emeter_dcbias.c

基于MSPF449的三相电压表功率的开发程序

//**************************************************************************
//    This program extracts the DC bias from an input signal and returns the AC signal
//    It almost accumulates multiple samples and autodetect when a predeterminted
//    number of complete cycles have been accumulated and the number of samples counted
//    during these number of complete cycles. These information is logged and used
//    by the main routine for further processing.
//
//    Vincent Chan 
//    Texas Instruments Hong Kong Ltd
//    Date        Comments
//    =====================
//    01/09/19    Code Starts
//    01/10/5     module more or less working.
//    01/11/27    Now V zero crossings also does I accumlation. This overcomes the problem
//                of switching range when I may not trigger with the old DC bias.
//**************************************************************************

#include "emeter_3phase.h"
//--------------------------------------------------------------------------

extern long logged_shifted_p_accum,shifted_p_accum;
extern int logged_shifted_p_count,shifted_p_count,shifted_samples_read_index;
    
void extract_dc_bias(long* channel_long_params, int* channel_int_params, int* voltage, int* current)
{
//Accumulate input value.
//Accumulate current and voltage values (used for DC extraction)
channel_long_params[V_accum] += *voltage;
++channel_int_params[V_count];

channel_long_params[I_accum] += *current;
++channel_int_params[I_count];

//extract the average DC bias level so far
//this will turn the signal to a signed singal with zero DC

*voltage-=channel_int_params[V_bias];
*current-=channel_int_params[I_bias];


//do zero crossing for voltage (cycle detection)
if(*voltage<0)
  {
  channel_int_params[channel_status]&=~V_POS;     //log the sign of the signal
  }
else
  {                                             //detect start of a new cycle
                                                //by detection NEG->POS transition
  if(!(channel_int_params[channel_status]&V_POS))
    {                                           //if so see if 64 cycles has been recorded
    if(++channel_int_params[V_cycle_counter]>=64)
      {                                         //once 64 cycles has been recorde
                                                //logged the accumulated values for V and P
      channel_long_params[logged_V_accum]=channel_long_params[V_accum];
      channel_int_params[logged_V_count]=channel_int_params[V_count];
                                                //tell foreground that there are things to process
      channel_int_params[channel_status]|=NEW_V_LOG;
     
      channel_long_params[V_accum]=0;           //reset the accum. and count registers
      channel_int_params[V_count]=0;
      channel_int_params[V_cycle_counter]=0;      
      }
    if(++channel_int_params[P_cycle_counter]>=32)
      {                                         //once 32 cycles has been recorded
                                                //logged the accumulated values for V and P   
      channel_long_params[logged_P_accum]=channel_long_params[P_accum];
      channel_int_params[logged_P_count]=channel_int_params[P_count];
      
      channel_long_params[logged_PS_P_accum]=channel_long_params[PS_P_accum];
      channel_int_params[logged_PS_P_count]=channel_int_params[PS_P_count];  
          
                                                //tell foreground that there are things to process
      channel_int_params[channel_status]|=NEW_P_LOG;
      
      channel_long_params[P_accum]=0;           //reset the accum. and count registers
      channel_int_params[P_count]=0;
      channel_long_params[PS_P_accum]=0;         
      channel_int_params[PS_P_count]=0;       
      channel_int_params[P_cycle_counter]=0;      
      }
    if(++channel_int_params[I_cycle_counter]>=64)
      {      
      channel_long_params[logged_I_accum]=channel_long_params[I_accum];
      channel_int_params[logged_I_count]=channel_int_params[I_count];
      channel_int_params[logged_I_above_threshold_counter]=
            channel_int_params[I_above_threshold_counter];
      channel_int_params[channel_status]|=NEW_I_LOG;
      
      channel_long_params[I_accum]=0;
      channel_int_params[I_count]=0;
      channel_int_params[I_cycle_counter]=0;
      channel_int_params[I_above_threshold_counter]=0;
      }            
    }
  channel_int_params[channel_status]|=V_POS;    //log the sign of the signal
  }  

if(*current<0)                              //same detection is done for current signal
  {
  channel_int_params[channel_status]&=~I_POS;
  }
else
  {
//  if(!(channel_int_params[channel_status]&I_POS))
//    {
//moved to Voltage zero crossing detect
//    }
  channel_int_params[channel_status]|=I_POS;
  if(*current>I_SWITCHING_THRESHOLD)
    {
    ++channel_int_params[I_above_threshold_counter];
    } 
  } 

}