Monthly Archives: November 2018

New product: STSPIN820 Stepper Motor Driver Carrier with 1/256 microstepping

via Pololu Blog

We have yet another new stepper motor driver carrier in our popular 16-pin, 0.6″ × 0.8″ form factor, this time for STMicro’s STSPIN820, which offers 1/256 step microstepping! ST actually has their own similar evaluation board, the EVALSP820-XS, but the STSPIN820 chip has a non-inverted Enable input, which is inverted compared to most other stepper motor driver ICs out there, and they expose the pin that way on their version of the board. We have thoughtfully added a transistor-based inverter so that our board is more likely to work as a drop-in replacement (or upgrade!) for the stepper driver boards you already have. In our tests, the Pololu carrier supported a substantially higher maximum current than the ST eval board (around 900 mA compared to 720 mA, probably due to our board having four layers vs. two layers for the ST eval board), and as of this writing (27 November 2018), our board is also priced lower.

You can see the full schematic for all the details (this schematic is also available as a downloadable pdf (109k pdf)):

Schematic diagram of the STSPIN820 Stepper Motor Driver Carrier.

With our release earlier in November of compact carriers for Toshiba’s TB67S249FTG and TB67S279FTG stepper motor drivers, we now offer ten different stepper motor driver modules in this compact size:


A4988
(original)

A4988,
Black Ed.

DRV8825

DRV8834

DRV8880

MP6500,
Pot. CC

MP6500,
Digital CC

TB67S279­FTG

TB67S249­FTG

STSPIN­820
Driver chip: A4988 DRV8825 DRV8834 DRV8880 MP6500 TB67S279­FTG TB67S249­FTG STSPIN­820
Min operating voltage: 8 V 8.2 V 2.5 V 6.5 V 4.5 V 10 V 10 V 7 V
Max operating voltage: 35 V 45 V 10.8 V 45 V 35 V 47 V 47 V 45 V
Max continuous current per phase:(1) 1 A 1.2 A 1.5 A 1.5 A 1 A 1.5 A 1.1 A 1.6 A 0.9 A
Peak current per phase:(2) 2 A 2.2 A 2 A 1.6 A 2.5 A 2 A 2 A 4.5 A 1.5 A
Microstepping down to: 1/16 1/32 1/32 1/16 1/8 1/32 1/32 1/256
Board layer count: 2 4 4 4 4 4 4 4 4
Special features: high current low-voltage
operation,
high current
AutoTune,
digital current
reduction
high current digital current
control,
high current
Auto Gain Control,
ADMD,
high max voltage
Auto Gain Control,
ADMD,
high max voltage,
high current
128 and 256
microsteps
1-piece price: $5.95 $7.49 $8.95 $5.95 $6.95 $5.95 $5.95 $7.75 $9.95 $7.75
1 On Pololu carrier board, at room temperature, and without additional cooling.
2 Maximum theoretical current based on components on the board (additional cooling required).

As with all of our new products this year, we are offering an introductory special. The first 100 customers that use coupon code STSPIN820INTRO can get up to five units at just $5 each.

Support Raspberry Pi on #GivingTuesday

via Raspberry Pi

Today is #GivingTuesday, a global movement to kick off the charitable giving season.

More than just a computer

When you buy a Raspberry Pi, you’re not only getting a fantastic little computer, but you’re also helping with our charitable educational mission to put the power of computing and digital making into the hands of people all over the world.

The kindness of others

We’re also supported in other ways by very generous people and organizations who believe in what we do. They donate funds, staff time, products, and services to help us achieve our mission. We use all of these resources to give thousands of young people the opportunity to be empowered by technology.

Thousands of young people all over the world learn to code and make things with computers because of your support.

Good news, Americans!

At the end of last year, Uncle Sam granted us nonprofit status, which means we can accept tax-deductible donations from those of you who are in the United States! To celebrate the first-ever #GivingTuesday with US nonprofit status, we’re kicking off a crowdfunding campaign for Coolest Projects USA on the GlobalGiving platform. Your contribution will go towards our annual Coolest Projects event where we celebrate young people who create things with technology. And if you contribute between now and the end of the year, we’ll be eligible for bonus funds offered by GlobalGiving. Our goal is to raise $10,000 for Coolest Projects USA, and we need help from all of you!

Showcasing creativity at Coolest Projects North America

Coolest Projects is a world-leading showcase that enables and inspires the next generation of digital creators and innovators to present the projects that they created at their local CoderDojo, Code Club and Raspberry Jam. This year we brought Coolest Projects to the Discovery Cube Orange County for a spectacular regional event in California.

Those of you in the States can also support us by doing your holiday shopping with Amazon Smile or the 3,000 online stores on Giving Assistant. We’ll get a small contribution for your purchases, and that’ll go toward all the programs that support educators and youth in the United States.

Donate to the Raspberry Pi Foundation

If you would like to make a donation towards our work from anywhere in the world, you can do so via JustGiving or PayPal. Your support for the Raspberry Pi Foundation helps us to train educators face-to-face and online, to provide free educational content for everyone everywhere, to support over 10,000 free coding clubs around the world, to celebrate young creators at high-profile events, and much much more.

Beyond #GivingTuesday

There are plenty of ways to help us achieve our mission all over the world:

No matter what you do, the most important thing we want you to know is how grateful we are to have you in the Raspberry Pi community — we deeply appreciate all of your support.

The post Support Raspberry Pi on #GivingTuesday appeared first on Raspberry Pi.

From the Field: Designing custom PCBs with SparkFun

via SparkFun: Commerce Blog

Over the next few weeks, we’ll be letting some of our customers take over the blog to talk about how they use their favorite SparkFun tools and products in their projects, businesses and everyday lives. The best part? All the SparkFun items on their wishlist will be on sale today only!


I think the first place any aspiring hardware/IoT maker finds themselves (after buying an Arduino or Raspberry Pi) is on the SparkFun website, browsing all the various sensors, breakout boards and tutorials available. I mean the options are endless! From sound, temperature, air quality and pressure sensors; to starter kits for Raspberry Pi, the Inventor’s Kit and Retro Arcade Gaming; to IR Cameras and LiDAR, the possibilities are amazing! And really, there isn’t a better place to begin than buying a sensor or a kit, wiring it all up on a breadboard, connecting it to an Arduino and watching it do something!

Scott’s wishlist (on sale today only!):


Who am I?

As a recent hardware enthusiast, I’ve mainly been working as a software developer and business owner for the last 15 years, and have been working with the latest technologies in my own start-up companies, SMEs and in large, publicly-traded companies. I’ve written software for machine learning (e.g. using Google’s Tensorflow), computer vision (e.g. OpenCV), IoT (Arduino and RPi) and Crypto-currencies (Bitcoin, Ethereum). But a couple of years ago, having just finished a software project and bought my first Arduino, I realised just how much I didn’t know about the hardware side of things! As a firm believer that there’s no better way to learn than to dive in at the deep end, I began working on an open source hardware project to get sensors and Sigfox built into an Arduino-style board, which I called Siguino.

Why the “Siguino” project?

While I did end up buying and using many breakout boards and sample sensor kits, I realized that while it was cool to be able to get a temperature or humidity reading and send it over Sigfox via an Arduino Pro Mini, some SparkFun breakout boards, and a few wires and resistors, it was hard to go from there to what I considered a useful device or product – especially when the result looks like the below (yes, that really was sending temperature and light levels over Sigfox)!

prototype

I wanted to learn how to design my own single board that both already had some useful sensors, and also had the Sigfox comms chip and antenna on board, so once power was supplied it was already a functioning device (re-programmable later on as needed). I also wanted to make this board open source, so others could build on it or learn from it. It was from this that the concept of the Siguino board arose, and ultimately led to a purpose-designed PCB that had all the components I wanted on board.

Siguino component breakdown

Siguino component breakdown

SparkFun resources:

I really could not have completed my open source project without the knowledge and array of products available on the SparkFun site. Here’s just a small sample of the products I used for this project:

  • FTDI Header: an essential piece for programming Arduino Pro Mini (and similar) boards.
  • Kits and sensors for testing: It’s often a very good idea to breadboard up a messy but functional solution (as I did for this project) using the extensive array of sensors available. Couple this with the availability of the underlying Eagle files, and you can essentially build out a working version of the hardware without ever taking out a soldering iron! Specifically, I used the temperature breakout, accelerometer and magnetometer.
  • Adapter boards: When you get a bit deeper into the hardware and you find a particular chip that you want to try but don’t want to to send off a custom PCB for printing yet, definitely grab an adapter board. Most of the major chips you might want to use will likely be in a standard format, and the longer solder pads really help with the hand soldering, especially if you’re not a solder expert (yet!).
  • “How to” guides on Eagle: These are absolutely excellent guides if you want to get into designing your own boards. Anyone enthusiastic enough to get a messy but functional breadboarded concept up and running can go on to design their own PCBs and this series is very informative and easy to follow.
  • GitHub Eagle libs: Having all the SparkFun product schematics and Eagle designs available on GitHub is a very valuable resource. It’s easy to miss the need for a pull-up or pull-down resistor requirement when trawling through datasheets on various chips you might want to use, so to see the schematic of a working board you can test makes things very easy for the new hardware designer.
  • Arduino code libraries: Programming/communicating with the various hardware chips (such as accelerometers, temperature chips, etc.) can involve a lot of searching though the chip datasheets for SPI/I2C/UART settings, commands, etc., so it’s very useful to have sample code written for Arduino for each of the SparkFun modules that sets you up to quickly make use of the hardware.

Product suggestions/improvements:

  • Power analysis: As I was trying to build a ultra-low power board that would last on a battery for months, accurately determining both the constant as well as spiking power profile was very important, and it turns out this is trickier than you might imagine. In the end, it was a specialist board and software I found from Nordic Semi-conductor that worked the best given the micro power requirements I wanted to accurately measure (down to a few microamps), but this was not an easy module to work with, and I think there should be better solutions available for open source hardware building (a RPI shield or something?).
  • RF analysis: Another very difficult thing to assess for the most part when dealing with radio comms (Sigfox, LoRa, Bluetooth, etc.) is whether or not the board is transmitting at the correct frequency and at what power level. Believe me, trying to tailor an RF net for your antenna and attempting to impedance-match your feed line is a dark art! Anyway, most RF analysers are made for professional hardware companies and come at a correspondingly high price point, but I found an independent device that works very well for an affordable price. It would be great to see it as an option on the SparkFun site.
  • More mainstream low level components: I did occasionally find a SparkFun module for a purpose I was interested in (recently, the GPS breakout board, since my next project will incorporate GPS) where the underlying chip (in this case the SkyTraq Venus634FLPx) doesn’t seem readily available from many suppliers. There are a great many GPS chips from different manufacturers, so it would be great if chips that were more readily available were chosen for the SparkFun modules.
  • Further chip adapter boards: I found the adapter boards for the standard SSOP chips very useful, but there is such a vast array of formats for the various chips (with SMD components in particular) from TQFP, QFN, VFLGA, etc., that it would be great of each of these were catered for also.

Final Thoughts

There are a lot of options available at SparkFun, both for the first-time hardware tinkerer (as I was at the start of my project) to the experience hardware engineer, and to those in the former category all I can recommend is to get stuck in building something! Then, if you want to take it further, check out the more in-depth articles on getting started with Eagle schematics I linked to earlier. My own detailed journey from breadboarding to manufactured PCB is available at my website here.


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The age of the Twitter bot

via Raspberry Pi

Despite changes to the process, setting up a Raspberry Pi as a Twitter bot is a fairly easy process. And while many such bots simply share time-lapse snapshots, or change the colour of LEDs across the globe, we know some that fill our timelines with fun, random joyfulness of a daily basis. Here are a few of them:

@DaphneFlap

Celebrated by cat worshippers the world over, Daphne’s Catflap documents the comings and goings of Daphne, the fluffy feline housemate of Kate Bevan. While my own cat is now too big to fit through his catflap, Daphne uses her catflap several times a day, and thanks to the Raspberry Pi connected to it, the catflap does a marvellous job of celebrating Daphne every time she graces us with her presence.

Daphne’s Catflap on Twitter

Adored Daphne, graceful empress of floof, floofybum. No adoring catflap could possibly be more blessed than me.

@raspberrypi_otd

Ben made a thing.

The Raspberry Pi OTD Twitter bot shares past posts from this very blog you are reading RIGHT NOW, and thus traces the evolution of Raspberry Pi through its tweets. One day, probably in twelve months, this very blog post will resurface on the Raspberry Pi OTD timeline, and then we shall all meet back here and say hi.

Raspberry Pi OTD on Twitter

On this day in 2015: Raspberry Pi Zero: the $5 computer https://t.co/1GRhq0TYuz

@randspberrypi

Sharing posts generated by Rand’s Raspberry Pi, this twitter bot posts random GIF-packed tweets, usually with a retro 1980s vibe and the hashtags #80s, #MusicVideo, #GIF, and #raspberrypi

Rand’s RaspberryPi on Twitter

Random #80s #MusicVideo #GIF #raspberrypi https://t.co/ieraOHGFjr

@falalala_la

Though it seems to be taking a hiatus right now, the Deck the Halls bot searches Twitter for tweets that fit perfectly to the tune of Deck the Halls, and retweets these with the classic “Falalalala, la la, la la!” as a comment. Be warned, a few of the tweets it recovers may be NSFW, but on the whole, it’s a joyful, joyful experience.

Deck the Halls on Twitter

Falalalala, la la, la la! https://t.co/r2dkE8wMFm

@bert_the_plant

I promise we haven’t killed him.

Bert is a ficus tree that lives in one of the meeting rooms here at Pi Towers. When connected to the internet, his Raspberry Pi and moisture monitor update followers about whether he needs watering, alongside a photo of his current state. And while his last tweet, dated 10 June 2017, claims he’s “so thirsty”, accompanied by a photo of pure darkness, I assure you this is simply because the light was off…and the Pi has since been unplugged…and Bert’s alive, I swear it, I swear!

Hold on, I just need to go for a walk to Meeting Room 5. No reason. *runs*

Bert Plant on Twitter

I’m so thirsty!

Connecting your Raspberry Pi to Twitter

The process of setting up a Developer Account so you can build your own Twitter bot has changed recently. But once you follow their new steps, you can still use our free resources for connecting your Raspberry Pi to Twitter.

In our Tweeting Babbage resource, you will learn how to write code that sends images from your Pi to the Twittersphere.

And if you’re a more experienced coder, you could try your hand at our Naughty and nice resource, which will walk you through creating a program that checks whether a Twitter user is in Santa’s good or bad books. After all, Christmas is just under a month away!

Santa angrily staring at a Twitter account

And from there, the world (the Twitter world at least) is your oyster.

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