OpenTX - Application Note 33
S6R Receiver Set Up
This application sets up an S6R receiver for use in a Slick 360 plane.
The S6R operating modes are as follows.
Normal : the channel signals are passed through to the servos without stabilisation.
Stabilisation : compensate for turbulance is made on aileron, elevator and rudder.
Automatic Level : aileron and elevator stick movements from centre control aircraft angle from horizontal. With sticks centred, aircraft flies level.
Hover : Elevator and rudder control the aircraft in nose up attitude. Throttle controls altitude. Aileron controls rotation.
Knife Edge : Aileron and rudder control aircraft in sideways attitude with wings up and down. Elevator controls steering. Throttle and rudder control altitude.
The operating mode is controlled using channels 10 and 11.
In stabilisation mode, the stabilisation gain is controlled by channel 9.
The S6R determines the channel assignment. Set up the Taranis channels as follows.
Channels 10 and 11 together determine the mode.
Switch SE is used to control channel 10 as follows.
Switch SA is used to control channel 11 as follows.
The following mixer lines are used to set up channels 9, 10, 11 and 12.
S1 pot is used to control the stabilisation gain via channel 9.
The S6R interprets the channel 9 PWM value as shown in the following left hand graph.
To make pot S1 produce a gain range of 0 to 100% as it it turned from 0° to 270°, channel 9’s weight is 50% and it’s offset is 50%. This is shown in the right hand graph above.
Moving channel 12 away from 1500uS PWM (PWM <1450uS or PWM > 1550uS) initiates the self check so channel 12 is set to be always 1500uS. This prevents the self check being accidently initiated during flight. For more information see here.
Mode selection is summarised as follows.
Audio files are used to announce the S6R mode when it changes.
Logic switches calculate which mode is selected from the SE SA switch combination.
The S6R is in normal mode for switch combinations not otherwise specified here, so LS16 is on when no other mode is selected.
The audio file for normal mode announces “Mode normal” with filename modnorm.wav.
Special functions announce the mode audio files.
The S6R uses channels up to channel 12, so on the Model Setup screen, set the channel range of the Internal RF module as follows.
1. On the S6R receiver, press the F/S switch while applying power. The green LED is on.
2. On the Taranis in the Model Set Up screen under the ‘Internal RF’ heading, use the ‘-‘ and ‘+’ keys to select the ‘[Bind]’ parameter. Press ENT to bind the Taranis model to the receiver. The Taranis beeps and the [BIND] text flashes while in binding mode.
3. After about one second, the receiver red LED flashes. This indicates that binding has been completed. On the Taranis, press EXIT to exit the bind mode.
4. Disconnect power to the receiver.
5. Reconnect power and confirm that the receiver is bound. The green LED is on constantly for normal operation. The red LED flashes slowly if the receiver is not receiving signal.
The failsafe settings are set in the Taranis.
(The F/S button does not set the failsafe settings. It performs the self check! See here.)
Ensure to set channels 9, 10, 11 and 12 as well as the usual aileron, elevator, throttle and rudder when you set the failsafe settings.
Here, under failsafe conditions, the throttle is minimum, ailerons, elevator, rudder are centred, the stabilisation gain is 40, channels 10 and 11 select Auto Level mode and channel 12 disables the self check.
I recommend that the preflight switch check checks for SE- which sets normal flight mode.
To remind me which mode is which, this notice is stuck to an aluminium bracket screwed to the neckband lug.
I found upgrading the firmware was not necessary for the S6R to work OK. However, the firmware of the S6R receiver can be upgraded using the STK, the FrSky SPORT upgrade adapter software and an .frk type firmware file.
Download the file ‘firmware-S6R.rar’ from the following web site.
This is a compressed file so decompress it. To decompress it, I use the free Ap ‘Open RAR’.
Folder ‘FCC’ contains the file ‘S6R_FCC_20160816.frk’. (International version)
Folder ‘LBT contains the file ‘ S6R_LBT_20160816.frk’. (European version)
Download the file ‘FrSky SPORT upgrade adapter.zip’ from the following web site.
Unzip this file. The executable file is ‘frsky_update_Sport.exe’
Set the STK switch to ‘Upgrade’, plug the STK into the PC and then connect the S6R as follows.
Run the ‘frsky_update_Sport.exe’ application.
1. Select the COM port that the STK uses and load the firmware file ‘S6R_FCC_20160816.frk’ (for international users).
2. Click ‘Download’ to start.
3. The bar graph shows progress and it takes about 3.5 minutes to complete.
4. On completion, click ‘End’ and the Upgrade application disappears.
Disconnect the S6R and remove the STK from the PC.
The Lua scripts for S6R configuration do not run with OpenTx v2.1. OpenTX v2.2 is required but that is not yet available for an X9D Taranis Plus. The script causes an error when run so I use the alternative way of configuring the S6R, the STK.
Use the STK (Smart port Tool Kit) and the PC configuration software to configure the S6R receiver.
Download the configuration software from here.
Before running the S6R Configuration Software, find out which COM port is created by your PC when you insert the STK into a USB port of your PC.
Check the STK COM Port
Connect the STK module into the PC.
In the Device manager under ‘Ports (COM & LPT)’, check which comport is allocated to the ‘Silicon Labs CP210x USB to UART Bridge’. In the following case, COM3 is allocated.
This COM port number is used when the S6R Configuration software is run.
On the STK, put the switch in the ‘CONFIG’ position. Plug the STK into the PC. Connect the STK via the cable to the S6R Smart Port. The S6R red LED slowly flashes.
WARNING Do not connect to the S6R while the servos are also connected to the S6R. The current drain caused by the servos may exceed the PC USB 5V supply rating! USB 2.0 can supply only 500mA and USB 3.0 can supply only 900mA.
Run the S6R Configuration software.
To enable all the S6R stabilisation features, ensure ‘S6R Enable’ is ticked. The default state is enabled. Otherwise, all stabilisation is disabled.
Connect to the S6R Receiver.
Next to ‘Serial’, select the COM port number that was shown in the Device Manager. In this case it is COM3. Click ‘Open’. The ‘Open’ button changes to ‘Close’ and the ‘Read’ and ‘Write’ buttons are enabled.
Offset Angle Setting
Writing the Configuration to the Receiver
To transfer the configuration from the Configuration Software to the S6R, click the ‘Write’ button. While the data is being written to the receiver, the message ‘Tip: Writing configuration’ is displayed in red text. When the writing is complete, the message ‘Complete write configuration’ is displayed in green text.
NOTE If an error appears instead of the completed message, it is probably because your USB is v2.0 instead of v3.0. The data, however, has probably been written correctly. You can verify this by reading from the S6R.
Reading the Configuration from the Receiver
To transfer the configuration from the S6R to the Configuration Software, click the ‘Read’ button. While the data is being read, the message ‘Tip: Reading configuration’ is displayed in red text. When reading is complete, the message ‘Complete read configuration’ is displayed in green text.
The configuration that was in the S6R can now be viewed on each of the configuration screens.
Completing the Configuration
Click ‘Close’ to close communication with the STK and the receiver.
Disconnect the receiver and the STK.
I have chosen to disable the Taranis control of the self check. (See here.) Instead I recommend using the F/S button on the S6R to perform the self check.
Self Check Procedure
1. Turn on the Taranis and ensure the aileron, elevator and rudder sticks in the neutral positions.
2. Power up the aircraft and keep it stationary while the S6R performs its initialisation.
3. Orientate the aircraft with the slightly nose up attitude it would have in level flight and level wings.
4. Press the button on the S6R while keeping the aircraft still.
5. The blue LED is on during the self check. When the blue LED turns off, the self check is complete.
6. Now set the range of each channel. Move all the sticks except the throttle so that all the servos are moved to their physical limits. (Use high rates.) Move S1 from full anticlockwise to full clockwise. Select all 3 positions on switches SE and SA.
7. Remove power to the S6R. All the configuration values will be saved.
With the throttle off, select the following modes and check the control surface movements.
In Stabilisation mode, the gain, controlled pot S1, should be set when the aircraft is flying full speed with full control surface range. Start with the gain at a low value. Set the gain so that the control surfaces do not oscillate.
In Hover mode, the range of movement of the elevator and rudder was not enough to hold the aircraft correctly so the ranges were increased.
In Knife Edge mode, the air speed needs to be manually controlled to maintain constant altitude. Also the roll angle was not vertical so an offset was needed in the Configuration software.
In Auto Level mode, the aircraft held altitude so no adjustment was required. Manual control is still possible but when the sticks are centred, it flies level.
Disconnecting the servos to make configuration changes is a test of patience, but otherwise, the S6R performs well.