Saturday, December 29, 2012

er9x Tutorial: Mixing (good for Turnigy 9xr)

Here's some notes to go along with the tutorial/video for er9x mixing.  Some people have said that they thought er9x was more complicated than traditional Tx software, but in many ways I think it's simpler.

Here's a few examples that should cover most of what you need to know to make good use of the mix screen, with accompanying video tutorial. (longer version to be uploaded later)

Mixing a Stick to a Channel

This is the simplest mix you can make.  Here's Channel 1, mapped 100% from the rudder (the "source").  The "+" is just a redundant note that  it's positive 100%; all percentages are shown with the sign.
  • CH01 +100%RUD 
Set this up, and you'll see the servo attached to channel 1 moves with the rudder stick.

The default 4-channel model definition is nothing more than the four sticks mixed to the first four channels.:
  • CH01 +100%RUD 
  • CH02 +100%ELE 
  • CH03 +100%THR 
  • CH04 +100%AIL

Mixing a Stick to Two Channels

Now let's do something that's not especially useful in a practical sense, but will be handy for this tutorial.  We'll map the rudder stick to two output channels.
  • CH01 +100%RUD
  • CH02 +100%RUD 
Moving the rudder stick now moves the two servos attached to channels 1 and 2.  In some of the following examples, we'll modify channel 2 and leave channel 1 unmodified as a reference.


There's a reversing option on the Limits menu, but it's not really necessary.  We'll reverse channel 2 by changing the +100% to -100%.
  • CH01 +100%RUD
  • CH02 -100%RUD 
Now the two servos move in opposite motion.

Reducing Rates

Change channel 2 to +50%.
  • CH01 +100%RUD
  • CH02  +50%RUD 
Now the two servos move in the same direction again, with channel 2 at 50%.  Of course, you could have a reversed lower rate throw by making the percentage negative.

HALF and FULL: Confusing yet Powerful Switch Controls

In order to do anything with switches, we'll use the HALF and FULL inputs.  By themselves, they don't do much of anything.  Let's channels 1 and 2 to to the sources HALF and FULL, respectively:
  • CH01 +100%HALF
  • CH02 +100%FULL 
This results in both channels 1 and 2 being output at a value of 100%.  Not particularly useful, so let's mix in the GEAR switch to both of these.  Keep the default Multiplex setting of ADD.

  • CH01 +100%HALF Switch(GEA)
  • CH02 +100%FULL Switch(GEA)

Now we see the channels acting like switches.  As we toggle the GEAR switch, we see channel 1 switching between 0% and 100%; channel 2 switches between -100% and 100% (just as we typically want most switches to behave for real).

So, what's happening?  Unlike a stick which varies smoothly from -100% to 100%, HALF returns either 0% or +100%, depending on the switch.  Likewise, FULL returns either -100% or 100% (the exact value can be modified by the Weight: parameter, but we'll just use 100% to keep things simple).

So, with the GEAR switch specified, the channels output -100% and 0% respectively when the switch is off, and both output 100% when the switch is on.  To reverse any of the switches, just select the switch name that starts with "!", such as "!GEA".

Setting up a Switch

So, the standard way to set a simple on/off toggle switch is to use the FULL input.  For example, to map the GEAR switch to channel 5, we would do this:
  • CH05  +100%FULL Switch(GEA) 
Note that you can specify a delay and a speed in seconds.  The speed is especially nice for things such as flaps and landing gear, since you can get a smooth scale operation.

Mixing a Stick and a Switch ("throttle enable")

Now let's mix a stick and a switch.  As a practical example, we'll set up the THR switch to enable the throttle stick.  If the THR switch is off, the throttle stick is ignored. This is a good safety feature; when you're plugging in your batteries or carrying the model before you've unplugged your batteries, you won't have to worry that the radio will bump your chest and spin up the prop.

To do this:
  • Map the throttle stick to the output channel, as covered above.
  • Specify the THR switch.
  • Set the Multiplex parameter to REPLACE
The Multiplex parameter can be one of ADD, MULTIPLY, or REPLACE.  We specify REPLACE so that when the THR switch is off the output value which would normally be specified by the stick position is replaced by -100%.  So, no matter what the stick position, the throttle can't be activated.
  • CH03   +100%THR
  •      R -100%FULL Switch(!THR)
Combining Multiple Mixes ("dual rates")

Finally, let's look at what we need to do to set up dual rates.  This is pretty simple.  You can add multiple mixes to the same channel.  The switch specifies which mix takes effect (it can actually be a lot more sophisticated, but we'll cover that later).  So, this mix:
  • CH01 +100%AIL Switch(AIL)
  •       +80%AIL Switch(!AIL)
follows this logic:
  • If the AIL switch is in the normal position, map the AIL stick at 100% to channel 1.
  • If the AIL switch is in the toggled position, map the AIL stick at 80% to channel 1.
The nice thing about er9x is that you can use a single dual rate switch to manage multiple channels.  You could repeat the above lines for the elevator and rudder channels, both of them specifying the AIL switch.

But Wait, There's More!

There's quite a bit more that can be done with er9x mixing, but this covers most of what you need to know.  If you're interested in seeing some more, drop me a line!


Lynxmotion sells Aurora 9 gimbals.  "these gimbals feature high sensitivity, 8 ball-bearings, and adjustable tension. You can enable or disable self centering on both axis and enable ratcheting on the Y axis."  Somebody mentioned they can be fit onto a 9x by removing a pair of tabs and soldering the wires.

Servo City has pin crimpers at a pretty good price.

FMS Simulator Universal USB Cable.

Sunday, December 16, 2012

Flying in the Rain

I've been chatting with Sean Headrick of and he brought over his latest thinshell model, the Hugo to fly.  It was pouring down rain, but no problem!  Everything but the props are enclosed in the body, including the motors.  There's an interior shelf that holds 2 3S 2750 batteries.  Sean gets about 20 minutes of flying around (not just hovering) with this.

The units look really nice, and are pretty light.  The frame is 440 grams.  It's two halves are permanently bonded together, and each arm has a hatch for accessing the motors and ESCs. There's a top shelf in the center for the flight controller, receiver, and any other electronics.  I'll be helping him with some testing and flight controller selection/tuning.

As a bonus, we did some crash tests.  Quite sturdy!  The last crash took a prop off and pulled a motor loose; Sean's got a new double-cup design that will strengthen up the motor mount.

Here's some videos... flying around in the rain, and then crashing the unit to see how much of a hit it could take.  To best see the rain, watch in HD!

Tuesday, December 11, 2012

Monday, December 10, 2012

APM2.5 Case on Thingiverse

Designer barneyj notes:
The mounting tabs were designed to fit on a Gaui 330x frame. I used micro servo mounting screws to screw the shell together. I made a cutout for the "ABC" status LEDs but I missed the "TX/RX" LEDs. I might incorporate it in the next iteration.

Friday, December 7, 2012

Weekly Miscellania is a highly regarded source for Walkera parts. $5 worldwide shipping.  Link is to the LB page.

Lightweight foam canopy replacements for nanoquads.  Cuts weight in half, made from 1/2in foam.

ServoCity has 2-axis spring-loaded joysticks... just the thing if your're thinking of making a tank-like controller!

Wednesday, December 5, 2012

It's a 3D world, and we're just printing in it!

Or rather we will be...  getting access to a Makerbot when it's delivered in January, so I'm going to stash some notes here.

  • Past experience:  Z Corp color printer, used to print the maquettes for our Zoetrope.
  • Thingiverse id: marhar.
  • Makerware here.  This takes your STL files and generates gcode which is sent to the printer.
  • What modelling software to use?  Around here everybody has of course experience with Maya.
  • Makerbot has a guide  that lists lots of options.  Chris Anderson uses 123D, so I guess I'll start with that.  If my stuff looks bad blame him!

Tuesday, December 4, 2012

EzFly R3 Released!

Motorhead has released a new version ("R3") of the EzFly.  It moves the motor forward and has an extended nose, both features which make it easier to get the CG forward.

EzFly Thread, check out the R3 plans in post 1.

FancyFoam has kits:
    Original - P51 - Spitfire
update: dead links... just go to!

blogodex = {"toc" : "EZFly", "idx" : ["motorhead", "Fancy Foam"]};