Diff: pressure_sensors.cpp

Revision:

11:5cb7ae8bd831

Parent:

9:95fdcdc0977e

Child:

12:3bc2465b034a

diff -r b2d87404309a -r 5cb7ae8bd831 pressure_sensors.cpp
--- a/pressure_sensors.cpp	Mon Apr 27 19:52:02 2020 +0000
+++ b/pressure_sensors.cpp	Thu May 07 03:52:31 2020 +0000
@@ -1,140 +1,120 @@
 
+/* File inclusion */
 #include "mbed.h"
 #include "stdint.h"
 #include "math.h"
 #include "project_defines.h"
 #include "pressure_sensors.h"
-
+#include "filters.h"
 
 /* Object definition */
 I2C pressure_sensor_01(PRESSURE_SENSOR_01_SDA_PIN, PRESSURE_SENSOR_01_SCL_PIN);
 I2C pressure_sensor_02(PRESSURE_SENSOR_02_SDA_PIN, PRESSURE_SENSOR_02_SCL_PIN);
 
 /* Global variable definition */
-int16_t pressure_01_bin, pressure_02_bin;
 float pressure_01_psi, pressure_02_psi;
 float flow_lpm, volume_ml;
-float lpf_01_prev_out, lpf_02_prev_out;
-
-//float diff_pressure_psi;
 
 char sensor_read_data_buffer[2];
 
+
 /* Function definition */
 
 void Pressure_Sensors_Initialize(void){
     
-    int16_t sensor_01_aux, sensor_02_aux;
-    
-    pressure_sensor_01.frequency(PRESSURE_SENSOR_I2C_CLK_HZ ); 
-    pressure_sensor_02.frequency(PRESSURE_SENSOR_I2C_CLK_HZ );
-    
-    /* Perform an initial measurement */
-
-    pressure_sensor_01.read(PRESSURE_SENSOR_01_SRA, sensor_read_data_buffer, 2);
-    sensor_01_aux = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
+    pressure_sensor_01.frequency(PRESSURE_SENSOR_I2C_CLK_HZ); 
+    pressure_sensor_02.frequency(PRESSURE_SENSOR_I2C_CLK_HZ);
     
-    if(sensor_01_aux < PRESSURE_SENSOR_OUTPUT_MIN){
-        sensor_01_aux = PRESSURE_SENSOR_OUTPUT_MIN;
-    }    
-    
-    pressure_sensor_02.read(PRESSURE_SENSOR_02_SRA, sensor_read_data_buffer, 2);
-    sensor_02_aux = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
-
-    if(sensor_02_aux < PRESSURE_SENSOR_OUTPUT_MIN){
-        sensor_02_aux = PRESSURE_SENSOR_OUTPUT_MIN;
-    }    
-        
-    lpf_01_prev_out = (float)sensor_01_aux;
-    lpf_02_prev_out = (float)sensor_02_aux;
-
+    /* Initialize filters */
+     Pressure_01_Cheby2_LPF(0, 1);
+     Pressure_02_Cheby2_LPF(0, 1);
+     Flow_Cheby2_HPF(0, 1);
+     Flow_FIR_LPF(0,1);
 }
 
 
 void Pressure_Sensors_Read(void){
     
-    int16_t raw_pressure_01_bin, raw_pressure_02_bin;
+    int16_t pressure_01_bin;
+    int16_t pressure_02_bin;
     
-    /* Read binary values */
-    pressure_sensor_01.read(PRESSURE_SENSOR_01_SRA, sensor_read_data_buffer, 2);
-    raw_pressure_01_bin = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
+    /* Read pressure 1 (differential) binary value */
+    
+    sensor_read_data_buffer[0] = 0;
+    sensor_read_data_buffer[1] = 0;
     
-    if(raw_pressure_01_bin < PRESSURE_SENSOR_OUTPUT_MIN){
-        raw_pressure_01_bin = PRESSURE_SENSOR_OUTPUT_MIN;
-    }
-
-    pressure_sensor_02.read(PRESSURE_SENSOR_02_SRA, sensor_read_data_buffer, 2);
-    raw_pressure_02_bin = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
+    pressure_sensor_01.read(PRESSURE_SENSOR_01_SRA, sensor_read_data_buffer, 2);
+    pressure_01_bin = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
+    if(pressure_01_bin < PRESSURE_SENSOR_OUTPUT_MIN){
+        pressure_01_bin = PRESSURE_SENSOR_OUTPUT_MIN;
+    }     
+    
+    /* Read pressure 2 binary value */
     
-    if(raw_pressure_02_bin < PRESSURE_SENSOR_OUTPUT_MIN){
-        raw_pressure_02_bin = PRESSURE_SENSOR_OUTPUT_MIN;
-    }    
+    sensor_read_data_buffer[0] = 0;
+    sensor_read_data_buffer[1] = 0;
     
-    /* Filter binary values */
-    pressure_01_bin = Low_Pass_Filter_01(raw_pressure_01_bin);
-    pressure_02_bin = Low_Pass_Filter_02(raw_pressure_02_bin);
+    pressure_sensor_02.read(PRESSURE_SENSOR_02_SRA, sensor_read_data_buffer, 2);
+    pressure_02_bin = ((sensor_read_data_buffer[0] << 8) | sensor_read_data_buffer[1]) & 0x3FFF;
+    if(pressure_02_bin < PRESSURE_SENSOR_OUTPUT_MIN){
+        pressure_02_bin = PRESSURE_SENSOR_OUTPUT_MIN;
+    }    
     
     /* Calculate pressure values in PSI */
     pressure_01_psi = (pressure_01_bin - PRESSURE_SENSOR_OUTPUT_MIN) * (PRESSURE_SENSOR_PRESSURE_MAX - PRESSURE_SENSOR_PRESSURE_MIN);
     pressure_01_psi = (pressure_01_psi / (PRESSURE_SENSOR_OUTPUT_MAX - PRESSURE_SENSOR_OUTPUT_MIN)) + PRESSURE_SENSOR_PRESSURE_MIN;
-    //pressure_01_psi += PRESSURE_SENSOR_OFFSET_PSI;
+    pressure_01_psi += PRESSURE_SENSOR_01_OFFSET_PSI;
+    
     pressure_02_psi = (pressure_02_bin - PRESSURE_SENSOR_OUTPUT_MIN) * (PRESSURE_SENSOR_PRESSURE_MAX - PRESSURE_SENSOR_PRESSURE_MIN);
     pressure_02_psi = (pressure_02_psi / (PRESSURE_SENSOR_OUTPUT_MAX - PRESSURE_SENSOR_OUTPUT_MIN)) + PRESSURE_SENSOR_PRESSURE_MIN;
-    //pressure_02_psi += PRESSURE_SENSOR_OFFSET_PSI;
+    pressure_02_psi += PRESSURE_SENSOR_02_OFFSET_PSI;
+    
+    /* Filter pressure values */
+    pressure_01_psi = Pressure_01_Cheby2_LPF(pressure_01_psi, 0);
+    pressure_02_psi = Pressure_02_Cheby2_LPF(pressure_02_psi, 0);
+    
 } 
 
 
-
 void Calculate_Flow_From_Pressure(void){
     
     float diff_pressure_psi;
     
-    diff_pressure_psi = pressure_02_psi - pressure_01_psi;
+    diff_pressure_psi = pressure_02_psi - pressure_01_psi;    
     
     if(diff_pressure_psi < 0){
-        flow_lpm = -SPIROMETER_SENSOR_CONSTANT * sqrt(-diff_pressure_psi);    
+        flow_lpm = -SPIROMETER_SENSOR_CONSTANT_OXYGEN * sqrt(-diff_pressure_psi);    
     }else{
-        flow_lpm = SPIROMETER_SENSOR_CONSTANT * sqrt(diff_pressure_psi);  
+        flow_lpm = SPIROMETER_SENSOR_CONSTANT_OXYGEN * sqrt(diff_pressure_psi);  
     }    
-}
-
-void Calculate_Volume_From_Flow(void){
     
-    static float previous_flow_lpm = 0.0;
-    float delta_volume_ml;
-    
-    delta_volume_ml = (PRESSURE_SENSOR_READ_PERIOD_MS * (flow_lpm + previous_flow_lpm)) / 60.0;
-    
-    volume_ml = volume_ml + delta_volume_ml;
-    
-    previous_flow_lpm = flow_lpm;
+    /* Filter flow value */
+    flow_lpm = Flow_FIR_LPF(flow_lpm, 0);
+    flow_lpm = Flow_Cheby2_HPF(flow_lpm, 0);
     
 }
 
-int16_t Low_Pass_Filter_01(int16_t raw_value){
-    
-    float lpf_out, sample_period_sec, div;
+
+/* Simpson's integration */
+
+void Calculate_Volume_From_Flow(void){
+
+    static uint8_t integral_count = 0;
+    static float f_x[3] = {0.0, 0.0, 0.0};
+    float delta_volume_ml;
     
-    sample_period_sec = 0.001 * ((float)PRESSURE_SENSOR_READ_PERIOD_MS);
-    div = sample_period_sec + LPF_RC_CONSTANT_SEC;
+    f_x[2] = f_x[1];
+    f_x[1] = f_x[0];
+    f_x[0] = flow_lpm;
+    
+    integral_count++;
     
-    lpf_out = (((float)raw_value) * (sample_period_sec / div)) +  (lpf_01_prev_out * (LPF_RC_CONSTANT_SEC / div));
-    lpf_01_prev_out = lpf_out;
+    if(integral_count >= 2){
+        delta_volume_ml = ((float)PRESSURE_SENSOR_READ_PERIOD_MS / 180.0) * (f_x[2] + (4 * f_x[1]) + f_x[0]);
+        volume_ml += delta_volume_ml;
+        integral_count = 0;
+    }
     
-    return ((int16_t)lpf_out);
-
 }
 
 
-int16_t Low_Pass_Filter_02(int16_t raw_value){
-
-    float lpf_out, sample_period_sec, div;
-    
-    sample_period_sec = 0.001 * ((float)PRESSURE_SENSOR_READ_PERIOD_MS);
-    div = sample_period_sec + LPF_RC_CONSTANT_SEC;
-    
-    lpf_out = (((float)raw_value) * (sample_period_sec / div)) +  (lpf_02_prev_out * (LPF_RC_CONSTANT_SEC / div));
-    lpf_02_prev_out = lpf_out;
-    
-    return ((int16_t)lpf_out);
-}