Futaba M6 Fr Sky 2.4 ghz DIY Conversion

[Paul Luby]

Hi DG3

Be nice to see a Digifleet on the flying field again.

To mount the Nano I tend to use a pair of 15 socket headers soldered on strip board.

Glad you found the code easy to work through. I could have used FOR NEXT or DO WHILE to shorten the PPM assembly section but there was loads of memory remaining.

You've probably worked it out already but removing the serial output lines from the code prior to final writing to the Arduino will make the PPM cycle occur about every 20 milli seconds which is fine.

I'm revising for an exam at the minute. I've not posted other electronics projects I've done cause people tend to be buy and fly merchants nowadays. I have to sort a lot out to make the other stuff post able but as I'm revising for an exam and trying to find a job given I leave the RAF in Aug after 30 years service it may take a while.

Paul

(AKA Veri-Gash)

[DG3]

Cheers Paul. Good luck with the exam and finding a new job.

[Paul Luby]

DG3

Regards Oscilloscopes, I acquired one that was being scrapped many years ago and got in working. When it finally died 2 years ago I got one of these off e-Bay.

http://www.uni-trend.com/UT81B.html

Its not the be all and end all of scopes as it only has a bandwidth of 8 MHz, so looking at our 2.4 GHz output frequencies is out. For general use I find it ok and it was less than 100 quid. Type scopemeter into e-Bay, there's quite a selection at a range of prices.

I fancy one of those Hantek 200MHz bandwidth 2 channel scopemeters but being a Yorkshireman I can't justify it.

Paul

(AKA Veri-Gash)

[David Ashby - Moderator]

Hi Paul, just catching up and welcome from me, that looks interesting.

[Paul Luby]

Hi David

What about one of these on 2.4 ghz, the Digifleet is factory fresh and fully functional.

[DG3]

Hi Paul,

For my Fleet Tx project I found an Arduino Micro with 20 digital IO pins, 12 of which can be used as 10 bit ADC. I have one on order.

**LINK**

I was telling a man in our club what I was doing and he very kindly donated two TX's one of which is an old skyleader job. Check out the bird guano. It cleaned up nicely and internals seemed fine. Ready for another Arduino (Nano will do fine).

[Paul Luby]

Hi DG3

Wow, that did clean up well.

The old saying "they don't make them like that any more is right on"

The black Digi fleet set I got off e-bay is literally factory fresh and was found in an attic.

It has that new faux leather and new unused electronics smell. I'll upload some pictures soonest.

The RCM&E set while technically awesome for its time never looked expensive, neither did the Micron set. They have both cleaned up nice but nowhere near as good as your Skyleader.

Its nice to see old gear being used again.

Paul

(AKA Veri-Gash_

[Paul Luby]

Hi Guys

Here's some pictures of the Digi-Fleet Custom III set I got of e-Bay.

The batteries charge up and it all works when connected. The servo's are unmarked and I suspect have never been installed in a model. Even has the original receipt and service receipts from Fleet Control Systems with it.

I think I gonna modify this one to 2.4 ghz last.

Its really is factory fresh.

Edited By Paul Luby on 01/05/2014 22:59:59

[Paul Luby]

Hi Guys

I just done the last modification to the Futaba M6 that I plan to do to it.

To stop me having to take the back off it when I need to charge the battery, I've made a lead that connects to the battery balance connector and ends in a charge socket that is accessible from the out side of the case.

The charge socket has a pin location that is blanked off and the charge/balance lead has a pin missing in the same location to stop the charge/balance lead being connected the wrong way round.

I've uploaded pictures of the above mentioned items so you can copy them if you want.

Enjoy.

Paul

(AKA Veri-Gash)

Charge Socket External View (above)

Internal View Of Charge Socket And Lipo Connection Lead (above)

Charge / Balance Lead (above)

[Chris Bott - Moderator]

So, what do you think? This looks worth a punt on an FrSky hack module at least? Just for use with the odd vintage model.

My first ever proportional Tx, just fetched it down from the loft.

[Paul Luby]

Chris

Go on mate, mod it up.

Reference my Futaba M6 2.4 ghz mod, I bumped into Alex Whittaker at the RAFMAA Warbirds Over Wittering. He took a few pictures of the Futaba M6 2.4 ghz set and of the other Tx's I am planning to mod up.

A few RAF guys are now making the same point you've just raised.

Why not a class of old Tx's (converted) being used fly old style aerobatic models such as the link below.

Georgia Peach

Sounds good to me.

Paul

(AKA Veri-Gash)

[Chris Bott - Moderator]

Nice, I wonder if the UKCAA guys would be keen? Type that in the search box above, there's quite a few threads.

They have a website too, HERE

[Chris Bott - Moderator]

But to be honest, I'm thinking more like these.

[Paul Luby]

Hi Chris

Its amazing how many niche groups there are in this hobby of ours. It never ceases to surprise me.

Paul

(AKA Veri-Gash)

[Chris Bott - Moderator]

By the way, I've found a pulse train in the Waltron, at the bottom of a pull up resistor between what's clearly the encoder section and the RF section.

What looks like a buddy connection on the front is one, but not as we now know it. It acts as a charge socket when the switch is off, but the third pin applies power to the Tx. So with a crossed cable between two of these, one would be powered with it's switch on, then switching it off would power the slave (pupils) Tx.

It's a shame that the meter on the front measures RF output power. Without a 27Mhz crystal in place, it reads nothing. So I may have to alter that, or just ignore it.

The trims, are mechanical, only 4 pots in this one.

[Paul Luby]

Are the Waltron encoder and RF sections on separate PCB's as removing the RF PCB might you a little more space.

If their combined my instinct is to remove them and do and Arduino encoder.

There are ways to make the meter indicate, though it would be a false reading. Depends how deep you want to go.

I spent a couple of hours looking over a mates Digifleet XP/FM as he wants to convert it to 2.4 ghz. Cause they used to use Op-Amps to reproduce the modern rates, mixers, etc functions and it was really crowded in there.

Found his encoder output and showed him where to cut the tracks to isolate the RF section.

We could be starting a trend here.

[Chris Bott - Moderator]

It's a combined board. But there's loads of space below the gimbals. So I'll see how the RF module fits before I decide. It's great to have options though.

[Paul Luby]

Not a microchip in site, lovely.

Dig those hand wound inductors and the transistor heat sink.

Edited By Paul Luby on 08/05/2014 21:33:14

[Chris Bott - Moderator]

And there's the holes in the PCB for the optional 5th channel

[Paul Luby]

Sounds to me like that there Waltron is getting modded up.

[Chris Bott - Moderator]

Hi Paul.

News is that the Waltron PPM that I located, isn't suitable to drive the FrSky module. It's not very stable either.

So, with a Nano from Ebay I have, after a fair bit of frustration, got the PC talking to it.
I can upload sketches into the nano and have even progressed to altering some of the simple examples that come with the Arduino PC package.

I've loaded your coder sketch and can read the serial calibration numbers.
I recon I have an idea how each part of your sketch works. I think I've even worked out how to do all the calibration.

Now, I want to be fiercely independent and learn about these things, from complete zero knowledge, as I go. But I have to ask just a couple of questions.

1. I see black and white wires running round all the pots in your Tx. These must be taking a voltage reference to them all. Is this just battery volts? Or as I suspect, a nice regulated 5V? If so, is that a 5V reg on your veroboard?

2. I can work out all the connections, supply volts, ground, A0 - A3 inputs (all I need) and the PPM out pin. Can I leave everything else unconnected to anything?

I'm sure there will be more, but I'm trying to do as much as I possibly can myself - I like the challenge.

PS - I just found a pin called AREF whch is an analogue reference voltage. Maybe this pin is the ref for the pots?

Edited By Chris Bott - Moderator on 24/05/2014 11:07:09

[Paul Luby]

Hi Chris

Never did a schematic for the Futaba as I was working from in me head so to speak.

So I just sat down and did you a quick schematic, below (Please note, I used white wire for my positive leads cause that was what I had in stock at the time, the diagram below uses RED).

Diagram moved to later post.

The Arduino Nano works on an input voltage of 7 - 12 volts on the pin marked VIN.

The use of the 2 forward biased diodes prevent my 3S lipo from over volting it even by a little.

The Fr Sky DIY Module uses 6 - 13V so thats in limits also.

The Nano puts out a stabilised 5V for supplying sensors with a regulated supply. I use this to supply the pots and connect the other side of the pots to the negative rail.

Tthe sweeper arms on the pots are connected to the respective analog inputs on the Nano.

Th 1k resistors are used to tie down the digital inputs to stop them floating and given erroneous reading when they are not switched on so to speak and the switches apply the 5V to pull them up.

Anything not used you can leave disconnected, that the beauty of the Ardiuno's.

Please don't play with the AREF. The Ardiuno is configured by default to accept an reference voltage of 5V which it turns into a digital value from 0 -1024. The AREF allows you to tell the Analog input that you are using a different reference voltage between 0 - 5V. Messing about with this can cause damage to the Arduino, so unless you really need to use it because for example a sensor you are using only generates a max of 3.3V, then my advice is not play with the AREF pin.

Hope all this helps.

Paul

(AKA Veri-Gash)

Edited By Paul Luby on 24/05/2014 12:53:07

Edited By Chris Bott - Moderator on 24/05/2014 16:07:32

[Chris Bott - Moderator]

Brilliant, thanks Paul.

I'm pretty sure that's everything I need.

(except a thanks button here.)

[Paul Luby]

Hi Chris

Updated the schematic but the forum won't let me edit to insert updated schematic. So I've put it here, really frustrating. The new one is just better laid out.

Paul

(AKA Veri-Gash)

Edited By Paul Luby on 24/05/2014 16:05:49

[Shaunie]

I put an Frsky DIY module in an old Futaba Challenger Tx about six Months ago. I use it on an electric trainer, just like the old days but without the peg!

Shaunie.