Imitation SBUS fixed with serial data conversion

写在前面

  无论如何,Data is definitely an issue that cannot be avoided in embedded.Messy data doesn't make much sense.So we need to package the data at the source,组帧,再进行传输;Unpack after reaching the terminal,还原,Read out the raw data.

编程思路

  This function is used in a simple environmental detection project,使用到了LoRa模块,It can be directly driven by the serial port of the microcontroller.但是使用的STM32F1系列单片机ADC为12位,Storage variables and only8位或16位,This requires data conversion.SBUSThe frame header in the protocol is 0x0F,帧尾为0x00,The penultimate byte is the flag byte,It is planned to be an urgent flag byte,For example, the normal situation is to report the surrounding environment of the collection node at an interval of time;But there is a fire or other data exceeds the threshold,则立即发送数据.But this time the focus is on how to convert,为求简便,Checksums are not considered.

构建结构

typedef struct _SBUSData_Struct              
{
      
    uint16_t                  Channel[8];
    uint8_t           	      FlagByte;
} SBUSData_Struct;

具体函数

1.Convert serial data to analogSBUS数据.

ErrorStatus Map_SCOMtoSBUS(SBUSData_Struct *SBUSdata,uint8_t *SCOMdata)
{
    
    uint8_t    ii;
    
    if((SCOMdata == NULL) | (SCOMdata[0] != 0x0F)|(SCOMdata[13] != 0x00))
    {
    			
        return ERROR;
    }
    
    SBUSdata->FlagByte    = *(SCOMdata +12);
    SBUSdata->Channel[0]  = ((*(SCOMdata +2)<<8)  | (*(SCOMdata +1))>>0)&0x07FF;
    SBUSdata->Channel[1]  = ((*(SCOMdata +3)<<5)  | (*(SCOMdata +2))>>3)&0x07FF;
    SBUSdata->Channel[2]  = ((*(SCOMdata +5)<<10) | ((*(SCOMdata +4))<<2)																								| ((*(SCOMdata +3))>>6))&0x07FF;
    SBUSdata->Channel[3]  = ((*(SCOMdata +6)<<7)  | (*(SCOMdata +5))>>1)&0x07FF;
    SBUSdata->Channel[4]  = ((*(SCOMdata +7)<<4)  | (*(SCOMdata +6))>>4)&0x07FF;
    SBUSdata->Channel[5]  = ((*(SCOMdata +9)<<9)  | ((*(SCOMdata +8))<<1)																									| ((*(SCOMdata +7))>>7))&0x07FF;
    SBUSdata->Channel[6]  = ((*(SCOMdata +10)<<6) | (*(SCOMdata +9))>>2)&0x07FF;
    SBUSdata->Channel[7]  = ((*(SCOMdata +11)<<3) | (*(SCOMdata +10))>>5)&0x07FF;
    
    for(ii = 0; ii < 8; ii++)
    {
    
        if(SBUSdata->Channel[ii] > 2047)
        {
    
            SBUSdata->Channel[ii] = 2047;
        }
    }        
    
    return SUCCESS;		
}

2.will imitateSBUS数据转换为串口数据.

ErrorStatus Map_SBUStoSCOM(uint8_t *SCOMdata,SBUSData_Struct *SBUSdata)
{
    
    uint8_t    ii;	
    uint16_t    Tempdata[16];
    
    if(SBUSdata == NULL)
    {
    
        return ERROR;
    }
    
    *(SCOMdata + 0) = 0x0F;	
    *(SCOMdata + 13) = 0x00;	
    *(SCOMdata + 12) = SBUSdata->FlagByte; 
    
    for(ii=0;ii<8;ii++)
    {
    
        Tempdata[ii] = SBUSdata->Channel[ii] & 0x07FF;
    }
    
    *(SCOMdata + 1)  = Tempdata[0] & 0xFF;
    *(SCOMdata + 2)  = (Tempdata[0]>>8)|(Tempdata[1]<<3);	
    *(SCOMdata + 3)  = (Tempdata[1]>>5)|(Tempdata[2]<<6);	
    *(SCOMdata + 4)  = (Tempdata[2]>>2);	
    *(SCOMdata + 5)  = (Tempdata[2]>>10)|(Tempdata[3]<<1);
    *(SCOMdata + 6)  = (Tempdata[3]>>7)|(Tempdata[4]<<4);
    *(SCOMdata + 7)  = (Tempdata[4]>>4)|(Tempdata[5]<<7);	
    *(SCOMdata + 8)  = (Tempdata[5]>>1);	
    *(SCOMdata + 9)  = (Tempdata[5]>>9)|(Tempdata[6]<<2);
    *(SCOMdata + 10) = (Tempdata[6]>>6)|(Tempdata[7]<<5);
    *(SCOMdata + 11) = (Tempdata[7]>>3);	
    
    return SUCCESS;
}

写在后面

  帧头和帧尾是固定的,The flag byte is not considered for the time being,Because if only“紧急情况”与“普通情况”,The number of data bits is sufficient.本质上就是11个8bit的数据转换成8个11bit的数据.Although it is still when defining variablesuint16_t,即unsigned short int.But that's because computers are binary,I can't define11位的数据,But I can define16位的数据,但只用到11位.For example, the function also has a greater than2047便等于2047的操作.因为12位ADC,最大值应该是4095,But all in one11位,So there is this operation.
  A single copy of the communication format,When I first came into contact with it, I was devastated,Let alone a more complete protocol,There are too many things to consider.还是要继续学习.
  If the data requirements are only in binary,11Bits can also be transferred12位的数据,Shift right by one bit before transmission,Shift left one bit after transmission,can be restored.