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移植mavlink协议到STM32详细教程

1准备材料，

首先准备一个带串口的stm32程序（这里选用整点原子的官方串口例程这里自己去找不讲），然后去mavlink官网下载mavlink源码，这里重点讲解这里

a.进入mavlink官网（http://qgroundcontrol.org/mavlink/start），下拉到MAVLink Code and Generator如下图，得到mavlink源码有多种途径，这里选取用python生成。即点击MAVLink Generator (C/C++, Python)

b.然后进入如下界面，点击网址，下面是生成的方法和步骤都写有

c.然后点击clone and downed里面的download zip 即可下载

下载好后解压，然后直接运行mavlink-master里面的mavgenerate.py（python环境自己安装，这里不讲）

然后进入如下界面

点击第一个browse选择message_definitions文件夹里面的v1.0里面的common.xml

然后自己选择输出路径我这里选的新建文件夹

language选择C

protocol选择1.0

然后直接点generate生成

到此材料准备完毕。

2开始真正的移植工作

a.在串口实验里新建一个MAVLINK文件夹，并将刚才生成的文件拷贝过来，如图

打开工程新建分组，将所有拷贝过来的文件和头文件目录添加好，具体这里就不讲了,添加好后如图

b.在main函数中添加#include "mavlink.h"如下

然后编译

"..\OBJ\USART.axf" - 30 Error(s), 17 Warning(s).

一个一个解决。

错误一：

..\MAVLINK\common\../mavlink_types.h(53): error: #20: identifier "pack" is undefined

解决方法：

将mavlink_types.h中

#define MAVPACKED( __Declaration__ ) __pragma( pack(push, 1) ) __Declaration__ __pragma( pack(pop) )

改为

#define MAVPACKED( __Declaration__ )  __Declaration__

这里不使用对齐字节了，直接用也是一样的。

编译后：

"..\OBJ\USART.axf" - 30 Error(s), 7 Warning(s).

错误二：

..\MAVLINK\common\../mavlink_types.h(54): error: #3092: anonymous unions are only supported in --gnu mode, or when enabled with #pragma anon_unions

解决方法：

根据提示信息在mavlink_types.h的前面加入#pragma anon_unions

编译后：

"..\OBJ\USART.axf" - 30 Error(s), 8 Warning(s).

错误三：

..\MAVLINK\common\../checksum.h(34): warning: #260-D: explicit type is missing ("int" assumed)

包括后面很多错误都有共同点，指向有inline的行，这里是因为mdk中无法识别inline

解决方法：

在checksum.h加入一行代码定义inline

#define  inline  __INLINE

编译后：

"..\OBJ\USART.axf" - 4 Error(s), 195 Warning(s).

错误四：

..\MAVLINK\common\../mavlink_conversions.h(167): error: #268: declaration may not appear after executable statement in block

解决方法：

指向定义的变量，将变量的定义放到函数的最前端（四个错误都是这种错误）

以前mavlink_conversions.h的代码

MAVLINK_HELPER void mavlink_dcm_to_quaternion(const float dcm[3][3], float quaternion[4])
{
    float tr = dcm[0][0] + dcm[1][1] + dcm[2][2];
    if (tr > 0.0f) {
        float s = sqrtf(tr + 1.0f);
        quaternion[0] = s * 0.5f;
        s = 0.5f / s;
        quaternion[1] = (dcm[2][1] - dcm[1][2]) * s;
        quaternion[2] = (dcm[0][2] - dcm[2][0]) * s;
        quaternion[3] = (dcm[1][0] - dcm[0][1]) * s;
    } else {
        /* Find maximum diagonal element in dcm
         * store index in dcm_i */
        int dcm_i = 0;
        int i;
        for (i = 1; i < 3; i++) {
            if (dcm[i][i] > dcm[dcm_i][dcm_i]) {
                dcm_i = i;
            }
        }
        int dcm_j = (dcm_i + 1) % 3;
        int dcm_k = (dcm_i + 2) % 3;
        float s = sqrtf((dcm[dcm_i][dcm_i] - dcm[dcm_j][dcm_j] -
                    dcm[dcm_k][dcm_k]) + 1.0f);
        quaternion[dcm_i + 1] = s * 0.5f;
        s = 0.5f / s;
        quaternion[dcm_j + 1] = (dcm[dcm_i][dcm_j] + dcm[dcm_j][dcm_i]) * s;
        quaternion[dcm_k + 1] = (dcm[dcm_k][dcm_i] + dcm[dcm_i][dcm_k]) * s;
        quaternion[0] = (dcm[dcm_k][dcm_j] - dcm[dcm_j][dcm_k]) * s;
    }
}

更改后mavlink_conversions.h的代码

MAVLINK_HELPER void mavlink_dcm_to_quaternion(const float dcm[3][3], float quaternion[4])
{
		int dcm_j,dcm_k;
		float s;
    float tr = dcm[0][0] + dcm[1][1] + dcm[2][2];
    if (tr > 0.0f) {
        float s = sqrtf(tr + 1.0f);
        quaternion[0] = s * 0.5f;
        s = 0.5f / s;
        quaternion[1] = (dcm[2][1] - dcm[1][2]) * s;
        quaternion[2] = (dcm[0][2] - dcm[2][0]) * s;
        quaternion[3] = (dcm[1][0] - dcm[0][1]) * s;
    } else {
        /* Find maximum diagonal element in dcm
         * store index in dcm_i */
        int dcm_i = 0;
        int i;
        for (i = 1; i < 3; i++) {
            if (dcm[i][i] > dcm[dcm_i][dcm_i]) {
                dcm_i = i;
            }
        }
        dcm_j = (dcm_i + 1) % 3;
        dcm_k = (dcm_i + 2) % 3;
        s = sqrtf((dcm[dcm_i][dcm_i] - dcm[dcm_j][dcm_j] -
                    dcm[dcm_k][dcm_k]) + 1.0f);
        quaternion[dcm_i + 1] = s * 0.5f;
        s = 0.5f / s;
        quaternion[dcm_j + 1] = (dcm[dcm_i][dcm_j] + dcm[dcm_j][dcm_i]) * s;
        quaternion[dcm_k + 1] = (dcm[dcm_k][dcm_i] + dcm[dcm_i][dcm_k]) * s;
        quaternion[0] = (dcm[dcm_k][dcm_j] - dcm[dcm_j][dcm_k]) * s;
    }
}

以前mavlink_helpers.h的代码

MAVLINK_HELPER uint16_t mavlink_msg_to_send_buffer(uint8_t *buffer, const mavlink_message_t *msg)
{
	memcpy(buffer, (const uint8_t *)&msg->magic, MAVLINK_NUM_HEADER_BYTES + (uint16_t)msg->len);
	uint8_t *ck = buffer + (MAVLINK_NUM_HEADER_BYTES + (uint16_t)msg->len);
	ck[0] = (uint8_t)(msg->checksum & 0xFF);
	ck[1] = (uint8_t)(msg->checksum >> 8);
	return MAVLINK_NUM_NON_PAYLOAD_BYTES + (uint16_t)msg->len;
}

更改后mavlink_helpers.h的代码

MAVLINK_HELPER uint16_t mavlink_msg_to_send_buffer(uint8_t *buffer, const mavlink_message_t *msg)
{
	uint8_t *ck; 
	memcpy(buffer, (const uint8_t *)&msg->magic, MAVLINK_NUM_HEADER_BYTES + (uint16_t)msg->len);
	ck = buffer + (MAVLINK_NUM_HEADER_BYTES + (uint16_t)msg->len);
	ck[0] = (uint8_t)(msg->checksum & 0xFF);
	ck[1] = (uint8_t)(msg->checksum >> 8);
	return MAVLINK_NUM_NON_PAYLOAD_BYTES + (uint16_t)msg->len;
}

编译后：

"..\OBJ\USART.axf" - 0 Error(s), 195 Warning(s).

解决所有警告的方法：

将protocol.h里面的旧代码

#define _MAV_RETURN_char(msg, wire_offset)             (const char)_MAV_PAYLOAD(msg)[wire_offset]
#define _MAV_RETURN_int8_t(msg, wire_offset)   (const int8_t)_MAV_PAYLOAD(msg)[wire_offset]
#define _MAV_RETURN_uint8_t(msg, wire_offset) (const uint8_t)_MAV_PAYLOAD(msg)[wire_offset]

去掉const，改为

#define _MAV_RETURN_char(msg, wire_offset)             (const char)_MAV_PAYLOAD(msg)[wire_offset]
#define _MAV_RETURN_int8_t(msg, wire_offset)   (int8_t)_MAV_PAYLOAD(msg)[wire_offset]
#define _MAV_RETURN_uint8_t(msg, wire_offset) (uint8_t)_MAV_PAYLOAD(msg)[wire_offset]

编译后：

"..\OBJ\USART.axf" - 0 Error(s), 0 Warning(s).

3开始更改底层串口代码

待续。。。

来自为知笔记(Wiz)

文章来自：http://www.cnblogs.com/lovechen/p/5801679.html