typedef struct sChannelParams
{
    /*!
     * Frequency in Hz
     */
    uint32_t Frequency;
    /*!
     * Data rate definition
     */
    DrRange_t DrRange;
    /*!
     * Band index
     */
    uint8_t Band;
}ChannelParams_t;

typedef union uDrRange
{
    /*!
     * Byte-access to the bits
     */
    int8_t Value;
    /*!
     * Structure to store the minimum and the maximum datarate
     */
    struct sFields
    {
         /*!
         * Minimum data rate
         *
         * EU868 - [DR_0, DR_1, DR_2, DR_3, DR_4, DR_5, DR_6, DR_7]
         *
         * US915 - [DR_0, DR_1, DR_2, DR_3, DR_4]
         */
        int8_t Min : 4;
        /*!
         * Maximum data rate
         *
         * EU868 - [DR_0, DR_1, DR_2, DR_3, DR_4, DR_5, DR_6, DR_7]
         *
         * US915 - [DR_0, DR_1, DR_2, DR_3, DR_4]
         */
        int8_t Max : 4;
    }Fields;
}DrRange_t;
#define LC4                { 867100000, { ( ( DR_5 << 4 ) | DR_0 ) }, 0 }
这里定义了一个结构体类型
但是我强制类型转化就报错了
( ChannelParams_t )LC4
这样我就报错了
说类型转化 不被允许。

LC4是宏吗？
( ChannelParams_t )LC4
宏替换为：
( ChannelParams_t ){ 867100000, { ( ( DR_5 << 4 ) | DR_0 ) }, 0 }

如果 #define LC4 { 867100000, { ( ( DR_5 << 4 ) | DR_0 ) }, 0 } 能通过
试试：
ChannelParams_t a = LC4;