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FLYSKY GT3b Transmitter

Old 03-10-2011, 05:35 PM
  #796  
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So can I use this 2.4G module for Futaba 3PK and how to do it if yes? Thanks.
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Old 03-10-2011, 05:43 PM
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Originally Posted by psx
OK, I will try to explain it. There is microprocessor inside this transmitter. It is microprocessor from company STMicroelectronics and its type is STM8S105K4T6C . This processor can be programmed In-Circuit and only 4 wires are needed to do it, 2 of them are GND and 5V , next 2 are RST (reset) and SWIM (programming/debug pin).
And this radio is quite simple, except next chip (lcd driver HOLTEK HT1621B) and 2.4G module (same module is in another transmitter FS-TH9X), it contains only some resistors, transistors and switches.

As connecting/not connecting to switch. This is what I checked, that one pin on 78M05 (regulator) is connected with this 5V pin/hole. And if it was directly connected to battery, there will be no 5V, but full battery voltage.
I looked at images of PCB yesterday and it looks like LED+ is connected to 5V by some resistor and it is possible, that LED- is connected to transistor which microprocessor uses to switch LED on. If it is like this, all that is needed to set LED permanently ON is connect LED- to GND. I cannot check it now, I am for several days outside of home.

To reprogramming. I am sure it can be reprogrammed. Correct programming interface is needed, for this microprocessor it is ST-LINK from STMicroelectronics. I don't have it, I did previously only with microprocessor from another company (Atmel AVR).
But maybe I will order STM8-Discovery kit, which contains that ST-LINK and demo board with similar microprocessor as is in GT3B transmitter. And than try to read program code from GT3B if it is not locked (maker can set this microprocessor to not be able to read program code from it).
So there can be 2 possibilities:
- code can be read and than somehow changed
- code cannot be read, than there will only be possible to write whole code from scratch
If im correct Rlink-STD should also be able to read the flash program and move past the lock if it is present.
Ive just ordered some spare chips to play with, when they arrive we shall see if we can remove the program from it. If not maybe the company could send us the hex file to modify it so it works properly.
I also wonder what the gt3 uses and if its the same chip with the proper code. kinda alot of work for a 35 dollar radio, but it would be neat if it could work.
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Old 03-10-2011, 11:38 PM
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It may be a little bit of work for a $35 radio, but youre improving its performance. Its already a good and cheap radio which workss well, but with a lttle bit of effort, it can be as good as any other big radio brand.

Please do let us know if you can reprogram it.
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Old 03-10-2011, 11:49 PM
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GT3B


GT3


Welll lookie here. The daughter boards are both the same. The GT3 module has the daughter board with the same manufacture date as my GT3B radio board.
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Old 03-11-2011, 02:42 PM
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Originally Posted by QuangVuong
GT3B
Welll lookie here. The daughter boards are both the same. The GT3 module has the daughter board with the same manufacture date as my GT3B radio board.
It isn't picture of GT3, but FS-TH9X (8-channel aircraft/heli radio). But if GT3 is compatible, I think there will be the same module.
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Old 03-12-2011, 05:53 AM
  #801  
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Originally Posted by turbobuick6
If im correct Rlink-STD should also be able to read the flash program and move past the lock if it is present.
Yes You can use Rlink-STD, because it supports SWIM mode to program STM8 microcontrollers.
Ive just ordered some spare chips to play with, when they arrive we shall see if we can remove the program from it. If not maybe the company could send us the hex file to modify it so it works properly.
I have big good news. Today I read content of flash (program memory) and eeprom (data memory). It wasn't locked. So it is possible to do anything now.

It is possible to modify original firmware (after some understanding of it) and also write completly new one (as it was done for FlySky TH9X radio).
And it is always possible to return back to original firmware.

Also I think that the 2.4G module inside is capable of 8 channels because it can do 8 channels in FS-TH9X. Don't know if it can be usable for cars :-)
kinda alot of work for a 35 dollar radio, but it would be neat if it could work.
Peoples are doing it because it it so cheap radio :-) Look what was done for that FlySky TH9X $50 dollar radio. There are at least 4 alternative firmwares possible to run at it (er9x, th9x, gruvin9x, radioclone). All are opensource and You can modify it as You want.
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Old 03-12-2011, 06:29 AM
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Originally Posted by QuangVuong
The GT3B isn't a modular radio. You can use the module from the older GT3. A couple pages back, there is a post by reptile, who put a GT3 module into his KO Propo radio.
Any idea if that module will fit a KO Propo EX10 Helios? Is it a direct fit?
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Old 03-12-2011, 07:47 AM
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I think someone uses that exact combo with good results... i would therefore suspect it works...

Not 100% sure but like 95...
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Old 03-12-2011, 10:43 AM
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Originally Posted by vones325
So can I use this 2.4G module for Futaba 3PK and how to do it if yes? Thanks.
I think You can use it. The module requires only GND, 5V and PPM signal. And if You want BIND button also, connect it between pin SW and GND.

I measured PPM generated by GT3B by oscilloscope and its level is 0V and about 3.3V (long 3.3V pulses and about 300us 0V spaces). When measured by voltmetter, it was about 3V.

So maybe Futaba is generating not compatible signal (inverted, another voltage, ...) and will need some circuit to make it compatible. If You can, measure that PPM signal with oscilloscope.
But maybe this, what I found at rcgroups, will be enought:
"The 3PK will output PPM data with or without a module. To see any data though you'll need a pullup resistor on the PPM output when you don't have a module installed. I'd recommend 5 volts with a 10K resistor. "
So it looks like 3PK has PPM output done with open-collector and needs resistor to 5V voltage to see some signal.
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Old 03-12-2011, 01:06 PM
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Originally Posted by psx
Yes You can use Rlink-STD, because it supports SWIM mode to program STM8 microcontrollers.

I have big good news. Today I read content of flash (program memory) and eeprom (data memory). It wasn't locked. So it is possible to do anything now.

It is possible to modify original firmware (after some understanding of it) and also write completly new one (as it was done for FlySky TH9X radio).
And it is always possible to return back to original firmware.

Also I think that the 2.4G module inside is capable of 8 channels because it can do 8 channels in FS-TH9X. Don't know if it can be usable for cars :-)

Peoples are doing it because it it so cheap radio :-) Look what was done for that FlySky TH9X $50 dollar radio. There are at least 4 alternative firmwares possible to run at it (er9x, th9x, gruvin9x, radioclone). All are opensource and You can modify it as You want.
Wow this is very good news. What programmer did you read it with? And do you think you can upload the flash memory and EEPROM files here. Put them both into a zip file and upload it if you can. Thanks
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Old 03-12-2011, 01:09 PM
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maybe write a how to on changing the FW that's slightly more involved then i (at least) have previously done...
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Old 03-12-2011, 02:05 PM
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Originally Posted by QuangVuong
Wow this is very good news. What programmer did you read it with?
I bought kit STM8S-Discovery, because it was cheapest possibility to get programmer. Overview and where to buy it can be find here:http://www.st.com/internet/evalboard/product/247087.jsp
It contains ST-LINK programmer and also development board with similar microcontroller as is in GT3B. It is connected together and You can develop programs at this development board.

When You want to program external device (as GT3B), it is needed to desolder 2 points at the ST-LINK board and then connect 4pins from ST-LINK to GT3B.
They are both at the same order. I didn't solder it to GT3B, but used spring-loaded pins to temporary connect it to GT3B. I can post some photos if You want.

Programmer is also from STmicroelectronics, it is in "ST Toolset" from: http://www.st.com/stonline/stappl/re...T&FamilyID=141

In STVP (ST VIsual Programmer) I selected Hardware:ST-LINK , Port:USB , Programming_mode: SWIM and Device:STM8S105x6 . And than it worked.
Only one issue was that at my processor is label STM8S105K4T6C, which is 16KB device, but I have found that it has 32KB of flash, so it should be STM8S105K6T6C. About 27KB is used.

And of course, it is possible to use another programmer, which support SWIM interface to program microcontrollers STM8.

And do you think you can upload the flash memory and EEPROM files here.Put them both into a zip file and upload it if you can. Thanks
I would prefer to send it by email. It is to prevent me to be sued if I put it to public on the web.
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Old 03-12-2011, 02:30 PM
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I for one would love pictures, more details are better...

Now not sure if this can be done but i think if you do decide to write code i was hoping you would "take requests" i mean the 3rd channel as a 3 way would for instance be "epic awesome" i mean if we're going to crack op en the case and tinker with the core programming we might as well put in a 3 way switch right

Also more out of idle curiosity what language did they code the transmitter in? Assembly?
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Old 03-12-2011, 05:46 PM
  #809  
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Originally Posted by psx
I think You can use it. The module requires only GND, 5V and PPM signal. And if You want BIND button also, connect it between pin SW and GND.

I measured PPM generated by GT3B by oscilloscope and its level is 0V and about 3.3V (long 3.3V pulses and about 300us 0V spaces). When measured by voltmetter, it was about 3V.

So maybe Futaba is generating not compatible signal (inverted, another voltage, ...) and will need some circuit to make it compatible. If You can, measure that PPM signal with oscilloscope.
But maybe this, what I found at rcgroups, will be enought:
"The 3PK will output PPM data with or without a module. To see any data though you'll need a pullup resistor on the PPM output when you don't have a module installed. I'd recommend 5 volts with a 10K resistor. "
So it looks like 3PK has PPM output done with open-collector and needs resistor to 5V voltage to see some signal.
Do you mean I use the +5V, GND and PPM pin on the GT3B 2.4G PCB which can connect to corresponding output pin (pin1:PPM, pin2:+6V lowered to 5V and pin4:GND) of Futaba 3PK transmitter? Thanks.
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Old 03-12-2011, 05:55 PM
  #810  
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PPM, +5V and GND from GT3B 2.4G PCB
Attached Thumbnails FLYSKY GT3b Transmitter-dsc01211-mod.jpg  
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