Rocket Altimeter

1//V1   -BMP280 has an accuracy of +-3'.  The initial value is of no concern  as the overall Altitude is determine by subtracting the MIN reading from the MAX  reading. 
2#include "U8glib.h"  //Find and Install this library
3#include  "BMP280.h"  //Find and Install this library
4#include "Wire.h"  //Find and  Install this library
5#define P0 1013.25 //1021.97  //1013.25  //1028.86 //Height  above sea level?  https://whatismyelevation.com/  I really need help with this
6BMP280  bmp;
7
8int piezoPin = 9;  //PIN 9 connected to BUZZERs POSITIVE PIN
9int  waiter = 0;  //Timers Initial State
10int result;
11int resulta;
12int resultb;
13
14U8GLIB_SSD1306_128X64  u8g(U8G_I2C_OPT_NO_ACK);  // OLED DISPLAY Type
15
16char sT[20];
17char sP[9];
18char  sA[9];
19char sA_MIN[9];
20char sA_MAX[9];
21char sA_result[9];
22char sA_resulta[9];
23char  sA_resultb[9];
24double A_MIN = 0;
25double A_MAX = 0;
26
27void draw2(double  T, double P, double A, double A_MIN, double A_MAX, double resulta) {
28  u8g.setFont(u8g_font_unifont);
29
30resulta  = A_MAX - A_MIN;  //Determine difference in feet between the BMP's MIN and MAX readings
31float  resultb = resulta / 3.281;  //Result is in METERS
32
33   dtostrf(A_MIN, 4, 2,  sA_MIN);
34   dtostrf(A_MAX, 4, 2, sA_MAX);
35   dtostrf(resulta, 4, 4, sA_resulta);
36   dtostrf(resultb, 4, 4, sA_resultb);
37  dtostrf(T, 4, 2, sT);
38  dtostrf(P,  4, 2, sP);
39  dtostrf(A, 4, 2, sA);
40
41  u8g.drawStr( 5, 10 , "Feet : ");
42  u8g.drawStr( 60, 10, sA_resulta);
43
44  u8g.drawStr( 5, 30 , "m : ");
45  u8g.drawStr( 60, 30, sA_resultb);
46
47  u8g.drawStr( 5, 45 , "TEMP : ");
48  u8g.drawStr( 60, 45, sT);
49 
50  u8g.drawStr( 5, 62, sA_MAX);
51  u8g.drawStr(  60, 62, sA_MIN);
52  
53}
54
55void setup() {
56
57 pinMode(2, OUTPUT);  //Set  PIN 2 as an OUTPUT for the RED LED
58 pinMode(3, OUTPUT);  //Set PIN 3 as an OUTPUT  for the BLUE LED
59 pinMode(4, OUTPUT);  //Set PIN 4 as an OUTPUT for the Green  LED
60  Serial.begin(9600);
61  if (!bmp.begin()) {
62    Serial.println("BMP  init failed!");
63    while (1);
64  }
65  else Serial.println("BMP init success!");
66
67  bmp.setOversampling(4);
68
69  u8g.setColorIndex(1);
70  u8g.setFont(u8g_font_unifont);
71}
72
73
74void  loop(void) {
75
76int redl = 2;  //Name Pin 2 redl
77int white = 3; //Name PIN  3 white
78int redr = 4; //Name Pin 4 redr
79
80int wait = 50;  //delay in ms,  1000ms equals one second
81int wait2 = 30;  // delay in ms, 1000ms equals one second
82int  wait3 = 10;  // delay in ms, 1000ms equals one second
83
84waiter = waiter + 1;  //Increases the VALUE of WAITER by ONE every PROGRAM CYCLE
85if (waiter >= 600)  tone(piezoPin, 2000, 50);  // Set Buzzer Delay based on # of program cycles.  Sets  Buzzers frequency and how long it beeps for
86
87digitalWrite(redl, HIGH); //  turn the redl LED ON
88delay(wait2); // PAUSE
89digitalWrite(redl, LOW); // turn  the redl LED OFF
90delay(wait); // PAUSE
91
92digitalWrite(white, HIGH); // turn  the white LED ON
93delay(wait2); // PAUSE
94digitalWrite(white, LOW); // turn  the white LED OFF
95delay(wait); //PAUSE
96
97digitalWrite(redr, HIGH); // turn  the redr LED ON
98delay(wait2); // PAUSE
99digitalWrite(redr, LOW); // turn the  redr LED OFF
100delay(wait); //PAUSE
101
102  double T, P;
103  char result = bmp.startMeasurment();
104
105  if (result != 0) {
106    delay(result);
107    result = bmp.getTemperatureAndPressure(T,  P);
108
109    if (result != 0) {
110      double A = bmp.altitude(P, P0);
111
112      if ( A > A_MAX) {
113        A_MAX = A;
114      }
115
116      if ( A < A_MIN  || A_MIN == 0) {
117        A_MIN = A;
118      }
119
120      do {
121        draw2(T,  P, A, A_MIN, A_MAX, resulta);    //(A_MIN, A_MAX, resulta);  //Tells the program  to go to DRAW2
122      } while ( u8g.nextPage() );
123      u8g.firstPage();
124      delay(wait3);
125     
126    }
127    else {
128      Serial.println("Error.");
129    }
130  }
131  else {
132    Serial.println("Error.");
133  }
134
135  delay(wait3);
136
137}
138