As I've mentioned in a couple of other threads, I'm building a custom RC transmitter for the purposes of trying to "realistically" simulate the engine orders given from the bridge crew to the engine room via a simulated engine telegraph. In addition, we're trying to simulate the realistic delays in engine changes. Our application for this is specifically a 1:125 scale Lindberg "Blue Devil" Fetcher class DDS model. The transmitter will have adjustable engine speed scales that will allow it to be adapted and fine-tuned for the desired simulation of the desired ship.

The How:
Engine orders will be given to the transmitter via 5" sliders (one for the port engine, one for the starboard engine) that are read by an Arduino Microcontroller. The user will not be controlling the transmitter directly. The microcontroller will be managing engine throttles at all times. The sliders will be divided in [STRIKE]6 [/STRIKE 8]ranges that correspond to:
Ahead Flank
Ahead Full
Ahead 2/3 (added 1/15/2013)
Ahead 1/2 (added 1/15/2013)
Ahead 1/3
Stop
Back 1/3
Back Full

Let's say the port engine is currently at "Ahead Full", which equates to 90% throttle. If we suddenly order "Back Full" by pushing the slider to the bottom extreme, the microcontroller will slowly reduce throttle over time until it gets to zero. Once it hits zero, it will begin reversing the throttle slowly until 75% reverse throttle is achieved.

The transmitter will have a 16x2 character LCD display that will display a number of different screens. But the primary purpose is to display the current port and starboard engine orders. When a new order is given, the appropriate order is shown on the LCD screen and the order begins blinking. Meanwhile, the microcontroller is adjusting the throttle behind the scenes to "reach" the new engine order. When the throttle reaches the commanded order, the order stops blinking on the LCD.

How does the microcontroller control the throttles? The microcontroller will use integrated chips (IC's) called "digital potentiometers" that will replace the potentiometers and sticks from a hacked conventional transmitter. This allows the Arduino to control the inputs to the transmitter digitally. I plan to use dual-channel 256 step digital 10k pots, meaning I can independently control 2 digital potentiometer outputs from 1 chip vi the microcontroller. I can control additional channels simply by adding additional chips. Note that these chips also come in single-channel, quad-channel, and 6-channel. I have selected the Maxim DS1803 dual 10k pot i2c bus chips for this.

UPDATE: 4/7/2014: Last month the circuit board from the HobbyKing transmitter failed for unknown reasons. Rather than order and hack another transmitter, I discovered that I could drive the separate 2.4Ghz radio module directly. This module has 4 wires going to it: +5V, GND, transmit signal, and PPM. The transmit signal must be supplied with +5V in order for the radio module to transmit. You can use it like an on/off switch. The PPM pin is connected to a digital I/O pin on the Arduino. The Arduino generates the PPM frame using some code that I found from another user here on rcgroups.

Sound
The transmitter will also have an MP3 player and speaker that is controlled by the micorcontroller. When a new engine order is given, you will actually "hear" the engine telegraph bells sounding for a second or two. Then you will hear a voice relay the engine order response from the engine room telegraph. And when the engine throttle reaches the ordered speed, you will hear a voice confirm this. Note that all these sounds will come from the transmitter, NOT the ship!

Steerage
We are also going to try to accurately simulate the ship's wheel. The transmitter box will have a small ship's wheel on it that will be connected to a rotary encoder. This essentially means the wheel can be spinned continously. Again, the user will not be controlling the rudder directly. For full rudder deflection to port, or example, it may require 5-10 full turns on the ship's wheel (or whatever we figure out is realistic). This means it takes time to turn the ship's rudders. The rudder position will be displayed on the LCD screen. I might also use a circular LED graph as a visual aid but haven't decided on this yet.

How do I get out of trouble?
Attempting realistic simulation is all find and dandy, but what if I have to rev the engines to full and get full rudder deflection instantly to get the model out of a bad situation? There will be a toggle button on the transmitter that switches it from "simulated" mode to "instant" mode. In "instant" mode, the sliders become direct-throttle controls with no delay. The rudder now only requires 1/2 turn in either direction for full rudder deflection.

Why not just use a programmable transmitter?
Well we could, but where would the fun in that be? Also programmable transmitters add to the cost. It's cheaper and probably easier for me to just hack a low-cost transmitter.

Why not use specialized ESC's for slow engine throttle?
Because it's not just about engine delays. We want to simulate actual engine orders as given by the bridge crew, and we want visual and audio feedback to these orders. Simply using specialized ESC's wouldn't accomplish this.

Other factors
We also wanted the ship itself to work with a regular transmitter if we need it to without any changes. For this reason, we could switch off our customer transmitter and switch on a regular unmodified transmitter and still operate the ship (assuming of course that it is properly paired with the receiver).

Parts List (updated as of 2/4/2013):
Transmitter:

• HobbyKing Mode-2 6CH TX/RX (HK-T6A-M2) (Update 4/7/2014: Only the 2.4Ghz radio module is now used)
• Arduino Uno R3 microcontroller
• (2) DS1844 10k quad 64-step digital potentiometers (for 2 RGB LED's)
• Newhaven serial 16x2 LCD blue w/ white text
• (2) 100MM 10K OHM slide pots (logarithmic or linear)
• (2) 5MM RGB LED's for real-time engine-throttle status
• 24-step Rotary encoder with 6mm shaft
• 9.6" x 6.5" x 3.2" ABS plastic enclosure
• (7) panel mount momentary push buttons
• (2) small toggle switches
• DPDT switch for power to microcontroller and power to transmitter guts
• 8 or 16 AA batteries
• Adafruit Stereo audio amp http://www.adafruit.com/products/1712
• MP3 player with TTL/Serial interface and SD card reader (from http://www.mdfly.com)
• 3" 4Ohm speaker

Ship:

• (2) Turnigy TrackStar 18A 1/18th Scale Brushless Car ESC (Remove 2/15/2013)
• (2) Hobbyking Donkey ST380L-3000kv Brushless Inrunner (Remove 2/15/2013)
• (2) 47:1 Metal Gearmotor 25Dx52L mm HP from Pololu.com (added 2/15/2013)
• (2) Mtroniks MicroViper Marine 10 speed controller (added 2/15/2013)
• Turnigy 2200mAh 3S 25C Lipo Pack
• Turnigy Accucel-6 50W 6A Balancer/Charger
• Dumas drive shafts & stuffing boxes
• Dumas brass props
• 4mm to 3mm universal joint couplings

Update 12/29/2013:
I created a Windows proof-of-concept simulation of the transmitter to show how the engine orders will work. It's written in C# and requires the .NET 4.0 framework. You can try this out for yourself if you'd like: http://www.hauntsoft.com/transmitter.zip

Update 1/3/2013:
I have written about 300 lines of code for the Arduino so far and have the slide pots being read and the engine orders being processed and displayed on the LCD screen:

Custom ship TX: Reading analog sliders (1 min 56 sec)

Next step is to test the digital potentiometer chips with some LED's to show engine throttle output.

This sounds really cool. I'm looking forward to how this turns out. Here is a pic of the mod I did to my Futaba 6EX. Thread is here-

https://www.rcgroups.com/forums/show...1015913&page=7

Originally Posted by xx29l9

This sounds really cool. I'm looking forward to how this turns out. Here is a pic of the mod I did to my Futaba 6EX.

That's pretty cool. I like what you did with the pots on the left side.

I've added 4 tactile buttons and started implementing a simple menu system for the LCD display. The buttons will be labeled up,down,left,right. I might add a 5th button which would be a select button. When not in the menus, the LCD can be cycled through 3 "info" displays currently using the left and right buttons. In normal mode, the engine orders and the rudder position are displayed on the LCD. In "throttle" mode, the throttle % for each engine is displayed, and in "analog" mode, a value between 0 and 1023 is displayed for each of the sliders to show you the actual position of the sliders (for debugging purposes). I'll probably add more info screens as I think of them.

To access the menus, you press either the up or down buttons. So far I've only created 2 menus: Set Backlight and Set Contrast. These of course allow you to adjust the backlight brightness and the display contrast of the LCD. I should also mention that all of the settings in the menus will be saved to EEPROM whenever they are changed so that the transmitter remembers them when you next power on the transmitter -- even if the batteries have been removed.

No video yet for this update. I will probably wait until the next update when there's more to show.

I did some more work on the ship transmitter and have a new video to show. The microcontroller is now hooked up to a dual digital potentiometer chip, and I have 2 LED's hooked up to the outputs of that chip as a test. I used the DS1803 chip which is an i2c bus, 10k 256-step dual digital pot. The night before last I tried using 2 SPI-based digital pots and I just could not get them to work. I like the i2c bus much better because I can run up to 8 devices off just 2 analog outputs from the microcontroller. It's good to have plenty of free digital I/O ports for other purposes. Also I can expand the digital I/O just by adding another i2c chip. Anyway, as the microcontroller is changing the engine throttles, you'll see the LED's slowly brighten and dim. 30% brightness = stop, 100% brightness = ahead flank, 0% brightness = full reverse. The output going to those LED's (1 for left engine, 1 for right engine) is what will actually be driving the real transmitter. I can literally replace each LED with 3 wires going directly to the transmitter for whichever channel I want to control. The existing physical pots would be disconnected and these 3 wries would connect to those wires. Also at the end of the video I cycle through the different display modes (as they exist currently) and I show you the LCD contrast and LCD backlight menus.

The next step will be for me to charge up the battery and hook up the receiver, ESC's, and motors and test the unmodified HobbyKing transmitter with the motors to make sure that all works. I'll put a piece of masking tape on the shafts so I can see them spin. After that, I could potentially begin taking apart the HobbyKing transmitter and wiring it up to the microcontroller and have it run the motors for real. I also still need to order a rotary encoder for steerage.

Custom ship rc transmitter update 1/9 (2 min 40 sec)

Not sure where it is located there is a Master's school back East (New Hampshire maybe) where skippers pilot scale models of the ships they will captain later on (full scale). One of the things that they have is a delay in the response to engine orders and on the larger models, rudder commands. My dad went to the Navy equivalent of this school and he said it really helped with the San Jose (a Mars class fast replenishment ship, which had one screw (steam plant) and no bow thruster along with an enormous amount of topside windage due to her replenishment rigs.

Sorry for the unusually dark & blurry video this time around.

I added a 24-step rotary encoder that will eventually take a ship's steering wheel and added the code to process the rotary encoder. The goal is to require the wheel to be turned multiple full turns (720 degrees) in order to get full rudder deflection (of about 30 degrees each way) as on a real ship. Also added an option to set the maximum deflection of the rudder in degrees. Will be adding an option to scale the resolution of the wheel up and and down so that the transmitter can mimic any ship or boat. Video also shows some of the other adjustments:
ENGINE CHANGE SPEED (how quickly the throttle moves)
ENGINE ORDER DELAY (number of seconds before order is acted on)
REVERSING DELAY (number of seconds to pause before switching motor direction)

Custom RC ship transmitter Update 1/15/2013 (1 min 20 sec)

I'll be hacking the HobbyKing transmitter soon... I'm still waiting for the correct size bullet style connectors and XJ60 connections to be able to hook up the motors to the ESC's and the battery.

We also added 1/2 Ahead and 2/3 Ahead engine orders.

This is a test of one of the RGB LED lights that I got. I hooked up the green and the blue components to a DS1803 dual digital potentiometer and hooked up the red component to one of the Arduino's digital I/O pins. This was just a test to see how it works. I added some code to make the LED follow what the port engine throttle is doing. When the engine is at stop, the light is red. When the engine throttle is forward, the light is green, and the brightness represents the engine throttle %. When the engine is in reverse, the light is blue, and again the brightness represents the engine throttle %.

Custom ship rc transmitter update 1/20/2013 (0 min 42 sec)

I've ordered 2 DS1844 chips which are quad (4) digital 64-step potentiometers on a single chip. I'll use one for the left LED and one for the right LED. I may use the left over digital pot from each chip for something else. I still intend to use the dual 256-step chips for the actual throttles and for the rudder.

One further note... The engine status LED's will be flashing when an order is being processed and the target engine speed has not yet been reached. This has already been coded, but I decided to turn it off for this video as made the changes in brightness easier to see.

So who's actually following this thread? Just curious!

Originally Posted by Skystream

Ttest So who's actually following this thread? Just curious!

OBW

I am too. It's well over my head, but I'm admiring the effort being put forth, and hope this encourages growth to the hobby.

Cool, as long as there are at least a couple of people interested, I'll keep posting updates. Here's the update for today:

I've added the RGB indicator lights for both engines, but I'm using dual digital pots to control the green and blue on each light and I'm using a digital I/O pin to turn the red component on & off. I'll be replacing these 2 dual chips with 2 quad 64-step chips. What this means is I'll be able to completely control the red, green, and blue components of each light with 64 levels of brightness for each component, and have an extra digital pot left over from each chip. I may use the extra digital pots on the extra channels of the transmitter for things like turret servos, signal lights, or whatever.

My dad asked that the indicator lights blink while an engine order is being acted on but not yet complete. I also decided to have the lights alternate between green/red or blue/red when the engine order is for the engine to be stopped. It flashes between green/red when the engine is being stopped from a forward throttle, and it flashes between blue/red when the engine is being stopped from a reverse throttle. So the indicators are as follows:

solid red = engine stop
blinking red = engine stopped, new order being processed
blinking green = engine is forward throttle, moving to new ordered speed
solid green = engine is at ordered forward throttle
blinking blue = engine is reverse throttle, moving to new ordered speed
solid blue = engine is at ordered reverse throttle
red/green = engine has been ordered to stop from a forward speed
red/blue = engine has been ordered to stop from a reverse speed

Custom ship rc transmitter update 1/21/2013 (3 min 0 sec)

I'm following you, Skystream. Don't quit now.

Pete

Originally Posted by pops52

I am too. It's well over my head, but I'm admiring the effort being put forth, and hope this encourages growth to the hobby.

I've got to get this book.

Originally Posted by Skystream

This is a test of one of the RGB LED lights that I got. I hooked up the green and the blue components to a DS1803 dual digital potentiometer and hooked up the red component to one of the Arduino's digital I/O pins. This was just a test to see how it works. I added some code to make the LED follow what the port engine throttle is doing. When the engine is at stop, the light is red. When the engine throttle is forward, the light is green, and the brightness represents the engine throttle %. When the engine is in reverse, the light is blue, and again the brightness represents the engine throttle %.

http://www.youtube.com/watch?v=vuq40yO_484

I've ordered 2 DS1844 chips which are quad (4) digital 64-step potentiometers on a single chip. I'll use one for the left LED and one for the right LED. I may use the left over digital pot from each chip for something else. I still intend to use the dual 256-step chips for the actual throttles and for the rudder.

One further note... The engine status LED's will be flashing when an order is being processed and the target engine speed has not yet been reached. This has already been coded, but I decided to turn it off for this video as made the changes in brightness easier to see.

So who's actually following this thread? Just curious!

Absolutely following it mate, this is the way forward!

Originally Posted by fooman2008

Not sure where it is located there is a Master's school back East (New Hampshire maybe) where skippers pilot scale models of the ships they will captain later on (full scale). One of the things that they have is a delay in the response to engine orders and on the larger models, rudder commands. My dad went to the Navy equivalent of this school and he said it really helped with the San Jose (a Mars class fast replenishment ship, which had one screw (steam plant) and no bow thruster along with an enormous amount of topside windage due to her replenishment rigs.

Port Revel in France seems to be the most well-known of the manned model pilotage schools?