From 653b554a3151b3f4f5c3d74b421c6b03a3798bf5 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 21 Apr 2020 13:29:26 +1000
Subject: [PATCH] SITL: add simulated mavlink-attached rangefinder

---
 libraries/SITL/SIM_RF_MAVLink.cpp | 64 +++++++++++++++++++++++++++++++
 libraries/SITL/SIM_RF_MAVLink.h   | 45 ++++++++++++++++++++++
 libraries/SITL/SIM_Vicon.h        |  1 +
 3 files changed, 110 insertions(+)
 create mode 100644 libraries/SITL/SIM_RF_MAVLink.cpp
 create mode 100644 libraries/SITL/SIM_RF_MAVLink.h

diff --git a/libraries/SITL/SIM_RF_MAVLink.cpp b/libraries/SITL/SIM_RF_MAVLink.cpp
new file mode 100644
index 0000000000..93e24c6950
--- /dev/null
+++ b/libraries/SITL/SIM_RF_MAVLink.cpp
@@ -0,0 +1,64 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+  Simulator for the MAVLink Serial rangefinder
+*/
+
+#include "SIM_RF_MAVLink.h"
+
+#include <GCS_MAVLink/GCS.h>
+
+#include <stdio.h>
+#include <string.h>
+
+using namespace SITL;
+
+uint32_t RF_MAVLink::packet_for_alt(uint16_t alt_cm, uint8_t *buffer, uint8_t buflen)
+{
+    // we share channels with the ArduPilot binary!
+
+    // we're swiping the Vicon's channel here.  If it causes issues we
+    // may need to allocate an additional mavlink channel for the rangefinder
+    const mavlink_channel_t mavlink_ch = (mavlink_channel_t)(MAVLINK_COMM_0+5);
+    if (!valid_channel(mavlink_ch)) {
+        AP_HAL::panic("Invalid mavlink channel");
+    }
+
+    mavlink_message_t msg;
+    const uint8_t system_id = 32;
+    const uint8_t component_id = 32;
+    const mavlink_distance_sensor_t distance_sensor{
+        time_boot_ms: AP_HAL::millis(),
+        min_distance: 10, // cm
+        max_distance: 10, // cm
+        current_distance: alt_cm,
+        type: 0,
+        id: 72, // ID
+        MAV_SENSOR_ROTATION_PITCH_270,
+        255, // 255 is unknown covariance
+        0, // 0 is unknown horizontal fov
+        0, // 0 is unknown vertical fov
+        {0,0,0,0} // unknown/unused quat
+    };
+    const uint16_t len = mavlink_msg_distance_sensor_encode(system_id,
+                                                            component_id,
+                                                            &msg,
+                                                            &distance_sensor);
+    if (len > buflen) {
+        AP_HAL::panic("Insufficient buffer passed in");
+    }
+    const uint16_t retlen = mavlink_msg_to_send_buffer(buffer, &msg);
+    return retlen;
+}
diff --git a/libraries/SITL/SIM_RF_MAVLink.h b/libraries/SITL/SIM_RF_MAVLink.h
new file mode 100644
index 0000000000..cc5c284cb4
--- /dev/null
+++ b/libraries/SITL/SIM_RF_MAVLink.h
@@ -0,0 +1,45 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+  Simulator for the NMEA serial rangefinder
+
+./Tools/autotest/sim_vehicle.py --gdb --debug -v ArduCopter -A --uartF=sim:rf_mavlink --speedup=1
+
+param set SERIAL5_PROTOCOL 1
+param set RNGFND1_TYPE 10
+graph RANGEFINDER.distance
+graph GLOBAL_POSITION_INT.relative_alt/1000-RANGEFINDER.distance
+reboot
+
+arm throttle
+rc 3 1600
+*/
+
+#pragma once
+
+#include "SIM_SerialRangeFinder.h"
+
+namespace SITL {
+
+class RF_MAVLink : public SerialRangeFinder {
+public:
+
+    uint32_t packet_for_alt(uint16_t alt_cm, uint8_t *buffer, uint8_t buflen) override;
+
+private:
+
+};
+
+}
diff --git a/libraries/SITL/SIM_Vicon.h b/libraries/SITL/SIM_Vicon.h
index e114df1e6f..376c1bedd5 100644
--- a/libraries/SITL/SIM_Vicon.h
+++ b/libraries/SITL/SIM_Vicon.h
@@ -43,6 +43,7 @@ private:
     const uint8_t component_id = 18;
 
     // we share channels with the ArduPilot binary!
+    // Beware: the mavlink rangefinder shares this channel.
     const mavlink_channel_t mavlink_ch = (mavlink_channel_t)(MAVLINK_COMM_0+5);
 
     uint64_t last_observation_usec;