Saturday, April 26, 2014

Lua Coming in OpenTX 2

An interesting milestone is upon us.  Lua (the scripting language) will be embedded in OpenTX 2.

Here's an example of how elevon mixing would be expressed in Lua

local inputs = {
                 { "Aileron", SOURCE },
                 { "Elevator", SOURCE },
                 { "Ail. ratio", VALUE, -100, 100, 0 },
                 { "Ele. ratio", VALUE, -100, 100, 0 }
local outputs = { "Elv1", "Elv2" }

local function run(input1, input2, ratio1, ratio2)

  value1 = (input1 * ratio1) / 100
  value2 = (input2 * ratio2) / 100
  elevon1 = value1 + value2
  elevon2 = value1 - value2
  return elevon1, elevon2

return { input=inputs, output=outputs, run=run }

Although it should be noted the the docs explicitly say "Do not use Lua model scripts for controlling any aspect of your model that could cause a crash if script stops executing."

Thursday, April 17, 2014

Some Interesting 9xr/OpenTx History

Courtesy of Mike Blandford:

The original 9X, with er9x firmware, once it had the telemetry mods and the voice module I designed added, does all those things. OpenTx was forked from er9x some time ago, but many of the basic concepts are still the same. In particular, the mixer was originally designed by Thomas Husterer, who deserves far more credit than he generally receives. It was he who wrote the TH9X firmware with the mixer in. Erazz took TH9X and forked er9x, and later I added to er9x. 
Before the Taranis, there was also the Gruvin and SKY board upgrades for the 9X that provided a much easier upgrade method for the 9X to provide these extras. Having modified er9x for the SKY board (ARM processor) I was able to quickly write the low level drivers for the Taranis, much of which is still in the current firmware.
The Taranis and the firmware have just made this more accessible by being sold complete and ready. 
So please remember the history, and provide credit the originator "Thomas Husterer" for currently used concepts.
blogodex: History;

Sunday, April 13, 2014

The East Bay Taranis Switch Wrench!

 Over on the RCG Taranis thread there's been a couple of nice homemade switch wrench designs presented.  Here's our entry!

Not particularly fancy, just clip a large paperclip in half and trim to the appropriate size.  It doesn't take a lot of torque to tighten a switch pretty tightly.

blogodex = {"idx" : "Taranis Wrench"}

Sunday, April 6, 2014

LiPo Battery Charging and Storage

The Charming Mrs. EastBay RC puts up with a lot in the service of her husband's various hobbies, but one place where I'm pretty sure she would draw the line is burning down EastBay RC's international headquarters.  I've experienced first hand the rather unpleasant experience of having a LiPo battery short out and burst into flames, so I'm a stickler for careful battery charging, handling, and storage.
 Here's my main charging station.  That's a HobbyKing 4 port charger powered by an old PC power supply.  The charging bunker consists of a standard sized concrete block sandwiched between two flat blocks.  I painted everything white to look a little better and to keep dust, etc from coming off the concrete.  I've notched the block so that battery leads can fit in with the top closed.  There's a smoke detector on top, and a fire extinguisher next to my workbench.
 Here's my battery storage bunker.  It's a fireproof safe that I salvaged out of recycling.  It weighs a ton.  The unit was open with the door bolts set in the locked position.  I tried (unsuccessfully) to figure out how to set a new combination, but it works perfectly as a battery storage bunker.  The door is heavy, so I just need to be careful not to drop it on my fingers.
Here's a view showing some batteries.  One day when I have some time to kill I'll put some shelves in to make the storage a bit more tidy, but for now I'm really pleased with it.
Prior, I stored everything in an old ammo box, which was a bit more restrictive in space.  The Internet seems to think that it would be fine for containing the open flame of a burning LiPo.  Prior to that, I kept everything stored in a concrete block similar to my charging bunker.  I've also got some LiPo bags for use on the go.

Bottom line:

  • Take LiPo charging and storage safety issues seriously.  Watch some youtube videos on "lipo battery fire" to ensure that you do.
  • Get something to put your batteries in while charging.  I think a LiPo is actually a good solution, but it's a bit more convenient to have a larger bunker if you've got the space.
  • Always stick around while your batteries are charging.  I typically charge while I'm at my workbench so it's not a problem for me.
  • Keep a fire extinguisher nearby.  This applies to your workshop or hobby table as well.
  • Be careful, but not anxious.  I've never (thank God) been in a car accident, but I still wear a safety belt when I drive.  Same here... it's a bit overkill until the one time it isn't!
  • If this save you from burning down your place and getting in big trouble with the family, you owe me a verrrry nice dinner!
update: here's my bag of sand that I was using to cover the hole in the concrete block before I switched to the flat concrete block.  The reasons I switched were:
  • I wanted to move the charging station from the garage to my workshop so it would be a bit easier to attend to.
  • I was in deathly fear every time I handled the bag, afraid it would split open and I would be vacuuming sand for hours.
  • After watching a couple of youtube videos I think the concrete topper will contain any open flames.

blogodex = {"toc" : "Battery Safety", "idx" : ["Batteries", "Charging", "Safety", "Battery Bunker"]};

Thursday, April 3, 2014

On The Waterfront

I went with some coworkers on a field trip to Autodesk's amazing Pier 9 workshop.  It's the same space where Instructibles has their office.  There's a great overview of the space here, but I took a few pictures of things that caught my eye to post here.  The Autodesk people were great hosts and really sharp people.
As I recall, they have six or eight main areas... woodworking, kitchen, metalworking, milling and cutting, whatever it is that 3D printing and laser cutting is called, electronics, and sewing.  There's a mold-making room as well.  On this shelf are a few of their interesting projects.
Here are some records that were made by laser etching maple disks.  I missed the name of the person that made them, but she had some 3D printed records as well.  The key insight was taking an audio file, pulling the waveform, and mapping that onto the disk.  Neat!
Norm Abram would approve.  There's a bin of safety glasses at each of the doors.
Here's the water cutter.  It can cut through 4 inches of steel plate.  Current software for driving these kinds of devices is not particularly sophisticated.  You could give a toolpath that would cut the machine in half and it would cheerfully execute it.
A 5 axis CNC milling machine.  I'm not sure if the picture shows the scale very well.  That's the second floor walkway at the top left.
Here's their library of milling bits.  The big machines are a bit out of my brain space, but having bought router and shaper bits all I could think of was "wow that's a lot of money in that drawer!"  There's a machine that heats the bit holders so that when the bits are put into place the metal contracts and holds everything tight.

The control panel for one of the milling machines.  They're working on networking all the machines together.  Traditionally there hasn't been a lot done in that space, since a machine might be bought to manufacture a certain part, and will run the same program for years on end.
The woodworking shop.  Smells good and splendidly dust free!
As you are trained and checked out on each machine you go into the database.  Each machine has a keycard reader for access.
In the wood shop. Background, that cabinet is filled with fasteners of all shapes and sized.  Foreground, some amazingly talented and cool coworkers.
The metal shop.
Old fashioned 2D printing!
My lust burns bright, with the intensity of a 400 watt laser beam!
They had a shelf of interesting projects to show visitors.
This was 3D printed from a topographical map.
Some 3D printed models.
Whatever might go wrong, they'll know about it right away!
3D printer.
The second floor garage door.  Below is the driveway into the Pier 9 building.
As it was explained to us, these 3D printers are resin based.  The laser light cures the liquid resin.  I had hoped to see how the finished model was removed and cleaned (is it dripping with liquid resin?) but wasn't able to.
These were some of the things on the demo shelves.
This planetary gear was 3D printed in one piece. Check out the video below to see how smooth it is.
This tank chain was also printed in one piece.  I'm not sure about how the treads were attached.  It would be cool if they were printed in place as well. I made a quick video of this as well.
Here's the result of a project done in cooperation with UC Davis.  It's a print based on an MRI scan or somesuch of a horse tendon.
Here's the view from their sewing room.