Update ELRS information

common/source/docs/common-rc-systems.rst

@@ -137,7 +137,8 @@ Below is a table with some commonly  available systems showing these elements. N
 +-----------------------+------+----------+------------+-----------+--------------+--------+
 |CRSF                   |Long  |  Bi-Dir  |   Variable |  yes      |SBUS/CRSF     |    3   |
 +-----------------------+------+----------+------------+-----------+--------------+--------+
-|ELRS                   |Long  |  Yes     |     -      |   -       |CRSF          |    4   |
+|ELRS                   |Long  |  Bi-Dir  |   Variable |  optional |SBUS/CRSF     |    4   |
+|                       |      |          |            |           | Mavlink      |        |
 +-----------------------+------+----------+------------+-----------+--------------+--------+
 |FLYSKY                 |Short |    No    |     -      |   -       |  IBus        |        |
 +-----------------------+------+----------+------------+-----------+--------------+--------+
@@ -169,7 +170,7 @@ Note 2: See :ref:`common-frsky-yaapu`. The ability to change parameters over FRS
 
 Note 3: ArduPilot provides a means to send its telemetry data via CRSF such that it can be displayed on `OpenTX <https://www.open-tx.org/>`__ transmitters using the :ref:`Yaapu Telemetry LUA Script<common-frsky-yaapu>`. The ability to change parameters over CRSF telemetry from an Open TX compatible transmitter in addition to displaying the telemetry data is also possible. See :ref:`common-crsf-telemetry`
 
-Note 4: ELRS (EpressLRS) is a system that uses the CRSF (TBS Crossfire) RC protocol with several minimizations to simplify the system. It has reduced features but it connects to ArduPilot just like CRSF, when CRSF RXs are attached using a full UART, instead of SBUS protocol to communicate to ArduPilot. See `ExpressLRS site <https://www.expresslrs.org/2.0/>` for more information.
+Note 4: ELRS (ExpressLRS) is a flexible open-source system that can output CRSF, SBUS, or MAVLink (with embedded RC) protocols. Telemetry requires the use of CRSF or Mavlink, and the receiver must be wired to a full UART.  See `ExpressLRS site <https://www.expresslrs.org/>`  and :ref:`TBS CRSF/ ELRS <common-tbs-rc>` for more information.
 
 Note 5: The mLRS project is firmware designed specifically to carry both RC and MAVLink. The usable telemetry speed varies by the chosen mode and is managed via RADIO_STATUS flow control. It uses the CRSF (TBS Crossfire) RC protocol on both the receiver and Tx module.  It also integrates full MAVLink telemetry via serial connections on the Tx module and the receiver.
 
@@ -200,7 +201,7 @@ With integrated telemetry:
     mLRS <common-mlrs-rc>
     Multiplex (no support in ArduPilot for M-Link telemetry yet) <common-multiplex-rc>
     Spektrum SRXL2 <common-spektrum-rc>
-    TBS CRSF <common-tbs-rc>
+    TBS CRSF/ ELRS <common-tbs-rc>
 
 Multi-Protocol:
 

common/source/docs/common-tbs-rc.rst

@@ -8,7 +8,8 @@ Any Crossfire/ELRS compatible receiver can be used with ArduPilot.
 
 .. note::  ELRS (ExpressLRS) RC systems use the CRSF protocol and are connected in a similar manner as Crossfire receivers. Also, on F4/F7 based autopilots the UART MUST be DMA enabled for reliable operation. Consult :ref:`common-autopilots`.
 
-If you do not wish to use telemetry then the receiver can be connected to the **RCIN** port using :ref:`SBUS <common-rc-systems>`. You must configure the Receiver to output SBUS, of course.
+If you do not wish to use telemetry then a TBS Crossfire or ELRS receiver can be connected to the **RCIN** port using :ref:`SBUS <common-rc-systems>`. You must configure the receiver to output SBUS, of course.
+
 
 CRSF Receivers 
 ==============
@@ -47,6 +48,17 @@ Instead of CRSF protocol, MAVLink protocol can be used. In this case, using SERI
 
 If the ELRS transmitter module has WIFI capability, then the telemetry data can be forwarded wirelessly to a PC or phone based GCS close to the transmitter.
 
+MAVLink Option
+--------------
+
+In addition to SBUS and CRSF protocols, ELRS can be configured to use MAVLink protocol for telemetry and embedded RC control. To utilize this attach to SERIAL port 4(as an example) and configure:
+
+- Set :ref:`SERIAL4_PROTOCOL <SERIAL4_PROTOCOL>` = 2
+- Set :ref:`SERIAL4_BAUD <SERIAL4_BAUD>` = 460
+- Set :ref:`RSSI_TYPE <RSSI_TYPE>` =  5
+
+If the ELRS transmitter module has WIFI, the MAVLink telemetry can be wirelessly forwarded to a phone or PC GCS.
+
 CRSF Video Transmitters
 =======================