.

Shapeoko 4 XL - Hybrid Table, with Router

Shapeoko 4 XL - Hybrid Table, with Router


The Shapeoko 4 XL is nearly identical to the XXL version above and still features double the cutting area of the Shapeoko 4 Standard! While the cutting area of the XXL is 838.2 mm x 838.2 mm x 101. 6mm (33 in x 33 in x 4 in), the XL has a cutting area of 838.2 mm x 444.5 mm x 101.6 mm (33 in x 17.5 in x 4 in). So, if you are looking for a slightly smaller cutting area at a lower cost, the XL might just be the right option for you!

The Shapeoko 4 XL is also offered in four different versions: with Hybrid Table and router, with Hybrid Table but without router, without hybrid table and router, and without hybrid table but with router.

Resistor 220 Ohm 1/4th Watt PTH

Resistor 220 Ohm 1/4th Watt PTH


This is a 220 Ohm, 1/4th Watt, +/- 5% tolerance PTH resistor, commonly used in breadboards and perf boards. We've opted for a new and more breadboard-friendly lead thickness.

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! Please be safe out there, be kind to one another, and we'll see you next week with even more new products!

Never miss a new product!

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Behind the Scenes: Making a SparkFun Board

via SparkFun: Commerce Blog

Every so often we like to share what it takes to build a board from beginning to end. When our friends at QuickLogic asked us to show what it took to produce the new SparkFun QuickLogic Thing Plus FPGA board (announced and backed in March on Crowd Supply and releasing tomorrow!) we thought it would be a fantastic opportunity to put together a video showing you what happens on our production floor on a daily basis! This was a fun board to design and build, and we're excited to share a look at the steps we take to turn a PCB into an FPGA.

Making the SparkFun QuickLogic Thing Plus

The SparkFun QuickLogic Thing Plus releases tomorrow, July 23rd. This board is powered by QuickLogic’s EOS S3, the first eFPGA-enabled Arm Cortex©-M4F MCU to be fully supported with Zephyr RTOS and FreeRTOS. Unlike other development boards based on proprietary hardware and software tools, the QuickLogic Things Plus is based on 100 percent open source hardware, is compatible with the Feather form factor, and is built around 100 percent open source software (with support for FreeRTOS, Zephyr, nMingen, Docker and SymbiFlow). Come back tomorrow to order yours!


FPGA chip


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