Advanced Servo Mixer powered by Arduino.

I have recently began playing around with RC planes and helicopters and like most things I delve into I find limitations on things I want to do but I am unable because the products offered for the masses are limited.  This is typically because they tend to sacrifice complexity for ease of use.  In this case I require a servo mixer that can do conditional mixing.  The following video might illustrate my needs a little more clearly.

Currently I have been able to find 2 types of commercial servo mixers on the market.  The first I'll call a "dumb" type which simply takes 2 inputs and mixes it to 2 outputs.  This isn't to say the product is bad, it definitly works well for what it does, I am just calling it "dumb" to say it has no configurability.  The second type is made by Desert RC.  This mixer is a little better in that it is programable and can be configured for custom mixes, but you are limited to using their configuration utility and there are limits.  While the desert RC mixer is a fantasic product it will not work for my needs.

I have decided to try and build my own servo mixer that will be based on Arduino.  The type of mixer I am making would never work for the masses because to configure it involves writing code.  By writing code, I will have total control over how the mixer process input commands and passes them to output commands.  In my case I am sacrificing ease of use for complexity.

Here is a video overview of the current draft of the schematic I am working on. (Best to watch in fullscreen 1080p in order to see all the schematic symbols)

As always feedback is welcome.

Update on Wednesday, November 30, 2011 at 07:00PM by Damage

I have let the autorouter churn on routing my board 24/7 for literally 7 days.  It has yet to complete the route.  I am beginning to think I need to relax some of my design tolerances.  I might try shuffling some tracks around and attempting another pass.  Here is a screenshot of FreeRoute after 145,000+ routes.

Update on Thursday, December 1, 2011 at 07:10PM by Damage

Ok, I was able to shuffle some things around and I can now announce that I have a successfull route (woot!).  I have now ordered 16 boards from batchpcb and should expect them sometime in mid-december.  I also ordered enough componenets from mouser to build out 8 of these boards.  If anyone is interested in a sample, I'll gladly ship one out if you cover costs (Materials + Shipping, not charging for my assembly labor).  I'll have to work out what the true cost is, If I had to guess off the top of my head I would say around $10 or so in materials, but I would like to double check that.  Anyhow  Here is an image from cad of the boards on order....  ignore the dashed line on the perimeter of the boards, this represents a ground plane.  On the actual boards, all the empty (black) space will have a copper pour connected to ground to help mitigate interference.  The goal is to make the boards as small (and light) as possible.  The dimensions are 1.25x.75 inches.  Slightly larger then a postage stamp.

***click on the image for a larger view***

Update on Friday, December 23, 2011 at 06:35PM by Damage

Christmas came early for Damage-Designs.com Today the post office has delivered the servo buddy circuit boards I ordered from BatchPCB.  I hope to over the holiday break be able to populate one of these boards and start testing code.  It's one thing to see it drawn up in computer renders, but it is much more exciting to have the physical boards in hand.

Here are a few photos of the boards.

Comments

[ilovefpv]

Great post.. I've done something very similar with an ARM7 (LPC2103) core... Thanks for sharing!

[Damage]

I would love to see what you have done.

[Rick Harms]

I have been working on a similar project. I searched Google so that I would not reinvent the wheel. This is what I want to do, with the exception of a few more inputs and outputs. Should be simple. Now, are you selling and of the boards. I am thinking of a purchase to use as a test board. This would assist me in my small steps method.
I also have ideas on the code, but if you have any samples, that would be terrific.
thank you
Rick Harms
rick@inharmsway.org
rick@harms-family.com