Sine.link
This page shows how to setup a sine.engineering sine.link with the Skynode.
You must have access to the sine.link configuration too provided by sine.engineering
There are several different ways to connect the sine.link ground unit to your GCS. The current version of this document shows how to connect it via USB
Setup
Pairing the radios
The initial step is pairing the sine.link radios. For this example, we assume there is one air unit and one ground unit. There is no inherent difference in hardware between the air unit and ground unit, it is simply a configuration option. The ground unit is configured as the Master and the air unit as the Slave
Start the configuration tool and connect the sine.link units via USB to the computer. Both units should show up in the app.

Click the gear icon for the ground unit (1 in the above image) and configure it as a Master.
For this example we're configuring it with a Pre-Shared Key. Switch the encryption mode to "Use Pre-Shared Key (PSK)" and make a note of the key.
When done, make sure you click "Save All" to apply the settings.

Next, configure the air unit, setting the role to Slave, and entering the PSK from the Master.

Once you click "Save All" on the air unit, you should see the two connect and start to exchange messages.

In this example we've set the TX/RX power to 1mW for testing purposes. Make sure you set this to the correct power level for your application
Communication Setup
Once the radios are paired, you can set up the communication streams.
On the air unit, set UART1 to S1 with CRSF at 400000 baud, and UART2 to S2 MAVLink at 57600 baud. UART3 and UART4 can be set to S3/S4 or DROP.


On the ground unit it depends on how you would like to connect the sine.link to your GCS.
For this example we will connect via USB to the MAVLink stream.
Set UART1/UART2/UART4(USB) to DROP, and configure UART3(USB) to S2 with MAVLink.

Power and Skynode Connection
sine.link v1
Supply via UART1 +5V/GND from external 5V BEC
UART2 TX/RX/GND -> Skynode TELEM
UART1 TX/GND -> Skynode RC in
sine.link v1 mono
Supply via +5v pin from Skynode
TX2/RX2/GND -> Skynode TELEM
TX1/GND -> Skynode RC in
sine.link v2
Supply directly from battery via power port
UART2 TX/RX/GND -> Skynode TELEM
UART1 TX/GND -> Skynode RC in
sine.link v2 mono
Supply directly from battery via BAT/GND pads
TX2/RX2/GND -> Skynode TELEM
TX1/GND -> Skynode RC in
On the Skynode S, we suggest using TELEM2 for the MAVlink telemetry. In this case you would wire the sine.link v1 as follows:
UART2 JST-GH pin 2
UART2 TX
TELEM2 RX
EXTRAS 1 JST-GH pin 6
UART2 JST-GH pin 3
UART2 RX
TELEM2 TX
EXTRAS 1 JST-GH pin 5
UART2 JST-GH pin 6
GND
GND
EXTRAS 1 JST-GH pin 10

Skynode Configuration
Next the Skynode needs to be set up with the correct settings for RC input and the telemetry radio on TELEM2.
The following PX4 parameters must be set:
MAV_0_CONFIG
TELEM2
Enable MAVLink via the TELEM2 port
SER_TEL2_BAUD
57600 8N1
Configure the baud rate of the TELEM2 port
RC_CRSF_PRT_CFG
Radio Controller
(Optional) Set the RC in pin to decode crossfire protocol
COM_RC_IN_MODE
Prio: RC > MAVL1 > MAVL2
(Optional) Set the priority of the manual control input to prioritize RC over MAVLink 1 and 2
Once you've set these parameters, reboot your vehicle.
AMC Configuration
Finally, AMC must be configured with a custom comm link. This step depends on how you connect to the sine.link ground unit, for now we assume it's via USB.
The sine.link unit exposes 2 USB CDC-ACM devices (COM ports) when connected via USB. Based on the ground unit configuration earlier, the first port will be the one we connect to.
On Ubuntu, you can easily see which serial ports this is by running ls -l /dev/serial/by-id:
Make a note of the -if01 serial port. In our case it's ttyACM0
Launch AMC, and navigate to Settings -> Comm Links:

Click Add and configure the comm link. Make sure to set the Type to Serial, make sure Low-bandwidth Link is set and that the Serial Port and Baud Rate are set correctly:

Click OK, select the created comm link, and click connect:

You should now be connected to the vehicle over your sine.link radio:

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