Recent blog entries for shimniok

Teaching Programming to Kids (Cont'd)

After much struggle to select a microcontroller and programming system for teaching programming to my 5th grade club, everything suddenly came together.

In a flash I remembered PICAXE, which are low cost BASIC-programmable microcontrollers.

Even better, since all the kids have Chromebooks, PICAXE can be programmed with a Chrome App using the Google Blockly graphical programming framework.

For example, an LED blinky program looks like this:


As pointed out by my SHARC pals during a lunch discussion, 5th graders aren't expert typers so this kind of graphical block system sidesteps a lot of frustration. And I feel this system is better suited for robotics than native Scratch is.

The PICAXE Blockly IDE has some neat features.


First, the IDE includes a simulator so kids can run their code safely before trying it on the robots.

Second, they can see the BASIC language program by clicking a tab so they can get an introduction to standard programming languages.


My sample PICAXE-14M2 is now successfully blinking an LED on pin B.5. Soon I'll be prototyping motor control using the Pololu DRV8835 driver breakout boards I bought during the Black Friday sale.

And, I'm almost done designing a baseboard, similar to my PIPduino, that uses a Pololu step-up/step-down regulator (S10V4F5) for power, also a Black Friday purchase.


Since the PICAXE programmer cables are too costly for our budget I'm going to find or make cheap FTDI breakout boards or else put an FTDI and USB connector onboard.

It feels good to have finalized the MCU and programming system for the kids' robots. I'll order the baseboards soon and hopefully I won't have screwed up anything so we can get started programming in 2-3 weeks.

Syndicated 2016-11-29 01:00:00 from Michael Shimniok

24 Nov 2016 (updated 25 Nov 2016 at 17:07 UTC) »

Black Friday / Cyber Monday

Here's a list of sales you'll want to check out this Holiday:

Pololu Black Friday - already started! And an awesome sale with great deals once again. My order is placed :) Switching power supplies, robots (Zumo, 3pi, and the new Romi chassi); IR rangers from Sharp, Polou, and a time-of-flight breakout; wheels, motors, motor controllers, the cool A* ATmega32U4 controllers, and lots, lots more. Plus freebies and free(ish) shipping.

Sparkfun Black Friday / Cyber Monday - a wide range of items on sale this year. I'm eyeing the ESP8266 boards, MicroView, as well as the HackRF and RockBLOCK Iridium SatComm module. The FLiR Lepton board is on sale too.

BGMicro has a sale going right now, too. Take 10% off your ENTIRE order by using the code TTM at checkout through 11/23.


Parallax has a sale going too. Save $30 or more on:
Trossen robotics: 
We're taking 20% off RobotGeek and Interbotix products! Use coupon code "Friday16" at checkout.

Newark has tons of overstock stuff for sale


Syndicated 2016-11-24 04:02:00 (Updated 2016-11-25 16:35:20) from Michael Shimniok

On Teaching 5th Grade Programming

I know that 5th graders can code. 


The kids last year did a great job programming their Lego Mindstorm NXT robots in LabView, although I witnessed some confusion about the graphical representations. Perhaps Scratch, specifically Scratch 4 Arduino (S4A), might be an option. MiniBloq would be another possibility.

Still, I feel it will be easier for kids to learn a syntactically simple text-based language, like Python, Lua, BASIC, or SPIN. Why not C-syntax languages? I have witnessed too much time wasted on syntax problems--semicolons and braces--which I think distracts from core learning.

It is a bit of a quandary for me. What do you think?

Microcontroller Board

Low cost is a key factor. We'll have 5-7 teams, so anything that costs $25 or less would be affordable.

With DIP microcontrollers, we could use breadboards (adding slightly to cost) but kids may spend more time troubleshooting loose wires than solving the problem so I'd prefer to build a baseboard.

I am a huge fan of 3-pin servo-style connectors for my robots which greatly simplifies wiring, but non-reversable connectors would be better.

There's always the Raspberry Pi Zero at only $5. The cost is right but the kids may have to learn some basic Linux and we'd need a baseboard with serial or bluetooth. And honestly a Pi is way overpowered for what I have in mind.

Python

Since learning Python, it feels like the BASIC of the new century. It's way more powerful, but simple to learn the basics, is wildly cross-platform portable, hugely popular, and much more. 

And of course I'm a big fan of MicroPython, which powers OpenMV Cam.

However, it is quite a challenge to find an suitable microcontroller board with a full MicroPython port that doesn't cost too much. PyBoard is over budget and requires a baseboard too. Teensy 3.5 and is powerful and low cost, but requires a baseboard and the port isn't done yet. 

Lua

Seems good for education and the interpreter is somewhat lightweight like MicroPython but, similarly, choices of microcontroller boards appear to be limited. And Lua is nowhere near as popular as Python so they might struggle more to find help after the club.

BASIC

This old language lends itself well to education. It's about as lightweight as interpreters come, so I should be able to get a BASIC implementation running on my PIPduino, which would be free for the club (thanks to glacially slow sales).

Coridium's $10 ARM-based BASIC Chip, which is an LPC1114, is designed for embedded use and even the cost of fabbing a baseboard wouldn't kill the budget.

But BASIC isn't standardized across platforms so I'm not sure they could readily apply what they've learned on their PCs like they could with Python or even Lua.

Syndicated 2016-11-08 13:00:00 (Updated 2016-11-08 13:00:27) from Michael Shimniok

Teaching 5th Grade Electronics

I'm pleased to say that I'm shaping young minds into engineers, leading an after-school club called Technology - Robotics - Innovation at my daughter's elementary school.

Week 3 is coming up this Thursday.

Week 1 was introductory and included a fun bridge-building team exercise where we got to flex our teamwork and problem-solving muscles. 

Week 2 the kids had fun learned about electronics: voltage, current, LEDs and built their own LED circuit on breadboards. 

Great news: half the kids build non-working circuits. Exactly what I'd hoped for! See, I didn't tell them that LEDs conduct current in one direction so that they could learn through thinking and discovery. 

Students came up with great ideas on what might be wrong and some discovered that flipping the battery connections lit the LED (nice!). When I told them about LEDs and diodes, they fixed their circuits by flipping the LEDs.

We'll build on the LED circuit and their light-sensing soldering kit circuit to develop sensors for line following. After Thanksgiving, they'll build team robots. Then we'll start on programming!

I plan to publish the curriculum and materials as open source / creative commons for others to use and help us improve it.

This is a dream come true. I've been wanting to teach these things for several years now and I'm super excited to finally have that opportunity!

Syndicated 2016-11-07 19:00:00 (Updated 2016-11-07 19:00:08) from Michael Shimniok

Robot Sumo with Lego Mindstorms

Two deadly, plastic opponents face off.

Their beeps and whirs are drowned out by the deafening cheer echoing in the elementary school auditorium.

Two robots enter the sumo ring. Only one emerges, victorious. The other? Tipped over, out of the ring, parts scattered, wheels spinning in futility...


The culmination of many weeks of tinkering, teams from the Robot Club at my girl's elementary school faced off against teams from two other schools in a Lego Mindstorms Sumo death match (ok, they didn't call it a death match... but I sure will).


For several weeks I came in every week to help the kids design, build, and code their robots and it was incredibly fun and rewarding. Turns out 5th graders are really smart. The kids had no trouble with the LabView-style graphical programming and had working robots quickly.


There were a few physical design issues. Teachable moments in the area of physics were plentiful. Center of gravity. How caster wheels work. Traction, friction. Stuff like that. In the end our school fielded some very competitive robots!


One team started a few weeks behind but was able to build a tracked robot (below) based on some instructions I dug up. They fought against time for weeks and finally, in true robot experimenter fashion, got their code working only days before the competition.


I built one, also. And battled the kids. And lost more matches than I won!

I guess I am not smarter than a 5th grader.

But I definitely couldn't be more proud of these kids for sticking to it, never forgetting to have fun, and building some awesome sumo bots.

Syndicated 2016-05-23 23:30:00 (Updated 2016-05-23 23:30:07) from Michael Shimniok

2 Mar 2016 (updated 2 Mar 2016 at 18:07 UTC) »

Sparkfun AVC 2016


Sparkfun announced that the 2016 Autonomous Vehicle Competition will be happening in September this year!

That's good. It'll be cooler than summer, almost certainly sunny and a pleasant 70-80 degrees. Plus we have loads of extra time to procrastinate. Win-win!

The big news is they're making some kind of addition to the AVC involving -- if the pictorial hint is to be believed -- little kids driving around in home made go-karts?!? Or... I really don't know...

What does it mean!?!?!?
Maybe autonomous road racing? That'd be sweet. Maybe kids will race with bots? Maybe robot kids will... nevermind.

What about me? Though life has been leaving boot prints on my backside for the better part of the last year, IF the AVC additions are super-interesting, Data Bus may have to make a comeback.

I haven't forgotten about rovers. In fact, I've been working on some Rover-related goodies in the meanwhile...


RoverPower [github] is ready for field testing. I wanted to eliminate the quirks of Data Bus' old switched regulator and this new design should do so with extreme prejudice.

It provides rovers with 5V, 1A from an automotive-grade LM2940 5V 1A regulator  [datasheet.pdf] with 6-26V input and low dropout voltage. The current design supports up to 3S battery.

With over-voltage, over-current, over-temperature and reverse polarity protection, not to mention the ability to effortlessly shrug off massive voltage spikes from inductive loads, the LM2940 will survive the worst a Rover can throw at it without breaking a sweat.

And speaking of which, the board's efficient thermal dissipation design mean you get to use all 1A out of the regulator without thermal overload. Filtering capacitors ensure plenty of clean, stable power for sensitive rover electronics.

During initial tests, an earlier version of this design solved spurious resets due to motor voltage spikes on my RedBot (Magician) robot. We saw these symptoms on robots entering the Parker Rover Rally and Data Bus' old regulator would shut down at odd times. This board should solve all of these issues.

RoverPower sits between Battery and ESC with 4 pairs of 5V/GND pins for clean, simple wiring.

This configuration also sets the stage for an I2C-based voltage/current sensor, RoverMeter [github], based on the INA138 (or INA168) sensor IC that monitors voltage drop across a shunt resistor.

Where it's different from the rest of the pack is the addition of an ATtiny onboard that will provide signal processing and an I2C interface so you get stable, accurate measurements.


Good ol' RoverMux is still available on Tindie and in its current revision, is as easy as can be to hook up, while remaining dead reliable. It's been saving Data Bus' bacon since 2011.

My RoverGyro will need a redesign. The chip it was based on was prematurely declared EOL. What to pick instead? A few folks on the DIY Rovers list have been raving about the Bosch BNO055 [datasheet.pdf] which is actually a 9DOF IMU system-on-chip featuring a built-in ARM Cortex M0 performing sophisticated sensor fusion.

I've been tinkering with a few other Rover boards too. Now that the AVC is announced, I guess I better get busy and get these designs finished, tested, and available to buy on Tindie. :)

Hopefully, too, OpenMV Cam rewards will ship in a few months and go on sale, so folks wanting to employ machine vision will be able to do so.

Syndicated 2016-03-02 00:00:00 (Updated 2016-03-02 17:45:55) from Michael Shimniok

Chinese Robot Kit

Kids can build robots, sure, but... which robot kit should be their first?

Lego Mindstorms? Pololu 3pi or Zumo? What would you recommend?

Every time I show my robots to elementary school kids that are really interested in building their own, I realize that I can't recommend a good starter robot kit. Why not?

I feel prospective roboteers deserve a kit that is low cost, can do two or more interesting things, is expandable, and is accompanied both by quality learning material and programming software that younger kids can understand and use.

So, I want to roll my own kit. But, where to start? Maybe... here:


I searched for a low-cost chassis and found vendors on AliExpress selling a robot kit.

It includes an Arduino clone, sensor shield, battery holder, motor driver / regulator board, motors, encoder discs, wheels, caster, and an acrylic chassis.

All for a ridiculously low price. Was it any good? Read on...

Kit Review

What you actually get in the kit is a good start, but you'd need some additional bits to make it all work.

The motors come with wires, mounting brackets and hardware, and encoder discs, but no encoder boards. The chassis and hardware are very similar to the Sparkfun's now-retired
Magician robot chassis.

Pan-Tilt bracket
There's a pan-tilt head similar to the one sold by Adafruit, but the kit includes only one of the required two 90g micro servos. Fortunately I had an extra laying around. The bracket is supposed to clip into some unknown FPV camera, I think.

The power board includes an H-bridge motor driver IC (L298N) with robust heat sink, and a 7805 linear 5V regulator.

However, for all the boards, you must supply the standoffs and mounting hardware and you get to drill your own holes, unlike the Magician. A sonar sensor is included, though with no mounting bracket.

Still, it's a good starting point. Even after you add the missing pieces, total cost should be far south of $100.

You can always add on Sharp IR distance sensors, line following sensors, a robot firefighting apparatus, a claw, or various other things.

Bot Thoughts Electronics?

PIPduino has I2C, SPI,  servo headers.
For my kit, I think I'd rather use in-house, Bot Thoughts electronics. My Uno-compatible PIPduino lends itself nicely to robotics, for example.

My RoverPower regulator board is a good fit, too. I'd need to design a motor driver board, though.

Or, perhaps source a nice switching supply and motor driver from Pololu instead.

The basic kit would have to include encoder sensors and some multi-purpose environment sensing. Expansion kits could be added for specific purposes like maze solving, firefighting, sumo, and line following.

Programming

For programming, I know the Lego Mindstorms visual programming language seems to work, because the robot club at my daughter's elementary school use it with success.

EV3 Visual Programming
Scratch for Arduino might be an option; it's for ages 6 and up and is popular, apparently. Or, Minibloq, the first Kickstarter I backed, developed by folks who regularly teach robotics to kids.

For older kids I'm thinking MicroPython would be ideal. Or ... (looks around nervously) ... BASIC, which is what I learned on. The Coridium ARM BASIC chip is an option.

There is something to be said for simple syntax, no semicolons, and no curly-braces...

Well, what do you think? Worth doing? What would your kit look like? Let me know in the comments or click the "Contact Me" link on my blog page.

Syndicated 2016-02-24 00:00:00 (Updated 2016-02-24 00:00:09) from Michael Shimniok

30 Nov 2015 (updated 30 Nov 2015 at 18:12 UTC) »

Cyber Monday 2015

Updated with lots more sales going on!

Tindie.com

Bot Thoughts

20% off - 80CFB16
10% off - 6B54471

HackARobot

  • Hackabot Nano, Arduino Robotic Kit, $30 off (coupon code : 8882BB8)

PartFusion

  • 10% off all products with F3E57A2 from Black Friday to Cyber Monday

FemtoCow

30% off of selected products with 849EA4C

Bobricius

And my flagship, new 2016 model

limpkin

f0086

nick64

Pololu

Happy Thanksgiving from Pololu! Our Black Friday/Cyber Monday sale is almost here! We will be offering huge discounts on hundreds of products and automatically upgrading you to the next best price break for everything else. We will also have some great limited-quantity doorbusters. The special offers become active Wednesday morning (November 25) at midnight PST (3:00 AM EST/08:00 UTC), and the sale runs through Cyber Monday (November 30), ending at 11:59 PM PST. More information is coming soon, including a full list of the doorbusters and sale items, but for now, here is a sampling of the discounts.

Sparkfun

Cyber Monday and all its glory is nearly upon us! For this year's celebration of festively-timed discounts, we're putting a huge selection of some of this year's best-selling and most popular products on sale for one day only – from 10-40% off! Check out our Cyber Monday page to get the scoop on the day's special deals!

GHI Electronics

Let's get right to our Black Friday through Cyber Monday Sale.
  • $1 Holey board
  • $3 Holey Moley board (limited edition, only available during this sale)
  • $8.88 mBuino mbed
  • 50% OFF
    • Cerberus boards (Cerb40, Cerbuino, Cerberus)
    • G120HDR
    • G30HDR
    • FEZ Spider Mainboard
  • 20% OFF
    • FEZ Reaper Tinker Kit
    • all NETMF Development Systems
    • all Raspberry PI HATs
    • BrainPad .NET
The sale is available for 4 days but the stock may not, so place your order now!
https://www.ghielectronics.com/catalog/sale

Electronics Goldmine

$5 flat rate shipping, lots of things on sale--too many to list.

Check them out here: www.goldmine-elec.com

Ham Radio Outlet

Lots of rigs on sale, check them here: hamradio.com

A Main Hobbies

Electronic kits 10% off, 15% off all else.

Particle

Today Only: Particle Sale

30% Off Your Favorite Particle Products

 
Ah Cyber Monday—the nerdy younger sibling of Black Friday. It’s one of our favorite shopping holidays here at Particle, and we couldn’t help but to get in on the fun. For today only we're offering 30% off some of our favorite Particle products like the Internet Button and Photon Kit. The ideal gifts to get for the engineer in your life, your favorite colleague, or, let's be honest...yourself.
 
 

Syndicated 2015-11-30 14:23:00 (Updated 2015-11-30 17:18:20) from Michael Shimniok

25 Nov 2015 (updated 25 Nov 2015 at 17:11 UTC) »

Cyber Monday, 2015

Bot Thoughts

20% off - 80CFB16


10% off - 6B54471

Coupons good per sale for any one item from Monday, Nov 30 thru Friday, Dec 6, 2015.

Pololu

Happy Thanksgiving from Pololu! Our Black Friday/Cyber Monday sale is almost here! We will be offering huge discounts on hundreds of products and automatically upgrading you to the next best price break for everything else. We will also have some great limited-quantity doorbusters. The special offers become active Wednesday morning (November 25) at midnight PST (3:00 AM EST/08:00 UTC), and the sale runs through Cyber Monday (November 30), ending at 11:59 PM PST. More information is coming soon, including a full list of the doorbusters and sale items, but for now, here is a sampling of the discounts.

Sparkfun

Cyber Monday and all its glory is nearly upon us! For this year's celebration of festively-timed discounts, we're putting a huge selection of some of this year's best-selling and most popular products on sale for one day only – from 10-40% off! Check out our Cyber Monday page to get the scoop on the day's special deals!

Syndicated 2015-11-25 13:00:00 (Updated 2015-11-25 16:50:01) from Michael Shimniok

Fixing Flaky LCD Monitor with ESR Meter




My Dell E2210H LCD monitor was really wonky.

Powering up from sleep, it would only occasionally come back to life, usually after resetting itself several times.

More often, it would power off or go into power saving mode, leaving the front panel buttons inoperative.

Occasionally it would reset or power off while operating normally.

Here's how I fixed it, using my DIY ESR test harness to find a bad capacitor without desoldering.

You can find disassembly videos and tutorials out on the web specific to your monitor. Remember, safety is your responsibility so please learn how to safely deal with dangerous high voltages, how to safely discharge capacitors, etc.

Low voltage drop; low ESR.
Meanwhile, after disassembling, I used my
Equivalent Series Resistance (ESR) Test Harness to identify bad aluminum electrolytic power supply capacitors.

The device sends a 1.0 Vp-p, 1kHz - 250kHz square wave through a capacitor on the board while the oscilloscope displays voltage drop across the capacitor.

You turn on the ESR harness, connect Channel 1 to the Probe BNC and Channel 2 to the Trigger BNC.

Then touch the red/black probes to the positive/negative capacitor terminals while they are on the board. Which is nice; you don't have to desolder every cap.

High voltage drop; high ESR.
The harness incorporates a voltage divider, so you can compute ESR based on voltage drop and the harness' series resistance.

But usually it's really obvious when you find a bad capacitor.

What you should see is a very low voltage drop across the capacitor as pictured above right.

A capacitor with overly high ESR will drop far less voltage as shown below right.

And that is just what I found on one of the 100uF supply capacitors on the main driver board for the LCD. The rest of the capacitors tested ok.

The bad cap looked fine but tested bad.
The test harness I built uses a 6.8 ohm series resistor so the ESR is computed as:


Normal ESR for good capacitors of similar size are orders of magnitude less than that.

With such a high ESR, the capacitor was slowly charging and discharging, likely confusing whatever circuit or MCU was controlling the main power.

After replacing the capacitor with a good one, the monitor works normally, as expected. All with a minimum of work and the very low cost of a capacitor.

Admittedly, I somehow missed the bad capacitor the first time I tested so I ended up buying a power supply board. Now I have a spare. Oops.

Syndicated 2015-09-22 00:00:00 (Updated 2015-09-22 00:00:07) from Michael Shimniok

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