arduino

[Tandum (Robin)]

I bought a Honeywell compass chip on a breakout board with a view to using it to get accurate positioning on my dome. This chip talks on an I2c bus an I had a USB-> I2c device I'd never used. I downloaded the free Visual Studio 2012 express as all my IDE's are really old, I haven't done any real programming in over a decade.

I had a go talking to it with VB and it sort of worked but vb is not familiar to me at all, so I moved it all to C# and everything snapped into place. I got it returning headings to me on the PC via a USB cable and I got it sending az updates to poth. Magic.

Next step is to remove the usb cable. I have a bluetooth modem which will connect my pc to a ttl serial connection at the other end. To convert that serial to I2c I could use a programmed PIC chip, which takes a lot of effort, or use one of the ardunio boards. I have both coming to see.

Surprisingly I'd never heard of the ardunio boards before this. So I ordered an UNO board from an ozzie shop and then checked out the software. They have made it very C'ish so to me it's a no brainer. Basically the ardunio is a set of microcontrolller boards that have the same boot firmware so the software will load to any of their boards.

After a gander I ordered a nano version to go in the dome with the compass chip and bluetooth chip. The uno version that's coming will go in the garage to monitor if the door is up or down and I have found an iPhone app to drive it across a wireless network. I also found a code example so it will email me if the door is open too long.

All these bits are cheap as chips off ebay from china and you can get them to do almost anything.

The red chip in the pics is the compass. It's from the UK.

But to show my support for greece I've switched from Buirbon to Ouzo

More to come on this one.

[rcheshire (Rowland)]

The heart and soul of my imaging kit, presently. Easy enough, even for beginners.

[kustard (Simon)]

I've played with atmel (arduino) MCU's and they are good to use. For the little project I made up I ended up using a PIC based kit as I had the programming gear already.

http://www.iceinspace.com.au/forum/s...ad.php?t=97639

They certainly make designing and making a control system very easy no matter which one you use.

[Tandum (Robin)]

The arduino boards arrived today. The nano version in the pic is just so much smaller than the uno, yet has more or less the same functionality. Only real difference I can see is it only supplies 3.3v if running on USB power. Won't be an issue here.

The uno arrived early and I had the compass chip and the bluetooth working with it in about 15 minutes. I wrote up a small app for the PC to read headings from the bluetooth serial port, correct for mag offset, and feed the heading into poth dome. I thought I might have to store and average readings but it only seems to wobble around about .5 degree on the bench. It should work just fine.

The nano board arrived after lunch and I simply swapped boards and almost everything worked. The bluetooth seems to have a large send buffer and it was writing to it faster than I was reading. I changed the code so it would only send a heading if I requested one. All good, so off to jaycar for a box and a battery bits tomorrow.

[edit]
I see on stargazers they use an arduino to drive an easydriver board via ascom to control steppers for focus control. I'll have to look into that.

[2stroke (Jay)]

The cheat sheet should help http://robodino.org/resources/arduino , will have to grab one myself to tinker with for some fun, really wont a pi first to play with though.

[Tandum (Robin)]

That'll be handy Jay, about 12years ago when I did this stuff for a living, we had object charts hanging all over the walls. You sort of get used to the paper version. It has been a bit hard to pick it up again without that to be honest

This new visual studio I'm using now doesn't even have a built in help file, it takes you on line to MSDN. Satan's Sanctuary
But, I have managed to build a working ascom driver for an SX serial wheel .. Yahhh.


The compass project however has failed. The enormous stratco roof hanging off the back of this house warps the field too much. The compass is off by almost 40 degrees to the south east but correct to the north west. It will not fix my pointing issues in the dome. At least I believe it's the steel roof causing the issues.

Anyone want a compass chip to play with?

The other parts are now in a garage automation project to use iwup from an iphone to control the garage and the bluetooth bits are for either the mount or the wheel.