Joystick model remote control with iRangeX multiprotocol module and Android smart device – even more compact!

The previous blog described how the originally used remote control transmitter can be replaced by an iRangeX multi-protocol module and how the entire setup can be simplified.

In this blog, an even more compact structure is described in which the USB hub, the USB2PPM PiKoder and the multi-protocol module are mechanically combined into one unit, which then only needs to be connected to the smart device and the joystick.

The following steps are required for the implementation:

1. Extend the USB hub cable
2. Modify USB2PPM PiKoder with USB connector
3. Realize mechanical rack
4. Assemble and wire modules

Extend the USB hub cable

The common USB OTG hubs (on the go) usually have a very short connection cable (0.1 – 0.15 m). In practical use, this results in restrictions, since the hub must always be close to the smart device and possibly hangs in the air next to the holder and so a “rigid connection” with the PiKoder is not possible.

The extension of the connection cable is not a problem. It is only to be noted that an OTG connector with the corresponding coding (see picture) is still used as the connector, because otherwise the hub will not be recognized and will not be supplied with voltage.

The easiest way to extend the extension is to solder a piece of USB cable of the desired length to the hub board and attach the existing plug with the short cable end to the other end and fix it with shrink tubing.

Modify USB2PPM PiKoder with USB connector

For the direct connection between the USB hub and the PiKoder, the USB2PPM requires a USB plug (see picture on the right) instead of the normal USB micro socket. So that the connector can be installed, saw the circuit board in order to then be able to push through the fastening straps. In addition, a hole is required in order to be able to wire the connection cables of the plug (see picture below).

Then stick the connector to the circuit board with two-component adhesive and equip the circuit board with the remaining components (see pictures below). Note: In the further course of the project I replaced the three-pin header with a Molex connector.

Finally connect the pins of the USB connector with the corresponding PiKoder pins; a thin, insulated wire is used for this. The following pictures show the schematic connection and then you can see the actual wiring on the underside of the circuit board.

Realize mechanical rack

The subrack consists of a simple angled wooden structure. The square base plate with a side length of 85 mm accommodates the hub and the USB2PPM Pikoder. The multi-protocol module is clamped in the vertical fork. To improve the appearance of the cable routing, I drilled a corresponding channel.

Assemble and wire modules

You can see the complete setup in the following pictures. The hub is fixed with double-sided adhesive tape, the USB2PPM PiKoder is plugged in and fixed with screws through the two front mounting holes. It is best to use some washers as spacers so that the circuit board does not bend.

With the micro USB connector, the “compact transmitter” is initially intended for connection to an Android device. With a small adapter, e.g. from Micro USB to USB C plug, the transmitter can of course be easily connected to a Surface Notebook.

Joystick model remote control with multi-protocol TX module iRangeX IRX4 +

In the two previous articles on model remote control with joystick, a “completely normal” remote control transmitter was used to transmit commands. The control sticks and various switches of the transmitter were not needed because the control itself is done by the joystick.

The overall structure can therefore be simplified by using a multi-protocol TX module such as the iRangeX iRX4 + instead of the complete remote control transmitter.

The module can – just like the remote control transmitter – be controlled directly via the PPM signal from the USB2PPM – PiKoder. Since the iRangeX already operates with an operating voltage of 5 volts, the power supply is also provided via the USB2PPM PiKoder and no additional battery is required.

Setup

The USB2PPM PiKoder is set up according to the instructions. Even if you have only equipped one cynch socket so far, the three-pin header can be retrofitted without any problems.

The connection between the iRX4 + module is made via a three-wire cable (Vcc, PPM and Gnd) (see picture below left). At one end of the cable there is a three-pin socket for plugging into the corresponding pin header of the USB2PPM, on the other side the five sockets of the module are adapted – you can see the pin assignment that the module expects in the picture on the right.

No further adjustments or changes are required.

And the structure described here can of course also be used in connection with a Windows notebook.

Joystick model remote control with Spektrum DXe (2)

The first entry in this series used a notebook to translate the joystick inputs into commands for the USB2PPM. Alternatively, an Android (TM) smart device with a corresponding app can be used for selected joysticks.

The hardware structure in the title picture is the same as the configuration in the Part 1 Except for the computer, which is replaced by the smart device, and the hub: a USB OTG hub must be used in conjunction with the smart device.

With regard to the preparation of the remote control transmitter, the same considerations for ergonomics apply and it is advisable to expand the remote control with a switch as described in Part 1.

With regard to the app itself, you can choose between the free app Joystick2PPM and a special app for quadrocopters Joystick4UAV (see below); you can find both apps in the Google Play Store.

Joystick2PPM (Android App)

The user interface of the app largely corresponds to the Windows implementation and is intuitive and easy to understand. The joystick controls are on the left and the servo channels are mapped to the right with drop-down boxes.

The joystick and the USB2PPM are automatically recognized after starting the APP. When using the application for the first time, the user must enable access to the corresponding USB interfaces.

Please note that the app currently only supports a limited number of joysticks and other operating devices. The current list of the compatible devices can be found in the Playstore at any time.

Joystick4UAV (Android App)

The Joystick4UAV app is an advanced version of the Joystick2PPM application, which is geared towards the needs of remote control of quadrocopters or other vehicles (UGV) and boats (USV) with a flight controller.

The basic structure of the Joystick4UAV corresponds to the apps already described. The four joystick axes are mapped to the remote control channels 1-4 according to the usual assignment for flight controllers. You can of course adapt this assignment within the four channels according to your preferences. All channels can be inverted by checking the associated box.

The flight mode is coded in channel 5. There are six modes available. The flight mode selection takes place by pushing the joystick buttons 7-12 (see figure below right), where button 7 sets flight mode “1” and button 12 sets flight mode “6”. The selected flight mode is displayed numerically (“1” in the picture above) and the bar corresponds to the transmitted channel value.

The remaining buttons 1-6 (button B1 .. B6 in the upper area) and the hat switch are available for special functions and can be assigned to channels 6-8 as required. If the box belonging to the channel is activated, the button behaves as a switch.

Please note that only the Logitech Extreme 3D Pro joystick is currently supported in the app.

Tester for Metz MECATRONIC RC servo 190/18

I am currently working on the restoration of a Metz MECATRON ‘BABY’ radio remote control. For testing and commissioning the rowing machine, I didn’t want to switch on the entire remote control every time, so I built a simple tester.

This tester reproduces the output of the receiver 191/S – a relay with a switching contact – with a corresponding button. Thus, the function of the rowing machine, which depends on the control panel used, can then be tested.

In my case, the control panel 1 is inserted; the following switch rhythm is realized according to the user manual:

Transmitter key pressed: Rudder left as long as button remains pressed
Press the transmitter button briefly (approx. 0.4 seconds), release briefly (approx. 0.4 seconds) and hold down: Rudder on the right, as long as the button is pressed the second time.
After letting go of the transmitter button, the rudder always goes neutral by itself.

In the setup presented here, of course, the transmitter button corresponds to the button.

The tester can be easily mounted on a laboratory circuit board and the wiring effort is minimal. As can be seen in the picture, I realized the required 7-pin plug for connection with the rowing machine by inserting soldering nails into a 7-pin tube socket.

Joystick RC with Spektrum DXe transmitter

Overview

This article shows how a Spectrum DXe remote control transmitter can be used with the help of a USB2PPM adapter and a notebook to fly a quadcopter with a joystick.

The project includes the following steps:

- Preparation of the remote control transmitter
- Building of the USB2PPM Adapter
- Download the Joystick2PPM program
- Settings and commissioning

In addition to the remote control transmitter, PC or notebook with Windows 10, USB2PPM adapter and the joystick, a trainer cable is required to connect the remote control transmitter to the USB2PPM and a USB cable.

Preparation of the remote control transmitter

The spectrum DXe remote control transmitter is controlled by the teacher/student jack on the back of the transmitter. An external PPM signal can be fed into this jack – usually from a second transmitter, the student transmitter. The jack is a 3.5 mm standard jack and the cable connection is made via a corresponding mono-aux cable.

In order for the teacher to be able to take control quickly at any time, the student’s signal is only transmitted as long as the teacher pushes the bind / panic button. This practical implementation of the teacher-student operation naturally makes it difficult to take over the transmitter permanently, since you probably cannot or do not want to manually push the button down while flying.

Therefore, I have installed an additional switch in my Spectrum DXe in order to be able to permanently switch the remote control transmitter to student operation. Although the installation is simple, you should only consider it if you accept the likely loss of the warranty.

Installation of the additional switch for permanent student operation

The housing is opened as described in the manual. In the back half of the transmitter housing there is already a hole at the ideal position, which is covered from the outside by a sticker (see red arrow in the picture).

Expose the hole and insert the additional switch (see details).

The wiring is done in such a way that the Bind/Panik/Trainerbutton is shunted (see picture). For this purpose, a short piece of wire is soldered to the small printed circuit board.

I then attached a small arrow on the outside so that I always know in which mode the transmitter would be currently (see picture).

Building of the USB2PPM Adapter

Of the USB2PPM is implemented according to the assembly instructions, but the last step is omitted (soldering in the three-pole PIN bar for the PPM signal). Instead, a 3.5 mm jack is placed in the experimental field of the printed circuit board (see pictures) to connect to the Spectrum DXe.

With this, all hardware bits and pieces for setting up the remote control are ready.

Download the Joystick2PPM program

The Joystick2PPM program takes over the evaluation of the joystick positions and the conversion into corresponding commands to the USB2PPM. This in turn generates the PPM pulse frame as an input signal for the remote control transmitter.

The Joystick2PPM program is free in Microsoft App Store available.

Settings and commissioning

Now connect the USB2PPM adapter and joystick to your PC. When connected for the first time, Windows 10 will automatically install drivers and associate the adapter with a COM port.

After completing the driver installation, start the Joystick2PPM program. The program automatically connects to the USB2PPM and the first joystick it finds and displays the available axes and switches on the left-hand side of the screen.

Now you can start to configure the channels for your application model-specifically.

For this blog I have chosen a Blade INDUCTRIX quadrocopter as an example, but you can of course also connect other copters.

For configuration, assign the joystick controls to the individual channels of the remote control on the right-hand side (the instructions for the model may contain information on how to assign the channels). If you click on the selection box for a channel, all control elements that have not yet been assigned are displayed and you can make your selection for this channel by clicking on them.

As soon as you have made an assignment, the current value for this control element is transferred to the right-hand side as the channel value. You can see the complete configuration for my application in the following screen dump.

Now turn on your transmitter and make sure that the transmitter is “paired” with the remote control model (trainer switch to “off”). Now, without turning off the remote control transmitter, connect the USB2PPM adapter using the training cable with the remote control transmitter. After turning on the trainer switch, you can remotely control your model with the joystick. If necessary, you can perform the trimming for the individual channels and a possible servo direction reversal on the PC.

Arduino Pic Programmer

Overview

If you would search the internet you will find quite some DIY pic programmers. However, those designs often either require a true serial or parallel port instead of an easily available USB port or are designed around a pre-programmed controller assuming access to a programmer.

A compelling alternative would be the use of an Arduino as in the ArdPicProg. Load the Arduino sketch, the host program and add a prototype shield with a very limited number of additional components to build your pic programmer. This programmer features also a ICD connector and an RJ-11 jack (ICD2) interface. The complete project including hard- and software is open source and is released under the GNU General Public License Version 3. You can build your own ArdPicProg by using the especially designed PCB.

The complete setup and the application of the ArdPicProg is described in more detail in the User’s Guide.

Download User Guide ArdPicProg (.pdf, EN)

Host-Software for ArdPicProg

For programming a pic controller a host software would be required. You can select between two options: the terminal program “Ardpicprog” or the “Arduino Pic Programmer” (ArdPicProgHost) with a Windows based graphical user interface. The source code for both programs is Open Source and would be available for download on github.

Arduino Pic Programmer (ArdPicProgHost)

This windows application offers a modern and intuitive way of programming a pic controller.

Controllers which are supported by the Arduino Pic programmer can be read, erased, and written. The user interface and the program options are also described in the User’s Guide.

ArdPicProgHost was programmed with Microsoft VB2010 Express and is released under a GNU General Public License Version 3. The source code is provided through a github repository. The executable (Release 0.2.7) can be downloaded here:

Download ArdPicProg.Exe (.zip Datei)

The software does not require any installation. After downloading and unzipping the program can be executed right away.

PicProgHost (terminal program)

You could also employ the host application “PicProgHost” for programming pic controllers which offers a terminal interface. The application is based on the open source Ardpicprog host software you would find on the ArdpicProg project pages. These pages also provide for a suitable documentation of the program operation.

The original source code has been migrated to a Qt 5 environment and the most recent version is now capable of handling COM ports > 9. The can be downloaded here:>

Download PicProgHost.Exe (.zip Datei)

The source code is available on github. The line commands are fully backwards compatible to Ardpicprog – therefore please refer to the ArdPicProg project pages for more information.

There is no program installation required. The user interface is also described in the User’s Guide.

Arduino sketch “ProgramPic”

The “ProgramPic” Sketch which is required for using the Arduino ArdPicProg shield is released under a GNU General Public License Version 3 The sketch is provided through the ProgramPic github repository.

ArdPicProg printed circuit board

The ArdPicProg PCB is available in the shop.

RC with your web browser – more intuitive and more agile

In previous blogs related to RC with a web browser I presented solutions which were suited for simple and none time critical applications due to the user interface and the system response time.

The initial concept of a button based user control was relatively slow because the web page had to be re-transmitted and rebuild on the client side after each user interaction.

The improved “joystick”-based interface was already deploying AJAX to improve the system agility. However, in order to initiate a command you would have to touch the screen and to stop the movement you would have to touch the screen at another location which is not very intuitive. You would probably expect a movement to last as long as you touch the screen.

The latest version of httpRC presented here does address both requirements based on a button based UI: a command is executed only as long as you touch it in a very agile way.

The source code for the ESP8266-01 is provided through github and the programming itself can be done via the programming adapter described earlier.

Additional information regarding the receiver kit you would find on the respective PiKoder page.

Control your Ardupilot Mega Rover with your Android Smartphone (III)

Overview

The Ardupilot Mega (APM) and other flight controllers are frequently controlled by a PPM stream rather than the parallel input per channel which I described in part 1 of this blog. The new PiKoder/PPM wRX receiver with its PPM frame output brings this capability to you. The connection between the receiver and the flight controller is reduced to a single 3 strand cable as shown in the featured image.

Description

The PiKoder/PPM wRX receiver will be controlled by the udpRC4UGV App as described in part 2 of this blog.

The feature set of the app has been extended to allow you to freely determine the position of the direction and throttle channel within the PPM frame through the app preferences.

To change the channel setting please select the respective preference and enter the channel number (1 .. 8). E.g. the APM Rover configuration features direction on channel 1 and throttle on channel 3.

Please note that setting the APM’s input mode from parallel to PPM requires a jumper between channel 2 and channel 3 input as shown below.

Control your Ardupilot Mega Rover with your Android Smartphone (II)

Overview

As already indicated in the previous blog on the topic “Ardupilot Mega Rover with the smartphone remote control“, now, after some further work on the topic, a new Android(TM) app “udpRC4UGV” with rover-specific functions is available. The most important enhancements are the selection of the flight mode and the toggling of channel 7 making a number of APM special functions available.

Description

As outlined in the previous blog a PiKoder/SSC wRX receiver replaces the standard RC receiver in the rover. The smartphone RC uses WLAN for command transmission: the PiKoder does offer an access point (AP) to which the smartphone will connect.

The remote control app offers a variety of user interfaces: from simple key control to a virtual joystick to an accelerometer-based option.

In addition to the general controls for remote control, each user interface also offers the possibility to choose the flight mode. In addition, channel 7 can be triggered via the “CH7” button (for example, in LEARNING mode, the current position is saved as a waypoint).

The app is available free of charge from the Google Play Store. The User Manual can be downloaded from the PiKoder website; it describes not only the program operation in detail, but also the hardware setup.

Ardupilot Mega Rover remotely controlled with smartphone

Overview

In the standard setup of the Ardupilot Mega (APM) for Rovers you would deploy a conventional RC for manual control: the RC receiver feeds the input channels of the APM with PWM signals for Rover movement and for executing special functions such as switching flight modes.

If you replace the conventional remote control receiver with a PiKoder receiver such as the WLAN receiver PiKoder/SSC wRX, then the Ardupilot can be controlled via a smartphone, for example in the rover configuration. As an user interface, either the Android remote control apps udpRC or picCAR can be used for this application or the browser interfacedescribed in the previous article.

Setting up the rover

First, the APM is loaded with the Mission Planner with the ROVER configuration; a further adjustment of the parameters was not necessary in my case.

The following image shows the very simple hardware setup.

The PiKoder – channel 1 is connected to the APM input 1 (steering) and the PiKoder – channel 2 to the input 3 (throttle). The standard rover wiring is used at the output side (steering servo on channel 1, ESC with BEC on channel 3). In this configuration, the Ardupilot takes over the power supply of the receiver.

The Ardupilot does not respond to PWM signals that are below or exceeding the typical range of approx. 1,000 – 2,000 µs. Therefore, the minimum and maximum values of the pulse values of the PiKoder/SSC have to be adjusted, as shown in the following figure.

For this purpose, the PiKoder Control Center (PCC) is used as described in the User’s Manual for the PiKoder/SSC wRX.

This completes the set up; the function of the apps is described in the user manuals.

Outlook

The implementation of further configurations and functions has now been done and incorporated into the Android app udpRC4UGV, which is described in the continuation of this blog.

Since both the apps are open source and the receiver protocol is disclosed, you can of course also make your own modifications and extensions.