Yeah, I was just contemplating how I'd do this using interrupts and found that library: http://code.google.com/p/arduino-new-ping/wiki/Ping_Event_Timer_Sketch

The other thought I had was to add an ATTiny85 to drive the range finder and then query it as needed for current numbers via I2C or equivalent, but that would make this project more complicated than I really want to deal with.

I'm working on a lighting project for Christmas gifts where I have a Nano driving a bunch of LEDs (via TLC5940's), and I want the patterns being generated on the LEDs to respond to people in the proximity via an ultrasonic range finder (such as http://www.arduino.cc/en/Tutorial/Ping, the one I'm using isn't a ping but has almost the same code to drive it).

The problem I'm having is that the code to use the range finder and read the result injects enough of a delay to interfere with the LED animations.  Do folks have any ideas on how to make the range finding be a non-blocking operation?

Does it show up in "System Information"?

Use spotlight or: Apple -> About this Mac -> More Info -> System Report

It didn't at the time.  I uninstalled the Arduino software, then reinstalled it and the FTDI drivers and it appears to work now.  Thanks for the help!

From that page:

If you're using an older board (Duemilanove, Diecimila, or any board with an FTDI driver chip that looks like this:

The Nano uses a FTDI chip.

If serial port isn't showing up, perhaps the FTDI is dead.

The problem here is that the same board shows up fine on my person MacBook Pro, but I can't get it to show up from my MacBook Air that I have at work.  So the Nano itself seems to be fine.  I'll try reinstalling everything again and see if that clears anything.

I hadn't explicitly installed the drivers (I don't think I had on my personal MacBook Pro either) and didn't think they were needed for the Nano v3 (as implied by http://arduino.cc/en/Guide/MacOSX).  However I now have installed version 2.2.18 of the drivers and the board still does not appear when connected to my MBA.  Any other ideas?

I have a Nano controlled lighting project that I'd built at home to be installed in my workplace, which I recently brought in.  While working on it at home connecting its USB cable would cause it to be quickly detected by the Arduino software on my MacBook Pro running OSX10.6 (Snow Leopard).  I'd planned to update its software from my work laptop (a MacBook Air running OSX10.7 (Lion)) but for some reason the Arduino software never recognizes the USB connection.  I've brought my personal laptop in and that still works with no issues.

Other USB devices seem to work fine (ie keyboard, mouse, ethernet adapter), so its not the USB interface itself.  Anyone have any ideas on this, or pointers to q troubleshooting guide for this sort of thing?

I recently ordered two Xbee Pros (From SparkFun, https://www.sparkfun.com/products/10421) with the plan to use them for a coordinator and a remote control device, along with a couple standard Xbee's I have which would be used for sensor nodes and routers.

The Pro's are model XBP24-B27WIT-004-revE, running firmware XBP24BSE with the most recent version.
The non-Pro's are model XB24-Z7WIT-004-revD1, running firmware XB24-ZB with the most recent version.

Using identical configuration steps I can get the Pro's to talk to each other in AT mode (using CoolTerm), and I can get the non-Pro's to talk to each other, but nothing I seem to be able to do will get the Pro's talking to the non-Pros.  Are these models just incompatible somehow?  The Sparkfun page says the Pro's aren't compatible with series 2.5 models, but I'm almost certain my non-Pro's are Series 2 which should work.

Any advice would be appreciated.

Are you going to use bi-directional communication, or just broadcast communication? Bi-directional uses more resources but lets you verify that the commands were recieved. Broadcast is simpler - just expect each device to have gotten its command - but you can continuously broadcast and if a device misses one cycle it will catch up on the next.

I intend for it to be bi-directional.  I both want acknowledgement of commands, and all nodes will also need to be able to issue commands.

Just curious - Are you using tinys instead of other logic? Program the tiny to do a function and simplify the interfaces?

I'm planning to use tiny's because I'm fairly familiar with Arduino and they can be programmed in a similar manner.  I have no doubts in my ability to code this project (ie I have 20+ years of programming experience) but my hardware skills aren't anywhere near the same level.

I would be tempted to use I2C, but I haven't used it on that chip. I2C gives you addressability, so you can send a message from one device to another one, or broadcast it.

Yeah, I was just starting to look at that, it does seem like some people have done I2C on the ATTiny85: http://www.arduino.cc/playground/Code/USIi2c

I'm not set on the particular chip, I just happen to have some and would rather make these as cheaply as possible for the functionality I need.

> Distance?

Probably a total of less than 6 inches

> Electrical or magnetic noise?

This should be negligible.

> Common power supply?

Yes

I'm planning a project that would involve a number of snap-together modules, each of which would contain an ATTiny85 and an LED driver (probably just a shift register), and later some alternate modules that do other actions.  These would all be connected to each other, with the idea that commands are relayed between the modules.

My plan is to use the Arduino software and use the Arduino as an ISP through that and have verified that I can program the ATTiny's without problem.

My current question is how best to do the communication between the attiny's.  Is there a good existing method of doing this (or a open-source project that does something similar)?  I'm pretty sure I could write custom interconnect code (I'm a professional software engineer, I've written network protocols before) but figure there's something already out there.  What would you folks recommend?

Oh - and let's not forget playa dust - stuff as fine or better than cake flour; it gets everywhere and inside of everything no matter how hard you try to seal things. Once you go to the playa, you carry a bit of with you everywhere forever (probably a good amount in your lungs, given the whiteouts I've seen and experienced).

I'm actually quite aware of the difficulties of the dust, this is going to be my 10th year so I decided its time to work on a pretty big project.  All the electronics are going to be in a sealed box, probably laser-cut wood for the control box (possibly metal from Techshop's water cutter, really haven't determined what aesthetic to go with), and the project is night-only so its cooling needs will be limited.

Unfortunately, OP, I can't tell you anything about RF interference or other issues; make sure your communications protocol is fairly fault-tolerant and has a failsafe state in the event of a garbled transmission...

Thats a good point.  I'm actually a software engineer specializing in distributed systems in my day-to-day life, so I hadn't really been concerned with the easy things yet.  I'm just trying to determine what hardware to use first so I can get that together to get a prototype set up.

You don't know how much data you will be sending between the controller and the Arduino? You don't know how often?

Or you do, but won't say?

I'm confused.

Sorry, thought you were re-asking the question about interference.  This application is going to be a fairly low and intermittent data volume as it'll mainly be transmitting data from a joystick plus a number of buttons (along the lines of a game controller, controlling some stepper motors and some relays).  With the heaviest use scenario I couldn't imagine this going past 1kB/s, probably more on the order of 100B/s.

So, how much data, how often?

I really can't say, thus the asking here to see if anyone has experience with it.  There's less of the standard urban interference, ie almost no cordless phones, bluetooth, wifi, etc.  However there are a lot of random other projects to create interference, tons of generators, lots of walkie-talkies on various bands.

I'm currently investigating putting together a remote control console for a project I'm involved with building for Burning Man. The console and the project itself are going to be arduino controlled and my first desire would be to use XBee modules to communicate between the console and the project controller, as the console needs to be roughly 100ft from the project itself and would preferably be mobile. A team member had expressed concerns that there may be a lot of interference from random other sources on the playa, does anyone have experience using these wireless modules in the desert?