RC India

RC Equipments => Radios and Receivers => Topic started by: Dipanjan on May 08, 2016, 09:09:43 PM

Title: DIY Transmitter
Post by: Dipanjan on May 08, 2016, 09:09:43 PM
Hello everyone,
A few days back I bought a non working FS-T6 from Satya Gupta of Quadkopters. It was delivered pretty fast. I have taken it apart and was checking the motherboard. The TX turns on, detects throttle up, and makes various other sounds. But there is nothing in the LCD. I discovered the 7805 Voltage Regulator, 3.3 V Voltage regulator and the ARM chip (32F100) all are getting pretty hot. I suspect that the ARM chip might already be fried. So I guess there might be some kind of sort. I am trying to find that out, so that I can repair it.

Meanwhile,the sticks on my RCB6i are getting sloppy. They don't return to the Exact center and as a result my quad drifts away. I don't know if I had this problem from the very beginning,as I have recently discovered it from the EZ Ground station Radio view Option for Multiwii. before this I have only successfully flown a mini floater using this TX, it had some sort of offset for the Rudder(Channel 1).

So,I was thinking if I upgrade the FS-T6 with Arduino and use the RF module of the FS T6, or use OpenTx, would that be possible?
Now as far as I understand all the Transmitters out there have some sort of RF module in them ,that has only one input and that takes PPM signal. So all the Stick values are mixed in a single channel and then again decoded at the Receiver end. Generating The PPM signal would be easy using the arduino, but there are several questions I have in mind.

1. All the Rx Tx have bind feature, right? That means both the RX TX agree to insert and decode some sort of "Unique ID" into the PPM stream, so that they can recognize each other. Even if I generate the ppm signal with the arduino , I won't be able to use a FS-T6 receiver ,cause it won't bind, as the "Unique ID" is unknown to me. Can anyone shade some light on this?

2. Or,I can use OpenTx along with OpenRx. Will these two bind with each other? If I only generate the PPM signal stream using the Arduino?
Does anyone here have any experience on using Open RX-Tx modules?

3. What would be the approximate range of the 100mW 2.4GHz Open Tx Rx combo? Does anyone have any idea? I am asking this because if the range is still 1km, it won't be worth the effort and money spent.

So,please, anyone with any knowledge regarding this, comment here.  :hatsoff:
Title: Re:
Post by: a3ruz on May 08, 2016, 09:23:11 PM
Search in RCI , there's  thread by akhilzid
Title: Re: DIY Transmitter
Post by: Dipanjan on May 08, 2016, 10:50:05 PM
Thanks a lot a3ruz, have mailed him for some help.
Title: Re: DIY Transmitter
Post by: Dipanjan on May 08, 2016, 11:13:14 PM
I think I was wrong about one thing, the binding thing is handled by the rf moule itself, not by the microcontroller(in the Motherboard). So I might be able to use the Fly Sky RX module with this  after I replace the mobo with Arduino :D
Title: Re: DIY Transmitter
Post by: Balakrishna Reddy on May 08, 2016, 11:20:13 PM
The transmitter module in Fs is a7105 so once go through its datasheet. It will help a lot
Title: Re: DIY Transmitter
Post by: a3ruz on May 09, 2016, 05:38:59 PM
Sir i searched for the data sheet , n what i got was Chinese one , can you please post the link to English one
@Dipanjan  , there will be a way for binding   , may be a few lines of code / a physical switch  ,


" The Flysky protocol supports up to 12 channels, and both auto-binding and manual-binding. If Fixed ID is set to 'None' the transmitter will attempt to auto-bind with the receiver every time it is powered on. If a value is set for Fixed ID, the receiver must be bound manually one-time using the 'Bind' button, after which it should stay bound. "


  Link  (http://www.deviationtx.com/manuals/html-devo10/ch_protocols.html)
Title: Re: DIY Transmitter
Post by: Balakrishna Reddy on May 09, 2016, 06:18:03 PM
http://opendevices.ru/wp-content/uploads/2015/02/a7105.pdf
I hope this is it you are looking for. Try to google it you will get it. There are plenty of posts how to use this chip for communication.
Title: Re: DIY Transmitter
Post by: v2 eagle on May 09, 2016, 07:05:07 PM
you can still salvage everything except the motherboard and use it with open TX with arduino and a lcd. i have the LCD mentioned in Open TX and looking to build something in the near future but have no time, so ill help you with most of stuffs i have researched so far to save ur time.

binding is done by tx module, there will be connection between module and the mother board which is a PPM signal. the circuit of open tx is also PPM.

Let me know if you need anything else.
Title: Re:
Post by: a3ruz on May 09, 2016, 09:18:08 PM
@v2 so for entering in to binding mode a ppm signal is send to the tx module right ?
Title: Re: DIY Transmitter
Post by: v2 eagle on May 09, 2016, 10:28:46 PM
for a fs Th9x, the radio dont interfere in binding and solely by radio module i guess as there is no such option in radio for the same, and you have to play with the switches in the radio module for a bind, so my theory is that the radio simply converts all the gimbal inputs into ppm signal.

btw, for how much do you bought the radio for and does he has anything left in stock?
Title: Re: DIY Transmitter
Post by: Dipanjan on May 09, 2016, 11:20:25 PM
Hello, thanks for the response. The bind "switch" on the tx connect directly to the RF module, so I assume that the RF module handles the binding process all by itself (Unlike the RCB6i where the bind is done via software, i.e no hardware specified button).
I am thinking of trying the Open Rx Tx Module. They are also 2.4GHz, and I am comfortable with the arduino side. But the thing to consider is the cost, if I replace the mobo with the Arduino board, and send ppm signal to the RF module, then I would only have to buy the FS T6 receiver, costing around Rs. 900. I don't know what range to expect from it though.

And If I use Open Tx Rx module then the cost goes to 3500 for those two only. That should give me 1.5 Km range (as specified by the vendor, he could go 1.5km and still have solid signal, haven't checked further though).

Now which way do you suggest?

One more thing is that, I would need to use a LCD as output. But I can't find one that perfectly fits the FSt6 enclosure, AND is easily supported by Arduino(Libraries being available, else it would take much more time). I have already bought https://www.fabtolab.com/128x64-graphic-LCD-module-blue?search=lcd&page=2 (https://www.fabtolab.com/128x64-graphic-LCD-module-blue?search=lcd&page=2) but the LCD is quite large, and doesn't fit well. There are several alternatives like using Nokia 5110 LCD, but it won't fit the space . Will have to manage something for that.

Thanks again for your response. Please share your views.
Title: Re: DIY Transmitter
Post by: Dipanjan on May 09, 2016, 11:38:00 PM
The open tx module is a 2.4 ghz 100mW one. anyone have any experience with these? Any comment about range? Asking this because if I am going to pay 3500 for the rf modules, another 1000 for the Arduino LCd and other stuffs, and still get a range that any commercial radio gives around that price, I think I will opt for the commercial radio.  :giggle:

Regards
Title: Re: DIY Transmitter
Post by: v2 eagle on May 09, 2016, 11:59:04 PM
can you put here the link for the same.
Title: Re: DIY Transmitter
Post by: Dipanjan on May 10, 2016, 12:15:08 AM
Tx http://hobbysea.com/products.php?376&cPath=8&sid=8df79bbdc0b64716f977df289a47124c
Rx http://hobbysea.com/products.php?162&cPath=8&sid=8df79bbdc0b64716f977df289a47124c

for the radio, I got it for 660
Title: Re: DIY Transmitter
Post by: v2 eagle on May 10, 2016, 01:54:58 AM
the range is dependant on the module and not on the radio. so if your module doesnt has any manuf defect then it shoudld be fine.
Title: Re: DIY Transmitter
Post by: v2 eagle on May 10, 2016, 01:55:56 AM
600 is a good offer. the gimbals, switch and the box is worth enough, you can threw away the mb and display.
Title: Re: DIY Transmitter
Post by: v2 eagle on May 10, 2016, 02:02:49 AM
http://www.rcgroups.com/forums/showthread.php?t=2406337

an ongoing thread !!
Title: Re: DIY Transmitter
Post by: Dipanjan on May 10, 2016, 09:46:41 AM
Quote from: v2 eagle on May 10, 2016, 01:54:58 AM
the range is dependant on the module and not on the radio. so if your module doesnt has any manuf defect then it shoudld be fine.
Yes, I am aware that the range depends on the module, but the module does have some limitations, right? So, I was curious to know what range to expect from from a Orange Tx module? Do you have idea.
I have seen the post you linked to rcgroups.
Thanks for your time. Much appreciated.
Title: Re: DIY Transmitter
Post by: v2 eagle on May 10, 2016, 07:37:14 PM
at least 800m is expected even at worst case. and i do not see any LOS need more than 400m!.
Title: Re: DIY Transmitter
Post by: v2 eagle on May 10, 2016, 07:37:54 PM
if in so doubt, why dont you apt for frsky module, same cost and proven reliablity.
Title: Re: DIY Transmitter
Post by: girishsarwal on May 11, 2016, 09:17:05 AM
Use a frsky diy module and program the arduino to generate a ppm. Will save you some harrowing experience. Get the frsky taranis gimbals if you strive for higher quality. Improtant to shield the wires and contacts while soldering to ensure no signal interference or you might see the adc jumping

Title: Re: DIY Transmitter
Post by: Voice of deaf on May 12, 2016, 03:54:06 PM
Skip the op amp part for pots