sensor_routines.c

lpc2138读写SD卡的fat文件系统

/******************************************************************************/
/*  This file is part of the kp development                                   */
/*  Copyright kp                                                              */
/******************************************************************************/
/*                                                                            */
/*  wind routines                                       */
/*                                                                            */
/******************************************************************************/

#include <LPC213x.H>                     // LPC21xx definitions
#include <bsp.h>                         // include board support package
#include <math.h>
#include <string.h>

float wind_dir_ave;
char wind_dir_str[3];

// read wind direction bits
int read_wind_dir_bits() {
  int x;
    x = IOPIN0;
    x = x >> 20;
    x = x & 0x00000007;
  return(x); 
}

// Read wind direction
float wind_dir (void) {
  float azmith[8] = {225.0,270.0,315.0,0.0,45.0,90.0,135.0,180.0};
  float tmp;
  tmp = azmith[read_wind_dir_bits()];
// calculate wind direction in degrees 0-> North, 90-> E, etc.
// read io_address and strip out the three bits.
// Average reading and calulate angle
// wind_dir_ave = ((wind_dir_ave*4) + tmp)/5;
   wind_dir_ave = tmp;
  return(wind_dir_ave);
}

void wind_dir_char(void) {
  unsigned char tmp;
  tmp = read_wind_dir_bits();
  switch (tmp) {
    case 0: strcpy(wind_dir_str," E"); break;
    case 1: strcpy(wind_dir_str,"SE"); break;
    case 2: strcpy(wind_dir_str," S"); break;
    case 3: strcpy(wind_dir_str,"SW"); break;
    case 4: strcpy(wind_dir_str," W"); break;
    case 5: strcpy(wind_dir_str,"NW"); break;
    case 6: strcpy(wind_dir_str," N"); break;
    case 7: strcpy(wind_dir_str,"NE"); break;
  }

}
double wind_speed (unsigned int filterred_data) {
  double speed, x, X;
  // Get period from interrupt routine and calculate speed.
  // Interrupt routine averages the data.
  // Calculate wind_speed in MPH
  // Anomometer calibration equation is
  // f(X) = function of freqency	// curve fit equation
  // (24.342758-0.008535973*X+7.410868e-7*X^2), Where X=x^-1.0
  double const A = -1.5562761;
  double const B =  7.78138e7;
  double const C =  1.0;
  double const D =  2118805.0;
  x=(double)filterred_data; // need to capture current value
  							// before interrupt routine modifies
  X=pow(x,-1.0);
  speed=(A+B*X)/(C+D*X);
  if (speed < 0.0) speed = 0.0;
  if (filterred_data > 50000000) speed = 0.0;
  return(speed);
}

float air_temp (unsigned char ad0) {
  float temp, v0;
  // This routine will read the A/D for temperature.
  // The readings are avaeraged.
  // The retuned value if in degrees F 
  // general equation for AN22100
  // Vout=(V/V5)*[1.375+(22.5mv/C)*Ta] 
  // rearanged assuming V/V5 = 1 (V is at 5 volts)
  // Ta= (Vout-1.375)/(0.0225)
  v0=((float)ad0/1023.0)*3.3;	// convert to volts 3.3 reference
  temp = (v0-1.375)/(0.0225); 
return (temp);
} 

float air_temp_F (float air_c) {
  float air_f;
  air_f = ((9.0/5.0)*air_c)	+32.0;
return (air_f);
}