Switch to MAVLink for Ground Station communication

CMakeLists.txt

@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 3.12)
 
 project(RocketCode2020 C CXX)
+set(CMAKE_CXX_STANDARD 17)
 
 cmake_host_system_information(RESULT _memfree QUERY AVAILABLE_PHYSICAL_MEMORY)
 set_property(GLOBAL PROPERTY JOB_POOLS four_jobs=4)
@@ -128,6 +129,8 @@ target_link_libraries(MainLoopLib cobs-c)
 
 target_link_libraries(MainLoopLib ${CMAKE_THREAD_LIBS_INIT})
 
+target_link_libraries(MainLoopLib mavlink)
+
 target_link_libraries(MainLoopLib i2c)
 add_executable(MainLoop ./src/init/MainLoop.cpp)
 target_link_libraries(MainLoop MainLoopLib)

libraries/CMakeLists.txt

@@ -58,3 +58,7 @@ target_include_directories(cobs-c PUBLIC ./cobs-c)
 # ---------------
 add_subdirectory(./protobuf-definitions)
 
+# ---------------
+# MAVLink Definitions
+# ---------------
+add_subdirectory(./mavlink)

libraries/mavlink/CMakeLists.txt

@@ -0,0 +1,8 @@
+add_library(mavlink INTERFACE)
+
+target_include_directories(mavlink INTERFACE generated/)
+target_include_directories(mavlink INTERFACE generated/common)
+target_include_directories(mavlink INTERFACE generated/minimal)
+target_include_directories(mavlink INTERFACE generated/uorocketry)
+
+target_compile_options(mavlink INTERFACE -Wno-address-of-packed-member -Wno-cast-align)

libraries/mavlink/generate.sh

@@ -0,0 +1,4 @@
+# This file needs to be ran anytime the MAVLink message definitions are changed.
+# First, install the needed utility: pip install pymavlink
+
+mavgen.py --lang=C++11 --wire-protocol=2.0 --output=./generated ../protobuf-definitions/mavlink/uorocketry.xml

libraries/mavlink/generated/checksum.h

@@ -0,0 +1,95 @@
+#pragma once
+
+#if defined(MAVLINK_USE_CXX_NAMESPACE)
+namespace mavlink {
+#elif defined(__cplusplus)
+extern "C" {
+#endif
+
+// Visual Studio versions before 2010 don't have stdint.h, so we just error out.
+#if (defined _MSC_VER) && (_MSC_VER < 1600)
+#error "The C-MAVLink implementation requires Visual Studio 2010 or greater"
+#endif
+
+#include <stdint.h>
+
+/**
+ *
+ *  CALCULATE THE CHECKSUM
+ *
+ */
+
+#define X25_INIT_CRC 0xffff
+#define X25_VALIDATE_CRC 0xf0b8
+
+#ifndef HAVE_CRC_ACCUMULATE
+/**
+ * @brief Accumulate the CRC16_MCRF4XX checksum by adding one char at a time.
+ *
+ * The checksum function adds the hash of one char at a time to the
+ * 16 bit checksum (uint16_t).
+ *
+ * @param data new char to hash
+ * @param crcAccum the already accumulated checksum
+ **/
+static inline void crc_accumulate(uint8_t data, uint16_t *crcAccum)
+{
+        /*Accumulate one byte of data into the CRC*/
+        uint8_t tmp;
+
+        tmp = data ^ (uint8_t)(*crcAccum &0xff);
+        tmp ^= (tmp<<4);
+        *crcAccum = (*crcAccum>>8) ^ (tmp<<8) ^ (tmp <<3) ^ (tmp>>4);
+}
+#endif
+
+
+/**
+ * @brief Initialize the buffer for the MCRF4XX CRC16
+ *
+ * @param crcAccum the 16 bit MCRF4XX CRC16
+ */
+static inline void crc_init(uint16_t* crcAccum)
+{
+        *crcAccum = X25_INIT_CRC;
+}
+
+
+/**
+ * @brief Calculates the CRC16_MCRF4XX checksum on a byte buffer
+ *
+ * @param  pBuffer buffer containing the byte array to hash
+ * @param  length  length of the byte array
+ * @return the checksum over the buffer bytes
+ **/
+static inline uint16_t crc_calculate(const uint8_t* pBuffer, uint16_t length)
+{
+        uint16_t crcTmp;
+        crc_init(&crcTmp);
+	while (length--) {
+                crc_accumulate(*pBuffer++, &crcTmp);
+        }
+        return crcTmp;
+}
+
+
+/**
+ * @brief Accumulate the MCRF4XX CRC16 by adding an array of bytes
+ *
+ * The checksum function adds the hash of one char at a time to the
+ * 16 bit checksum (uint16_t).
+ *
+ * @param data new bytes to hash
+ * @param crcAccum the already accumulated checksum
+ **/
+static inline void crc_accumulate_buffer(uint16_t *crcAccum, const char *pBuffer, uint16_t length)
+{
+	const uint8_t *p = (const uint8_t *)pBuffer;
+	while (length--) {
+                crc_accumulate(*p++, crcAccum);
+        }
+}
+
+#if defined(MAVLINK_USE_CXX_NAMESPACE) || defined(__cplusplus)
+}
+#endif