Add documentation for LightWare GRF250/500

Author: rishabsingh3003

common/source/docs/common-lightware-grf250-lidar.rst

@@ -0,0 +1,66 @@
+.. _common-lightware-grf250-lidar:
+
+==========================
+LightWare GRF250 / GRF500
+==========================
+
+The `LightWare GRF250 <https://lightwarelidar.com/shop/grf-250/>`__ and `GRF500 <https://lightwarelidar.com/shop/grf-500/>`__ are long-range lidar-based rangefinders.
+Both models support serial (UART) communication and provide accurate distance and signal-strength data at configurable update rates.
+
+- GRF250: 0.2 m – 250 m range
+- GRF500: 0.2 m – 500 m range
+
+.. image:: ../../../images/lightware-grf250.png
+   :width: 450px
+
+.. note::
+
+   Support for the LightWare GRF250 and GRF500 sensors was added in ArduPilot 4.7 and later.
+
+Serial Connection
+-----------------
+
+The GRF sensors communicate via UART using 3.3 V or 5 V logic levels.
+Connect the TX of the Lidar to the RX of the autopilot UART port, and the RX of the Lidar to the TX of the same port.
+Also connect GND and 5 V to power the sensor.
+
+.. image:: ../../../images/lightware-grf250-wiring.png
+   :width: 600px
+
+Example (SERIAL4):
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If the GRF is connected to the SERIAL4/5 port and it is the first rangefinder:
+
+- :ref:`SERIAL4_PROTOCOL <SERIAL4_PROTOCOL>` = 9 (Lidar)
+- :ref:`SERIAL4_BAUD <SERIAL4_BAUD>` = 115 (115200 baud)
+- :ref:`RNGFND1_TYPE <RNGFND1_TYPE>` = 45 (LightWareGRF)
+- :ref:`RNGFND1_SCALING <RNGFND1_SCALING>` = 1
+- :ref:`RNGFND1_MIN <RNGFND1_MIN>` = 0.2
+- :ref:`RNGFND1_MAX <RNGFND1_MAX>` = 250 *(for GRF250)* or 500 *(for GRF500)*
+
+If instead you are using the Telem2 port, set :ref:`SERIAL2_PROTOCOL <SERIAL2_PROTOCOL>` = 9 and :ref:`SERIAL2_BAUD <SERIAL2_BAUD>` = 115.
+
+Power note:
+The GRF sensors can draw higher current than typical serial peripherals.
+Check your flight controller’s 5 V peripheral rail limits — an external 5 V supply may be required.
+
+Additional GRF-specific Parameters
+----------------------------------
+
+When :ref:`RNGFNDx_TYPE <RNGFND1_TYPE>` is set to 45 (LightWareGRF) and the autopilot is rebooted, the following additional parameters become available:
+
+- :ref:`RNGFNDx_GRF_RET <RNGFND1_GRF_RET>`: Selects which return type to use (0: FirstRaw, 1: FirstFiltered, 2: LastRaw, 3: LastFiltered).
+- :ref:`RNGFNDx_GRF_ST <RNGFND1_GRF_ST>`: Sets the minimum acceptable return signal strength in dB. Returns weaker than this value are ignored (0 disables filtering).
+- :ref:`RNGFNDx_GRF_RATE <RNGFND1_GRF_RATE>`: Sets the sensor update rate in Hz. GRF250 supports 1–50 readings per second, while GRF500 supports 0.5–10 readings per second.
+
+Testing the Sensor
+------------------
+
+You can view the live distance readings in Mission Planner → Flight Data → Status tab, under the field named “rangefinder1” (or `rangefinder2` / 3 for additional sensors).
+
+.. image:: ../../../images/mp_rangefinder_lidarlite_testing.jpg
+   :target: ../_images/mp_rangefinder_lidarlite_testing.jpg
+
+If values remain at zero, verify serial wiring, baud rate, and power supply.
+

common/source/docs/common-rangefinder-landingpage.rst

@@ -78,6 +78,7 @@ Unidirectional Rangefinders
     LightWare SF10 / SF11 Lidar <common-lightware-sf10-lidar>
     LightWare SF20 / LW20 Lidar <common-lightware-lw20-lidar>
     Lightware SF02 Lidar <common-rangefinder-sf02>
+    LightWare GRF250 / GRF500 Lidar <common-lightware-grf250-lidar>
     Maxbotix I2C Sonar <common-rangefinder-maxbotixi2c>
     Maxbotix Analog Sonar <common-rangefinder-maxbotix-analog>
     Nanoradar NRA24 <common-rangefinder-nra24>