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1  Using Arduino / Project Guidance / Re: Controlling an array of 64 small motors on: June 21, 2012, 09:18:49 pm
Hmm. And I think I just found half the answer to one of my problems.  Here's a guide to controlling the exact same stepper motor controller board that I found on eBay, using Arduino:

Is anyone familiar with the Arduino program the author references ("stepper_oneRevolution") and know whether it could be run on the ATtiny85 rather than Arduino?  If so, that sounds like a possible solution to me: Each of the 64 ATtiny85s is connected to a ULN2003 driver board and runs a modified version of the "stepper_oneRevolution" program.  Each ATtiny85 is programmed with its own unique 6-bit address number (0-63), and listens for 2-byte instructions over a common serial interface from the central Arduino.  The first byte of info is the address, the following byte is a command to turn x number of revolutions in y direction, which the selected ATtiny85 translates into instructions for the ULN2003 board using the "stepper_oneRevolution" code.

I'm thinking out loud, ja?
Anyway.  Sound reasonable?

2  Using Arduino / Project Guidance / Re: Controlling an array of 64 small motors on: June 21, 2012, 08:47:14 pm
Wow. Thanks all - That's all just a little over my head at the moment, but I think I'll get there soon.

A bit more info about the project would maybe help. You say to raise/lower 64 objects of about 5KG weight by about 25mm but will the movement be either fully up/down or can it be any position between. Also how fast must it raise/lower.

Sorry Riva - I was a bit vague!  Yes, I need to raise/lower the objects by a discrete (measured) distance rather than just all the way up or down, although the speed of movement is quite inconsequential - I'm moving a series of lights and mirrors and other objects in response to infrequent changes in the environment.  Nothing needs to happen particularly quickly.  Accuracy is the most important thing.

I had a read of that arduino playground article and some other info about the ATtiny85 - sounds promising to me (although at the moment I have no idea what communication protocol that motor controller I linked to uses - can anyone point me in the direction of something useful??).

The other thing that came to mind, rather than using ATtiny85s, was having some kind of ICs that could be allocated an address number using a series of DIP switches or hard-wiring, and which only allowed messages corresponding to their hard-programmed address number to pass through to the motor controller.  Does such a thing exist?  If so, can anyone let me know what it might be called?

Thanks for the ideas! This is starting to look a little less impossible....
3  Using Arduino / Project Guidance / Re: Controlling an array of 64 small motors on: June 21, 2012, 04:07:58 am
Thanks MikMo...

So, I've figured that what I probably need are stepper motors, each with its own controller so I don't have to send insane amounts of control information directly to the motors.

Has anyone ever used something like this motor + controller combo?:

I'm guessing that this unit receives some kind of instructions from an Arduino over a 3 or 4-wire interface, such as "spin left for x turns"...??

Assuming it's powerful enough for my needs (I'll probably end up using some kind of gearing), does anyone know of a simple chip that could interface with the motor controllers in a way that MikMo described?   Suppose my central Arduino sent out two bytes of info at a time: the first to select which motor to control, the second to give the motor controller an instruction like "spin right x turns" - all this chip has to do is listen for its unique ID in the first byte, then route the following byte of info through to its respective motor controller.

4  Using Arduino / Project Guidance / Controlling an array of 64 small motors on: June 21, 2012, 01:22:40 am
Hi all...

I've been commissioned to do an installation which requires many small moving parts. I need to individually raise or lower 64 objects, each weighing up to 5kg, by about 1 inch in either direction.  This will be achieved by a rotating threaded rod/bolt assembly below each object.

It will be easy to make the raising/lowering mechanisms manually adjustable.  However, since there are so many of them, each requiring frequent and accurate adjustment, it will be tedious to make the adjustments by hand.  Why not automate it somehow?

So... Could anyone suggest ways to tackle this problem?  My first thought is a series of 64 motors which can be told to spin a certain amount in either direction, turning the threaded rods and thus raising/lowering the objects by an exact distance.  To minimise wiring (highly desirable) each motor would have a controller circuit with an ID number and would "listen" for commands sent to it from a central controller (arduino).  I could tell motor number 27 to spin 8.5 turns clockwise, or tell all motors to spin 30 turns anti-clockwise.  Hopefully just using a 2-wire interface.  That kind of thing.  It sounds ridiculously complicated to me, but from past experience with arduino I've learned never to say never... smiley

How does that idea sound?  And could anyone point me in the direction of components to start researching?  I don't even know the names of the things I'm talking about... or if they even exist...

Other suggestions??

5  Using Arduino / Motors, Mechanics, and Power / Re: off-the-shelf automated 240v power switches: arduino compatible...?? on: June 30, 2011, 12:04:20 am
@mem - thanks for the link! i'm looking into that now - certainly seems promising...  it might just be a matter of using a plug adapter for australia as the UK voltage is generally compatible (230v vs 240v...). 
has anyone experienced 230v power boards triggering safety cutouts when they get fed 240v??  seems like an insignificant over-supply to me...

@markbee: yeah, thanks - i saw that product too... so tempting, but unfortunately i can't use it for my application. as soon as i do any 240v wiring, i void the insurance smiley-sad one downside of working with public institutions... sigh.
6  Using Arduino / Motors, Mechanics, and Power / Re: off-the-shelf automated 240v power switches: arduino compatible...?? on: June 29, 2011, 10:09:56 pm

awesome! thanks markbee- that's exactly the kind of thing i need...

only problem now - does anyone know of a similar unit that can work on australian 240v?
7  Using Arduino / Motors, Mechanics, and Power / off-the-shelf automated 240v power switches: arduino compatible...?? on: June 28, 2011, 09:42:20 pm
hi all,

i'm controlling an arduino (amongst other things) from a puredata patch with the aim of making a programmable climate control system.

i need to turn on and off various 240v/10A heating or cooling devices automatically.  BUT i'm not a qualified electrician and as this project is taking place at a public institution, i can't construct the 240v side of the system myself as this would void the building/liability insurance.

so i'm looking for a cost-effective off-the-shelf solution that can somehow interface with either arduino or the computer i'm running the puredata patch on - which happens to be an OLPC XO laptop running xo-ubuntu intrepid 8.10.

my ideas so far are:
1. some kind of midi-controlled power board similar to what theatre lighting techies use.  i know nothing about these, and they sound expensive to me.  but i can easily send midi messages from arduino.

2. some kind of X10 or IP-enabled home automation switches.  maybe i could bypass arduino altogether and somehow have puredata communicate with a home automation switch over a wifi network...?

3. a commercially manufactured power switch designed to interface with a microcontroller using a relay.  i've tried looking for these, but not knowing what they would be called, i've had no luck yet.  this would be the ideal solution i guess - simple, and sounds cheap.

any ideas??

8  Using Arduino / General Electronics / Re: how fast is a bluetooth keyboard?? on: April 08, 2011, 02:25:00 am
great... thanks for the ideas guys.

the link for the BT dongle external antenna (thanks bigphish) is slightly corrupt - correct address is:
i'm using my laptop's internal BT receiver so not sure i can do that - but actually i think 5-7 meters is an absolute maximum distance for me - normally it should be round 1-2meters...

think i'll have a go hacking a BT keyboard and hopefully post findings here...
9  Using Arduino / General Electronics / how fast is a bluetooth keyboard?? on: April 04, 2011, 03:14:09 am
so, i figured a few people here may have experience using wireless bluetooth keyboards, and was wondering if anyone knows what a typical response time would be for keystroke data to be received by the OS.

why do i ask?  i'm working on a musical instrument design that involves a wireless pedal/button interface.  i need a solution that is very cheap and suitable for use in a stage environment at a distance of about 5-7 meters.  i also need one that has a fast response time to minimise "latency".  ideally i would like keystroke data to have a maximum 1ms transmission time.

is this possible with a bluetooth interface?  i seems quite easy to find relatively cheap wireless BT keyboards these days, so i thought i'd give it a go.


10  Using Arduino / General Electronics / Re: cheap and simple audio delay schematic? on: March 10, 2011, 08:28:20 am
precisely the kind of chaotic side-effects i'd like to explore with this instrument, jack.  what's wrong with the odd bit of end-stop bashing and self-destruction, eh? ;)
11  Using Arduino / General Electronics / Re: cheap and simple audio delay schematic? on: March 10, 2011, 01:49:38 am
oh, i forgot to mention that yes - i have considered just putting some pickups under the metal bars, then running the signal through an amp placed somewhere next to the instrument.

the idea here is to make an instrument that feels just like a traditional, pipe-resonated vibraphone when you play it.  to achieve this, there needs to be a direct interaction between the reproduced sound and the physical vibration of the metal bars.  kind of like a feedback effect.
12  Using Arduino / General Electronics / cheap and simple audio delay schematic? on: March 10, 2011, 01:11:37 am
hi all -

just wondering if anyone could help me out with the non-arduino side of a musical instrument design problem.

i'm designing an electro-acoustic vibraphone.  instead of using air columns (resonator pipes) to amplify the metal bars, i want to use audio speakers.

the problem:
in order to resonate (and thus amplify the fundamental note of the vibrating metal bar) the sound waves traveling from the speaker need to arrive at the metal bar at precisely the right moment to complement its movement.  if the sound waves from the speaker are out of sync with the vibrating bar, they might "cancel-out" the movement of the bar, therefore making the note sound "dead".

i can solve this problem in one of two ways.  one way is to change the distance between the speaker and the bar, so that the sound waves arrive at the bar at precisely the right moment.  i can't do this since i'm using one speaker between several notes, and i want to make the instrument compact.
second method:  use some kind of audio delay, like this:

this is how i'd like the delay modules to work:

this way, i can "tune" the electronic resonator by adjusting the delay time so that the sound pressure levels from the speaker coincide with the bars' vibrations.

further problems:
1. i don't know how to make a delay circuit like this, and
2. i need many such delay modules, one for each note of the vibraphone, so they need to be cheap and easy to make.

is anyone able to suggest a suitable schematic, or point me in the right direction??


13  Forum 2005-2010 (read only) / Syntax & Programs / Re: multitasking with arduino on: February 19, 2007, 02:21:54 am
the 'samples' i want to export are just 12-odd-bit numerical data, representing either musical pitches or other control information (sorry about my lack of technical vocab...).  if serial is fast enough, i'll use that just because it's easy.  otherwise i'll use as many spare digital pins as possible to improvise some kind of parallel interface.

i need to provide a relatively smooth, rapid stream of data, as compared to the data i get from the sensor, which is slow(ish) and sounds jittery when i feed it to a tone generator.  the data could also be sent to some kind of DAC for conversion to control voltages, or perhaps routed over a midi interface, or sent to any number of different gadgets.

so ideally, i'd like to have some kind of program structure that splits arduino's processing time between the tasks of communicating with the sensor, and sending out a smoothed data stream.

another option is perhaps some kind of external processor that takes the data direct from the sensor, or arduino, and does the smoothing automatically... but i've never heard of such a thing, or know what it might be called...

any ideas?
14  Forum 2005-2010 (read only) / Syntax & Programs / multitasking with arduino on: February 18, 2007, 07:56:20 pm
is there an easy way to program arduino to carry out 2 tasks simultaneously?

for example:
i'm developing code to interface with a sensor over a SPI interface.  data readings from the sensor are clocked into arduino at about 500 times per second.
i want to smooth the data using some routine similar to the [LINE] object in max, so that i can output a stream of data from arduino at a higher rate (about 6000 samples/sec) to another device.
just wondering if there's a way to run the data smoothing routine AND the sensor acquisition routine simultaneously, without having to intersperse bits of code...?
15  Forum 2005-2010 (read only) / Syntax & Programs / Re: some syntax not in arduino refernce guide? on: January 23, 2007, 12:58:08 am
wow.  thanks so much you guys.  i think i totally understand now! and that bitmath page is AMAAAAZING!  really useful.

as a total newcomer, i think i agree with mellis - having absolutely everything compiled into the reference guide may look daunting initaially, but in the long run it saves a lot of confusion.  the processing reference is a good example of how newcomers can be introduced to the more basic concepts first, then have the opportunity of expanding on what they've learned.  i've also been teaching myself max/msp, which at first seems hideously complicated, but if you work through the pdf tutorials in the documentation it's perfectly understandable, since the examples are so well explained - and if you ever want to find out about something a lot more advanced, the info is always easy to find.


just one more question - can you put chunks of C++ code into an arduino program?  is there any difference between the two? i've never seen C++ code, so i'm a bit confused as to why everyone is talking about C++ when i'm trying to learn arduino...
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