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ER9X Based RC Transmitter 12 Channel PPM Solution

Pixhawk/ArdoPilot/Cleanflight/Betaflight

Setting Guide for 12 Channels V1.0

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TABLE OF CONTENTS

1. INTRODUCTION ...................................................................................................................................................................................... 3 1.1. GOALS ................................................................................................................................................................................................... 3 1.2. OVERVIEW ............................................................................................................................................................................................. 3

2. REQUIRED COMPONENTS ................................................................................................................................................................... 3 3. ADD INTERNAL TRANSMITTER TO ER9X BASED RC TRANSMITTERS ................................................................................. 4

THIS SECTION PROVIDES DETAILED INSTRUCTIONS ON ADDING THE INTERNAL TRASMITTER MODULE TO TURNIGY 9XR, FLYSKY (THE OLD MODELS) AND TURNIGY 9XR PRO RC TRANSMITTERS. ....................................................................................................................................... 4 YOU CAN ADD THE INTERNAL TRASMITTER MODULE TO MANY OTHER RC TRANSMITTERS. MORE INFORMATION CAN BE FOUND ON THE INTERNET. ......................................................................................................................................................................................................... 4 3.1. TURNIGY 9XR, FLYSKY , FS-TH9X (OLD ER9X BASED MODELS) ......................................................................................................... 4

3.1.1. RC Transmitter Settings ................................................................................................................................................................ 4 3.1.2. Internal Transmitter Module Connections and Assembly ............................................................................................................. 4

3.2. TURNIGY 9XR PRO (LATEST ER9X BASED MODELS) ............................................................................................................................ 6 3.2.1. RC Transmitter Settings ................................................................................................................................................................ 6 3.2.2. Internal transmitter module connections and assembly ................................................................................................................ 6

3.3. FRSKY TARANIS ..................................................................................................................................................................................... 7 3.3.1. RC Transmitter Settings ................................................................................................................................................................ 7 3.3.2. Add external Transmitter Module ................................................................................................................................................. 7

4. PPM MERGER - CASCADE THE TWO PPM SIGNALS ON THE FLIGHT CONTROL SIDE .................................................... 8 4.1. INTRODUCTION ...................................................................................................................................................................................... 8 4.2. PPM MERGER MODULE COMPATABILITY ............................................................................................................................................... 9 4.3. PPM MERGER MODULE CONNECTION DIAGRAM ................................................................................................................................... 9 4.4. PPM MERGER PWM CONNECTION ...................................................................................................................................................... 10 4.5. PPM MERGER CHANNELS 13-15 RELAY OUTPUTS ............................................................................................................................... 11 4.6. FAILSAFE ............................................................................................................................................................................................. 11 4.7. STATUS LED ....................................................................................................................................................................................... 11 4.8. THECHNICAL SPECIFICATIONS .............................................................................................................................................................. 12

5. USE CHANNELS 9-12 ON ARDUCOPTER/PIXHAWK .................................................................................................................... 13 5.1. PREREQUISITES: ................................................................................................................................................................................... 13 5.2. TEST EXTENDED AUX CHANNELS ....................................................................................................................................................... 13 5.3. APPLY ARDUCOPTER ACTIONS VIA THE EXTENDED CHANNELS ............................................................................................................ 13 5.4. ENABLE AUX SERVO VIA ONE OF THE EXTENDED CHANNELS .............................................................................................................. 14

6. USE CHANNELS 9-12 ON CLEANFLIGHT/BETAFLIGHT ............................................................................................................ 14

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1. Introduction

1.1. Goals The goal is to use inexpensive stock components to create a PPM stream that can achieve the following:

• Transmit and receive 12 channels of PPM stream

• No S-BUS and expensive SBUS converters (SBUS to PWM, SBUS to CPMM, etc.)

• Save flight controller UART port.

Most flight controllers reserve the UART port for the S-BUS connection though there are limited UART ports. With a PPM connection, you can free the UART port for other important connections (telemetry, GPS, OSD, Radio telemetry, etc.)

• Fit all 12 channels directly into the flight controller and leverage on flight controller capabilities to control channels 9-12 (such as gimbal servos and other transmitter switch controls). Plus, an extra 3 channels to turn ON/OFF other devices.

• Use a standard 8-channel transmitter’s modules and 8-channel PPM receivers.

• Compatibility with different brands of transmitter/receiver sets.

1.2. Overview Two issues need to be addressed:

• ER9X based RC transmitters such as Frsky Taranis , Turnigy 9X (the older models), FS-TH9X, Turnigy 9XR Pro, FlySky, etc. support 16 RC channels, however, transmitter modules such as FrSky DJT/DFT or OrangeRx DSMX/DSM2 only support 8 channels. Even though the RC transmitter can stream 16 channels, the transmitter modules ignore channels 9-16 and solely utilize channels 1-8. The solution for this is adding an internal transmitter module along with the external transmitter.

• With two transmitter modules, we need two receivers on the RC vehicle. There is a simple way to connect the primary receiver’s channels 1-8 to the flight controller and the secondary receiver’s channels 9-12 directly to the servos, however, this document introduces a new solution that feeds channels 1-12 directly into the flight controller and leverages its capability to control the AUX servos such as the gimbal system (servos, Camera shutter etc.). This solution cascades two receivers to generate a 12-channel PPM stream (PPM supports a maximum of 12 channels), which can be fed directly to the flight controller.

2. Required Components

• ER9X based RC transmitters such as Turnigy 9XR (the old models), Turnigy 9XR Pro, FlySky, etc.

• Standard 8-channel external transmitter module such as the FrSky DJT/DFT installed on the transmitter and a compatible 8-channel PPM receiver bind (I used FrSky DJT and D4R-II receiver)

• 8-channel internal transmitter module and a compatible 8-channel PPM receiver (I used the FrSky DHT transmitter module with a D4R-II receiver). You can use any other brand as the internal transmitter and receiver set.

• PPM Merger module (sold on eBay, search for “PPM merger” or “R/C 12 channels CPPM solution”

• Standard RC servo 3-pin cables.

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3. Add Internal Transmitter to ER9X Based RC Transmitters

This section provides detailed instructions on adding the internal trasmitter module to Turnigy 9XR, FlySky (the old models) and Turnigy 9XR Pro RC transmitters.

You can add the internal trasmitter module to many other RC transmitters. More information can be found on the internet.

3.1. Turnigy 9XR, FlySky , FS-TH9X (old ER9X based models)

3.1.1. RC Transmitter Settings • Change the protocol to PPM16. In this mode, PPM channels 1-8 are driving the

external transmitter module, while channels 9-16 send to the trainer port

• Keep the 8-channel setting with the appropriate frame length of your receiver (FrSky D4R- II with the latest firmware installed requires 27mSec frame length).

• You don't need to activate or set any of the trainer settings.

3.1.2. Internal Transmitter Module Connections and Assembly The left picture below outlines the electrical connection of the internal transmitter module.

The internal transmitter module needs to be connected to power and to the trainer PPM signal (channels 9-16).

The power connection in the picture below is actually battery power after the main switch.

External TX/Rx Internal TX/Rx PPM Merger Module

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The right picture above outlines how to assemble the internal transmitter module components into the RC transmitter. The FrSky DHT transmitter is shielded with copper paper wrap, which is connected to the ground (see black wire connected to ground). It is used to eliminate any potential interference with the external transmitter or the RC electrical board.

IMPORTANT: Should you decide to shield the transmitter, make sure to isolate it properly as to avoid a short circuit. Transparent tape is recommended for this step

The FrSky internal transmitter module comes with a mode selection toggle switch (1 way, 2 ways, firmware updates). I replaced it with a DIP switch to eliminate accidental mode selection change.

The picture blow shows the back view of the RC transmitter fully assembled.

The internal transmitter module DIP switch is at the bottom left (green color).

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3.2. Turnigy 9XR Pro (Latest ER9X Based Models)

3.2.1. RC Transmitter Settings • Change the protocol to PPM. In this mode, PPM channels 1-8 are driving the

external transmitter module, while channels 9-16 send to the PPM2 connection (connected to the internal transmitter).

• Proto PPM, keep 8-channels 300uSec setting

o PPM FrLen, set the appropriate frame length of your receiver (FrSky D4R-II with the latest firmware installed requires 27 mSec frame length, otherwise it should be set to 22.5).

o 1st Chan, keep as 1

• PPM2 StartChan, set to Follow (or set to 9)

• PPM2 Channels, set to 8CH

3.2.2. Internal transmitter module connections and assembly The pictures below describe the connections and the assembly.

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3.3. Frsky Taranis

3.3.1. RC Transmitter Settings This section will be updated soon.

3.3.2. Add external Transmitter Module Different from the models mentioned above, the internal transmitter module is factory pre-installed.

PPM channels 1-8 are driving the internal transmitter module.

No technical skill are required, just connect an external transmitter module into the bay located on the back of the radio transmitter (for example Frsky DJT).

PPM channels 9-16 are driving the external transmitter module.

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4. PPM Merger - Cascade the two PPM Signals on the Flight Control Side

4.1. Introduction As previously mentioned, we have two PPM streams that need to be cascaded. The receiver which receives PPM channels 1-8 and the receiver which receives PPM channels 9-16.

• The PPM Merger cascades two 8 channel receiver's PPM streams (PPM1-IN and PPM2-IN) and generates a single 12-channel PPM stream of 32.5 mSec frame length through the PPM-OUT (PPM can support up to 12 channels).

• The PPM-OUT is a clone of the input streams in the appropriate order; PPM1-IN channels 1-8 followed by PPM2-IN channels 1-4.

• In addition, the left over PPM2-IN channels 5-7 output CH13-15, which can be used to turn ON/OFF (using relays) any device such as a camera shutter, landing gear, LED strips, etc. In total, the PPM merger supports 15 channels.

• The PPM merger also has 4 PWM ports that can be directly connected to servos (channels 9-12). These PWM signals are emitted in parallel to the PPM stream.

The picture below outlines the cascaded PPM-OUT signal and the intervals between the frames.

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4.2. PPM Merger Module compatability The PPM Merger module was tested to run smoothly with the following flight controllers:

• Pixhawk (Arducopter 3.4) • Naze32 (Cleanflight 1.13 and Betaflight) • SP Racing F3 (Cleanflight 1.13)

The PPM Merger was tested with several receiver types:

• Frsky 4Dr-II • Frsky D8R-XP • Different brands of PPM encoder module (convert any 8 PWM channels receivers to

one CPPM signal). Check the link below for more info: http://ardupilot.org/copter/docs/common-ppm-encoder.html

Please note: The external transmitter/receiver and the internal transmitter/receiver module sets do not need to be identical or from the same brand. Any receiver that generates a PPM stream will work—the PPM Merger module is capable of syncing with any PPM stream regardless of frame length or dead time define (time between pulses).

4.3. PPM Merger Module Connection Diagram Each of the receivers’ PPM streams should be connected to the PPM Merger module inputs. The receiver which receives PPM channels 1-8 should be connected to PPM1-IN and the receiver which receives PPM channels 9-16 should be connected to PPM2-IN. The PPM Merger receives 5V power from the flight controller and feeds the power to the two receivers via the PPM1-IN and PPM2-IN ports.

The diagram below outlines how to connect the components on the vehicle (plan, drone etc.) side.

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The picture below shows the components assembled on the vehicle (plan, drone etc.) side.

4.4. PPM Merger PWM connection The PPM merger module can also emit PWM signals, which can be directly connected to servo. These PWM signal are emitted in parallel to the PPM stream. The board has 4 PWM ports for channels 9-12. You can use a combination of PWM and PPM channels. For example, one can use channels 9-10 to directly drive servos, while using channels 11-12 to drive other features via the flight controller. The diagram below outlines the PPM merger board layout

Note: This board is designed for low current consumption micro servos. To prevent any potential servo motor noise and over current draws when using more than one servo on the PWM ports, it is recommended to connect the servo directly to the controller’s +5V source (or EBC) as opposed to using the PPM merger module.

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4.5. PPM Merger Channels 13-15 Relay outputs The left over PPM2-IN channels 5-7 output CH13-15, which can be used to turn ON/OFF (using relays) any device such as a camera shutter, landing gear, LED strips, etc. These channels are not part of the PPM stream. CH13-15 relay outputs pins MUST be connected through a transistor which is capable to drive the current draws by the connected device. A transistor with a relay is the safest option. The diagrams below outline the two optional connections. Note: Connecting the output directly to a device might damage the board.

4.6. Failsafe Most receivers have the capability to set fail safe channel values when signal is lost (refer to your receiver documentation on how to set fail safe values). You need to set the fail safe on both receivers. In the event of a lost connection, the receivers will continue to send the PPM stream with the fail safe channels values defined. In this case, the PPM Merge module will continue to send the fail safe channels values sent by the receivers to the flight controllers. The D4R-II receiver can be set to stop transmitting the PPM stream if the transmitter signal is lost. In this case, the PPM Merge Module also stops the PPM stream to the flight controller. This setting is the most recommended for PixHawk flight controller. In such an event, the PixHawk failsafe setting can be set to instruct the drone to land or return home.

4.7. Status LED The status LED shows the PPM1-In and PPM2-In status. The LED will blink at a slow 0.5 second rate to indicate normal operation. The LED will blink rapidly at a fast rate to indicate an error if one or both of the connected receivers do not receiving signal. These are two common situations in which this can occur:

• When powering the board while radio transmitter is OFF (turning ON the transmitter, the LED will blink slow, normal operation).

• When turning OFF the radio transmitter (If the receivers are set to stop transmitting the PPM signal when transmitter signal is lost)

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4.8. Thechnical specifications

• PPM-OUT Frame length: 32.5 mSec

• Pulses length (min/center/max): same as the input streams PPM1-IN and PPM2-IN

• Supply voltage: 4-5.5V

• Size W/H: 25 x 35 mm

• Weight: 4 grams

• PPM in sampling accuracy: 0.5 uSec

• PPM out Replication accuracy: 0.5 uSec

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5. Use Channels 9-12 on ArduCopter/PixHawk

Requires ArduCopter (Version 3.3 and Higher) on PixHawk

5.1. Prerequisites: • PPM support more than 8 Channels (PPM max is 12 channels). • Extended AUX signals (9-12) must be in the range of 1000 to 2000, otherwise

PixHawk will not recognize the signal properly

5.2. Test Extended AUX Channels Radio Calibration must be done so the new PPM structure will be recognized. Perform radio calibration and validate that the extended channels are recognized properly in the result summary (min and max values while the max values should be above 1800). In the example below, you can see 10 and 12 channels configurations

5.3. Apply ArduCopter Actions via the Extended Channels

The extended RC channels can’t be found in the mission planner GUI. Search in the “Full Parameter List” for CHx_OPT, (x representing the RC channel you want to use to apply an action, i.e. CH11_OPT). Select one of the following options: 0:Do Nothing 2:Flip 3:Simple Mode 4:RTL 5:Save Trim 7:Save WP 9:Camera Trigger 10:RangeFinder 11:Fence 12:ResetToArmedYaw 13:Super Simple Mode 14:Acro Trainer 16:Auto 17:AutoTune 18:Land 19:EPM 21:Parachute Enable 22:Parachute Release 23:Parachute 3pos 24:Auto Mission Reset 25:AttCon Feed Forward 26:AttCon Accel Limits 27:Retract Mount 28:Relay On/Off 29:Landing Gear 30:Lost Copter Sound 31:Motor Emergency Stop 32:Motor Interlock 33:Brake

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5.4. Enable AUX Servo via one of the Extended Channels PixHawk has 8 regular outputs and 6 AUX ports. The 6 AUX ports can output PWM to drive a servo. The default for the first 4 outputs is to drive PWM (servos). They are labeled RC9, RC10, RC11, and RC12, while the other two; RC13 and RC14, can be used as input/output ports (i.e. drive relay). Search in the “Full Parameter List” for RCx_FUNCTION, and set it to 1 (1=RC Pass Through). X represents the AUX and RC channels you want to use. For example: setting RC11_ FUNCTION =1 will use RC channel 11 to control the AUX output RC11. Other available options are (not tested): 0:Disabled 1:RCPassThru 2:Flap 3:Flap_auto 4:Aileron 6:mount_pan 7:mount_tilt 8:mount_roll 9:mount_open 10:camera_trigger 11:release 12:mount2_pan 13:mount2_tilt 14:mount2_roll 15:mount2_open 16:DifferentialSpoiler1 17:DifferentialSpoiler2 18:AileronWithInput 19:Elevator 20:ElevatorWithInput 21:Rudder 24:Flaperon1 25:Flaperon2 26:GroundSteering 27:Parachute 28:EPM 29:LandingGear 30:EngineRunEnable When Pass Through option is applied, more controls to tune the servo are available in the “Full Parameter List.” (These are not available through the standard Mission Planner GUI). RCx_MAX , RCx_MIN, RCx_REV, RCx_TRIM, RCx_DZ Note 1: Chapters X.3 and X.4 above (“CHx_OPT” and “RCx_FUNCTION”) can co-exist on the same channel number, allowing you to save some RC channels. For example; CH11_OPT set to “Land” mode with RC11_ FUNCTION set to pass through simultaneously engages a servo that opens the landing gear while the flight control start to land. Note 2: RC9 and RC10 AUX PWM ports are usually reserved for Gimbal servos. It is better to use AUX servo channels starting at RC11 (It appears that Gimbal only works on RC9 and RC10).

6. Use Channels 9-12 on Cleanflight/Betaflight

Cleanflight automatically recognizes the 12-channel PPM stream. Once connected with Cleanflight, configure AUX channels 5-12 to be available for setting different actions.