post last updated on 20150201

please regularly check the V3 documentation file for current build status. JohnRB maintains an Open FlightStab News section with updates.

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JohnRB Update 20141226: Updated OFS Firmware

Open FlightStab firmware has been updated to add support for Graupner and Multiplex SRXL. The firmware changes made by user ingo_s have been merged into the project. The Builds include Hex files for many of the different boards that OFS supports. Only the 2 RX3S V2 SRXL versions have been test by ingo_s.

If you wish to use a version other than those tested, do a very through ground test before flight.

The documentation has also been updated.

Source and Hex files link.

Documentation Link.

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Original Post

starting this thread to discuss the development of an opensource flight stabilizer. i started this project after looking at various flight stabilizers and also getting the HK RX3S. i didn't like the performance of the V1 device (non-linear VR gains, no remote AUX gain control, stabilizer fights me on aerobatic manoeuvres). so, the goal is to hack the RX3S V1 and V2 and replace them with better firmware.

JohnRB and i currently maintain the master branch for the flightstab firmware.

• "v3" build date stamped 20140322. the code is found at https://github.com/noobee/FlightStab/archive/master.zip and the v3 documentation is found at https://docs.google.com/document/d/1...f7nH9Qs1dY/pub
• the documentation for builds before 20140322 is found at https://docs.google.com/document/d/1...oZjQA22QQQ/pub
• in general, the source code and builds are found at https://github.com/noobee/FlightStab

ckleanth has also helped very much with documentation.

LazyZero has a flashing tool that simplifies flashing devices http://lazyzero.de/en/modellbau/kkmulticopterflashtool

there is also a nice blog of a walkthrough with pictures on how to program the RX3S devices and a flight report from mikejr83 at

• http://blog.itsnotfound.com/2013/08/...e-orange-rs3x/ and
• http://blog.itsnotfound.com/2013/08/...ilizer-update/

Clive Hall has also written a nice doc describing the HKFactory and the OpenFlightStab versions at http://www.cbhmodels.co.uk/rx3s.htm

and thanks to many others in this thread that have suggested great ideas along the way.

standard disclaimers apply. please review and use it at your own risk. i'm not responsible if you bricked your plane, lost your RX3S, or both

RX3S V1 connections:



RX3S V2 connections:



NanoWii connections:

following

...

I want to support the flaperon:-)

Originally Posted by Yashiro

I want to support the flaperon:-)

as long as you have 3 servo inputs this wont happen mate

Originally Posted by Radio.Active

Well I have 2 of them that I don't like and I'm prepared to Zap them.

... Alan

let us know if you try to update the firmware? i've documented the steps that i took to flash mine. hope the notes are sufficiently detailed. i'll revise/update them as needed.

Originally Posted by Yashiro

I want to support the flaperon:-)

ah, ok then we need another AIL-IN channel.

interestingly, this is probably much easier to do on the RX3S V1 than on the V2, since the ISP connector pins are exposed and can be repurposed for RX use. i'll update the first post to maintain a feature-request list.

Originally Posted by noobee

let us know if you try to update the firmware? i've documented the steps that i took to flash mine. hope the notes are sufficiently detailed. i'll revise/update them as needed.



ah, ok then we need another AIL-IN channel.

interestingly, this is probably much easier to do on the RX3S V1 than on the V2, since the ISP connector pins are exposed and can be repurposed for RX use. i'll update the first post to maintain a feature-request list.

bugger I sold off all my v1 modulles
argh!!

Originally Posted by ckleanth

bugger I sold off all my v1 modulles
argh!!

with the v2, you probably need to mod the board a little, to run a wire from a dip switch (just too many dip switches on the v2).

on the upside, the v2 has all the IO needed for a quadcopter (4 in and 4 out)

Originally Posted by noobee

with the v2, you probably need to mod the board a little, to run a wire from a dip switch (just too many dip switches on the v2).

on the upside, the v2 has all the IO needed for a quadcopter (4 in and 4 out)

just a few comments
with the v1 you have three dip switches, i havent checked your code but if you use two dip switches for your check loop then you can have six combinations for operation modes.
clever idea the reversing function using the gain knob but how sensitive is the gain adjustment because of the available knob rotation. have you changed the max value?

with the v2 yes a lot more dip switches (I dont have a module yet but I think its five)
again if you use two dip switches for your check loop then you can have ten combinations for operation modes (if you want).
for normal mode the aux woud have the off/on function
for flaperons you can use the aux as input so you wont have the off function without mods
for quadcopter 4 in 4 out as you said but so you wont have the off function without mods
vwing delta etc requires mixing

btw do you have enough memory on the cpu ?

with 2 dip switches, i think there would be 4 combinations. assuming "1" is in the rev position, the settings right now are:

(rud, ele)
(0, 0) NORMAL
(0, 1) VTAIL
(1, 0) DELTA
(1, 1) DELTA

i could use (1, 1) for NORMAL-FLAPPERON, which would reassign the pinouts to include another RX AIL2-IN. @yashiro, do you use flapperon in normal mode (eg. 3d planes) or vtail mode (eg. gliders)?

if you want flapperon with the v1 device, you can use two ISP pins for AUX-IN and AIL2-IN. if you want flapperon with the v2 device, you probably need to solder a wire from one of the dip switches for AIL2-IN (since V2 already has a AUX-IN pin).

the VR knobs are quite linear now compared to the RX3S V1 implementation. i heard the V2s are better. HK must have fix the errors due to integer division.

right now, memory use for the RX3S is around 9400 bytes (out of 14000+), so there's still plenty of space. i could also use simpler implementations of the i2c library and itg3205 (gyro on the RX3S) to reclaim space if need (not at this time).

Originally Posted by ckleanth

just a few comments
with the v1 you have three dip switches, i havent checked your code but if you use two dip switches for your check loop then you can have six combinations for operation modes.
clever idea the reversing function using the gain knob but how sensitive is the gain adjustment because of the available knob rotation. have you changed the max value?

with the v2 yes a lot more dip switches (I dont have a module yet but I think its five)
again if you use two dip switches for your check loop then you can have ten combinations for operation modes (if you want).
for normal mode the aux woud have the off/on function
for flaperons you can use the aux as input so you wont have the off function without mods
for quadcopter 4 in 4 out as you said but so you wont have the off function without mods
vwing delta etc requires mixing

btw do you have enough memory on the cpu ?

Originally Posted by noobee

with 2 dip switches, i think there would be 4 combinations. assuming "...

made sense when I thought it, doesent make much sense now..

Originally Posted by noobee

.if you want flapperon with the v2 device, you probably need to solder a wire from one of the dip switches for AIL2-IN (since V2 already has a AUX-IN pin).
..

why you need to do this?

Originally Posted by noobee

i could use (1, 1) for NORMAL-FLAPPERON, which would reassign the pinouts to include another RX AIL2-IN. @yashiro, do you use flapperon in normal mode (eg. 3d planes) or vtail mode (eg. gliders)?

hi,

It considers using by glider.
A flaperon is important.
The priority of V-tail is low.

Originally Posted by ckleanth

why you need to do this?

the v2 has 4 input (ail, ele, rud, aux) and 4 output (ailL, ele, rud, ailR) pins.

to support flapperons, you would need another input (ail2) pin. this extra input would probably need to come from one of the 6 dip switches.

Originally Posted by Yashiro

hi,

It considers using by glider.
A flaperon is important.
The priority of V-tail is low.

ok, i'll set

(rud, ele)
(0, 0) NORMAL
(0, 1) VTAIL
(1, 0) DELTA
(1, 1) FLAPPERON (normal tail)

flapperon mode would probably remap the pins to use 2 pins from the isp connector (miso and mosi), one for AUX-IN and one for AIL2-IN. AIL-R will then keep its original function as AIL-R OUT.