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Arduino programming: Advanced Servos

For a while now I wanted to share what I learned in programming Arduino and AVR micro-controllers in general.  Most of the topics I want to discuss are above basics.  There are already plenty of basic tutorials online, so no need to reinvent bicycle.

However don’t be discouraged by “advanced” title. I will attempt to explain it in terms even a very beginner programmer can understand.

Let’s start with servos. I only started to play with servos about a month ago, and found how fun controlling them can be. But also challenging.

I won’t go into details about servo types, specs, uses, etc. but I do want to mention a few things about ways to control them.

There are essentially 3 ways to have full control of a servo.

You can do it directly with Arduino or similar AVR microprocessor using PWM pins or a Servo library that allows you to use even non-PWM pins.
An external PWM expansion board like Adafruit’s 16 channel servo controller
A dedicated “smart” 32 channel servo controller board (i.e. RTRobot)

In this topic I will talk about first option, however let me talk just a little bit about options 2 and 3.

An external PWM controller is just an extension of Arduino’s own PWM ports.  These are usually controlled via I2C bus and can be chained together to control a huge number of servos.  These are great but a little more difficult to control and will rely on your micro-controller’s CPU.

A dedicated servo controller board usually have it’s own microprocessor (ARM), in many cases more powerful than Arduino.  These are fantastic boards, that can store servo movement macros that can be initiated by Arduino serial commands. If you are building a robot like hexapod, you can pretty much program movement sequences into controller’s memory and offload your Arduino to do other tasks.  Some even come with PS2 wireless controller capabilities!

But if you only have a handful of servos to control, doing it directly from AVR is probably the best choice.

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December 19th, 2016|

New product: EDC Spinner Fidget Toy

Do you ever find yourself fidgeting with some random object on your desk?  Rolling a coin or a pencil? Clicking pen?  Shuffling post-it notes?  I personally spin and glide my iPhone on the desk (“air hokey” style) when I’m in a particular boring meeting at work…

Believe it or not there were some studies done that showed benefits of “fidgeting” such as better concentration on tasks and even some physical health benefits!

Well new craze is in town and it’s called EDC (Every Day Carry) Spinners.  They are low tech devices that have a skate bearing (usually 608 type) in the middle and several more on the outer edges.  Those outer bearings are just for weight and looks and I’ve seen others use metal balls or other weights instead.  Some of these fidget toys have 3 arms (4 bearings), some have two and some have more.  They are most commonly 3D printed, but some are milled from metal and wood.

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November 4th, 2016|

Flip-dot displays at Maker Faire

Thanks everyone who showed interest in my Flip-Dot display exhibit (Flipster Clock) at 2016 NY Maker Faire!

I know I haven’t written anything about how I got these working yet.  It was simply because I haven’t […]

October 5th, 2016|

DIY Pin table V2.5

A while back I wrote about making pin “vector” table for laser cutter (here and here).

There were some issues with it that I discovered later on.

First issue with rivets height.  I don’t know how I […]

May 3rd, 2016|