HL 27mhz radio protocol

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Cesco
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HL 27mhz radio protocol

Post by Cesco »

New owner of a HL Tiger 1.

I am intrested in substituting the 27mhz radio for a 2.4G one. But the HL radio is not what i am used to from normal RC gear. The protocol is completely different. I did hook up my oscilloscope and made some pictures. Seems like a manchester coded bitstream. Really? Anything known about this?

Image
Last edited by Cesco on Sat Apr 11, 2015 9:46 pm, edited 1 time in total.
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wibblywobbly
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Re: HL 27mhz radio protocol

Post by wibblywobbly »

Don't ask me about the technical aspects but I think I am correct in saying that your analysis is correct. HL use a split channel system, it's some devious system whereby they split the signal and only use half of it, and is why their radio gear is totally incompatible with anyone else's, either the old crystal tx's or the 2.4ghz (which is still the same RX18 as the old gear, so it needs the same pulse frequency modulation if that's the right term).

RobG
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Tankbear
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Re: HL 27mhz radio protocol

Post by Tankbear »

Hello Cesco,

This question has come up a few times over the years on different forums. And from what I recall it has never really been figured out. But I think your looking at it the wrong way, your trying to figure out the FM code between the radio & receiver. You should be thinking about the communication between the HL FM receiver and the RX18, and this is achievable as there is already some products on the market which does this (IP4HL, RC5HL, DBC2). This methods allows you to use a standard 2.4ghz radio & receiver then converts the servo commands into something the RX18 can understand.

Ian.
www.mad-tanks.weebly.com
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Cesco
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Re: HL 27mhz radio protocol

Post by Cesco »

Hi Tankbear,

I am tapping the data that goes into the fm modulator, which is the same that goes into the rx18.

>IP4HL, RC5HL, DBC2
Exactly what i was looking for. Unluckily nothing open source?

I did drive the tank a little and there are some quirks. Forward is smooth, reverse is much more sensible and jerky?
The stupid gear-wearing recoil simulation can not be switched off?
Turning while going forward is slow, then suddently goes into a spin?
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Re: HL 27mhz radio protocol

Post by Cesco »

I think i got most of the protocol sorted out.
A message consists of a 1ms high pulse for sync, then 31 data pulses.
Data pulses are a 0 when the signal changes in 0.6ms and 1 if signal doesent change in 0.6ms.

Those data pulses are NRZ encoded. Decoded we get 31 bits total consisting of:
11111100 no idea, doesent change
01111 forward-reverse value, 15=middle
00000 k-buttot, tur-right, tur-left, down, up
011111 left-right value, 16=middle
00 motor-button, g-button
0000 checksum
00 no idea, doesent change

I got an arduino firmware to decode the stuff and display it on PC, and i will soon have an arduino sketch to encode that stuff. If it works it should be simple to add a normal RC pwm reading routine, single channels or ppmsum, sbus, speksat, ibus, sumd. This would allow to do RC to HL protocol conversion with a $3 arduino mini and some connectors.

It would also allow to run both motors on separate esc's, or to have the turret gyro controlled.
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Re: HL 27mhz radio protocol

Post by Cesco »

Seems to work :)
https://www.youtube.com/watch?v=Fs7ea9h ... e=youtu.be

Source:
This is GPL licence. http://en.wikipedia.org/wiki/GNU_General_Public_License
Here's the code used in the video: https://github.com/Cesco1/ArduHL

Output to rx18 is pin 11, input from RC is pin2 ppm-sum. Note the arduino runs on 5V but the rx18 provides 8V.
This firmware runs on any 328 based arduino. Supports onlx ppmsum, motor button and motor controls. Additional stuff will be implemented whenever i feel like it.

Now i wonder if i should bypass the rx18 pwm for the motors and let the arduino do this. I would still use the rx18 motor drive electronic, i dont got any esc's here. Soldering required :(

Rx18 pwm uses 32 steps for motor control. That is 15 froward + 15 reverse. The arduino + conventional RC receiver can easily do 256 steps. This would result in much finer control. And i could make my own mixer, avoiding the rx18 shortcomings like recoil jump or spinning.

The arduino is also capable of 2 additional servo outputs. This could be used for better turret control.
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Tankbear
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Re: HL 27mhz radio protocol

Post by Tankbear »

Excellent work Cesco :clap: :clap: :clap:

Given the option to use your own esc for the tracks, I say go for it. Like you say it gets rid of the track recoil and superspin but given a little bit of time you could maybe program in some inertia/momentum or something else to make it more realistic.

Your the man :thumbup:

Ian.
www.mad-tanks.weebly.com
www.rctankelectronics.com
www.rc-truck.weebly.com
www.rc-boat.weebly.com
Cesco
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Re: HL 27mhz radio protocol

Post by Cesco »

Ty Tankbear.

Unluckily using the onboard esc's needs a lot of wire soldering from arduino to inside the rx18.
I wonder if there is a simpler way to get rid of that track recoil thing. The spinning thing is manageable, i just have to remember to always apply full forward stick during turns.

Test run with orangerx satelite and Devo transmitter. Runs a lot better than with the stock transmiter.
https://youtu.be/PMbZBepDin4

I disassembeld the shooting thing to have a look at. There was a sideways 2mm hole in the barrel, probably to weaken the shots. Tapped that. After reassembly it wont stop firing. I messed up this switch somewhere ...
Phantom0589
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Re: HL 27mhz radio protocol

Post by Phantom0589 »

Hello dears! I want to make your tank rx18 on the arduino nano. There is this article on the website https://www.rcgroups.com/forums/showthr ... th-arduino. While https://github.com/Cesco1/ArduHL - page not found. The code is missing files (Missing files:
wdt.h
arduino.h
and the compiler in the Arduino IDE, it throws an error:
the compilation has terminated.
output status 1
avr / wdt.h: there is no such file or directory) to me one user on rcgroups - answered. That I should buy an arduino nano Board, go to College to study programming. And here in General it if this code is open and there is a GPL license. For example DIY Multiprotocol - also with the GPL license create, change as you want. ...
Help dear friends)Yes,I want to make arduino and rx 18. Not otherwise. Know simple servo and us to use.
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