bug fix for calculating ppm

diff --git a/src/co2-sensor.c b/src/co2-sensor.c
index ce85c21..7b6cad5 100644 (file)
--- a/src/co2-sensor.c
+++ b/src/co2-sensor.c
@@ -36,7 +36,7 @@ static const double log400 = 2.602;
 
 static bool initialized = false;
 static double co2_zp_volt = -1;
-static double slope_value = -1;
+static double slope_value = 10000;
 
 void co2_sensor_close(void)
 {
@@ -65,9 +65,7 @@ int co2_sensor_read(int ch_num, unsigned int *out_value)
 
 static inline double __value_to_volt(unsigned int value)
 {
-       return (double)value
-               * (double)(CO2_SENSOR_REF_VOLTAGE / CO2_SENSOR_VALUE_MAX)
-               / CO2_SENSOR_VOLTAGE_GAIN;
+       return (double)value * CO2_SENSOR_REF_VOLTAGE / CO2_SENSOR_VALUE_MAX / CO2_SENSOR_VOLTAGE_GAIN;
 }
 
 static double __calc_slope(double zp_volt, double sec_volt, double x_axis_diff)
@@ -82,13 +80,12 @@ int co2_sensor_set_calibration_values(unsigned int zero_point_v,
        double sec_volt = -1;
        double x_axis_diff = -1;
 
-       retv_if(zero_point_v <= second_point_v, -1);
+       retvm_if(zero_point_v <= second_point_v, -1, "%u - %u", zero_point_v, second_point_v);
        retv_if(second_point_ppm <= 400, -1);
 
        co2_zp_volt = __value_to_volt(zero_point_v);
        sec_volt = __value_to_volt(second_point_v);
-       x_axis_diff = log400 - log(second_point_ppm);
-
+       x_axis_diff = log400 - log10(second_point_ppm);
        slope_value = __calc_slope(co2_zp_volt, sec_volt, x_axis_diff);
 
        return 0;
@@ -110,14 +107,16 @@ unsigned int co2_sensor_voltage_to_ppm(double voltage)
 
        /* Example */
 #ifdef USE_EXAMPLE_CODE
-       if (slope_value < 0)
+       if (slope_value > 0)
                co2_sensor_set_calibration_values(CO2_SENSOR_DEFAULT_VALUE_ZP,
-                       CO2_SENSOR_DEFAULT_VALUE_1000, 1000);
+                               1000, CO2_SENSOR_DEFAULT_VALUE_1000);
 
        if (voltage >= co2_zp_volt)
                return 400;
 
        ppm = pow(10, (voltage - co2_zp_volt)/slope_value + log400);
+//     if (ppm > 10000)
+//             ppm = 10000;
 #endif
 
        return (unsigned int)ppm;