HeliosCube-Eleni: A Cost-Effective, Open-Source 1U CubeSat for Microgravity Research

1/*
2
3#mpla-ExoTech
4#DLR
5
6HeliosCube-Eleni
7-A Cost-Effective, Open-Source 1U CubeSat for Microgravity Research
8
9@Petros Mand
10-Athens, 08/12025
11
12*/
13
14#include <Wire.h>
15#include <SPI.h>
16#include <SD.h>
17#include "DFRobot_GNSS.h"
18#include "DFRobot_BNO055.h"
19#include "DFRobot_BMP280.h"
20#include "DFRobot_Geiger.h"
21
22#define SD_CS_PIN D7
23#define SEA_LEVEL_PRESSURE 1015.0f
24#define UV_SENSOR_PIN A4
25#define GEIGER_PIN D6
26#define MIC_PIN A5
27#define LOG_INTERVAL 100  
28#define FLUSH_INTERVAL 100  
29#define SAMPLE_RATE 48000  
30#define SAMPLE_PERIOD (1000000UL / SAMPLE_RATE)  
31
32#define DEBUG 1
33#if DEBUG
34  #define DEBUG_PRINT(x) Serial.println(x)
35#else
36  #define DEBUG_PRINT(x)
37#endif
38
39DFRobot_GNSS_I2C gnss(&Wire, GNSS_DEVICE_ADDR);
40typedef DFRobot_BNO055_IIC BNO;
41BNO bno(&Wire, 0x28);
42typedef DFRobot_BMP280_IIC BMP;
43BMP bmp(&Wire, BMP::eSdoLow);
44DFRobot_Geiger geiger(GEIGER_PIN);
45
46File dataFile;
47File alertFile;
48File audio8k;
49File audio12k;
50File audio16k;
51
52unsigned long lastLogTime = 0;
53unsigned long lastFlushTime = 0;
54unsigned long nextSampleTime = 0;
55
56bool liftOffDetected = false; 
57float maxPressure = 0;
58bool maxQLogged = false;
59bool microgravityLogged = false;
60bool tropopauseLogged = false;
61bool stratosphereLogged = false;
62
63void logAlert(String message, sTim_t utc) {
64  alertFile = SD.open("/hcelenimissiondataalert.csv", FILE_APPEND);
65  if (alertFile) {
66    alertFile.print(utc.hour); alertFile.print(":");
67    alertFile.print(utc.minute); alertFile.print(":");
68    alertFile.print(utc.second); alertFile.print(",");
69    alertFile.println(message);
70    alertFile.close();
71    DEBUG_PRINT("Alert: " + message);
72  } else {
73    DEBUG_PRINT("Error writing alert to SD!");
74  }
75}
76
77String formatCSVData(sTim_t date, sTim_t utc, sLonLat_t lat, sLonLat_t lon, double altitude, float temp, uint32_t press, float baroAltitude, BNO::sAxisAnalog_t acc, BNO::sAxisAnalog_t gyr, BNO::sAxisAnalog_t mag, float uvIndex, int cpm, float nSv, float uSv, uint8_t sats, double sog, double cog, BNO::sEulAnalog_t eul) {
78  char buffer[512];
79  snprintf(buffer, sizeof(buffer), "%04d/%02d/%02d,%02d:%02d:%02d,%.6f,%.6f,%.2f,%.2f,%u,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%.2f,%d,%.2f,%.2f,%u,%.2f,%.2f,%.2f,%.2f,%.2f",
80           date.year, date.month, date.date, utc.hour, utc.minute, utc.second,
81           lat.latitudeDegree, lon.lonitudeDegree, altitude, temp, press, baroAltitude,
82           acc.x, acc.y, acc.z, gyr.x, gyr.y, gyr.z, mag.x, mag.y, mag.z,
83           uvIndex, cpm, nSv, uSv, sats, sog, cog, eul.head, eul.roll, eul.pitch);
84  return String(buffer);
85}
86
87void setup() {
88  Serial.begin(115200);
89
90  while (!gnss.begin()) {
91    DEBUG_PRINT("GNSS: No Devices!");
92    delay(100);
93  }
94  gnss.enablePower();
95  gnss.setGnss(eGPS_BeiDou);
96  gnss.setRgbOn();
97  DEBUG_PRINT("GNSS Initialized");
98
99  bno.reset();
100  while (bno.begin() != BNO::eStatusOK) {
101    DEBUG_PRINT("BNO: Initialization failed");
102    delay(100);
103  }
104  DEBUG_PRINT("BNO Initialized");
105
106  bmp.reset();
107  while (bmp.begin() != BMP::eStatusOK) {
108    DEBUG_PRINT("BMP280: Initialization failed");
109    delay(100);
110  }
111  DEBUG_PRINT("BMP280 Initialized");
112
113  geiger.start();
114  DEBUG_PRINT("Geiger Counter Started");
115
116  if (!SD.begin(SD_CS_PIN)) {
117    DEBUG_PRINT("SD Card init failed!");
118    while (1);
119  }
120  DEBUG_PRINT("SD Card Initialized");
121
122  dataFile = SD.open("/hcelenimissiondatafile.csv", FILE_WRITE);
123  if (dataFile) {
124    dataFile.println("Date,Time,Latitude,Longitude,Altitude,Temp,Pressure,BaroAltitude,AccX,AccY,AccZ,GyrX,GyrY,GyrZ,MagX,MagY,MagZ,UVIndex,CPM,nSv/h,uSv/h,Sats,Speed,Heading,EulHead,EulRoll,EulPitch");
125    dataFile.close();
126  } else {
127    DEBUG_PRINT("Error creating data file!");
128  }
129
130  audio8k = SD.open("/audio_8k.raw", FILE_WRITE);
131  if (!audio8k) DEBUG_PRINT("Error creating audio_8k file!");
132  audio12k = SD.open("/audio_12k.raw", FILE_WRITE);
133  if (!audio12k) DEBUG_PRINT("Error creating audio_12k file!");
134  audio16k = SD.open("/audio_16k.raw", FILE_WRITE);
135  if (!audio16k) DEBUG_PRINT("Error creating audio_16k file!");
136
137  nextSampleTime = micros();
138  lastFlushTime = millis();
139  lastLogTime = millis();
140}
141
142void loop() {
143
144  while (micros() < nextSampleTime);
145  nextSampleTime += SAMPLE_PERIOD;
146
147  int micValue = analogRead(MIC_PIN);
148
149  static int sum8k = 0, count8k = 0;
150  static int sum12k = 0, count12k = 0;
151  static int sum16k = 0, count16k = 0;
152
153  sum8k += micValue; count8k++;
154  sum12k += micValue; count12k++;
155  sum16k += micValue; count16k++;
156
157  if (count16k == 3) {
158    int avg = sum16k / 3;
159    uint8_t sample = map(avg, 0, 4095, 0, 255);
160    if (audio16k) audio16k.write(sample);
161    sum16k = 0; count16k = 0;
162  }
163
164  if (count12k == 4) {
165    int avg = sum12k / 4;
166    uint8_t sample = map(avg, 0, 4095, 0, 255);
167    if (audio12k) audio12k.write(sample);
168    sum12k = 0; count12k = 0;
169  }
170
171  if (count8k == 6) {
172    int avg = sum8k / 6;
173    uint8_t sample = map(avg, 0, 4095, 0, 255);
174    if (audio8k) audio8k.write(sample);
175    sum8k = 0; count8k = 0;
176  }
177
178  unsigned long currentMillis = millis();
179  if (currentMillis - lastFlushTime >= FLUSH_INTERVAL) {
180    if (audio8k) audio8k.flush();
181    if (audio12k) audio12k.flush();
182    if (audio16k) audio16k.flush();
183    lastFlushTime = currentMillis;
184  }
185
186  if (currentMillis - lastLogTime >= LOG_INTERVAL) {
187    lastLogTime = currentMillis;
188
189    sTim_t utc = gnss.getUTC();
190    sTim_t date = gnss.getDate();
191    sLonLat_t lat = gnss.getLat();
192    sLonLat_t lon = gnss.getLon();
193    double altitude = gnss.getAlt();
194    float temp = bmp.getTemperature();
195    uint32_t press = bmp.getPressure();
196    float baroAltitude = bmp.calAltitude(SEA_LEVEL_PRESSURE, press);
197    BNO::sAxisAnalog_t acc = bno.getAxis(BNO::eAxisAcc);
198    BNO::sAxisAnalog_t gyr = bno.getAxis(BNO::eAxisGyr);
199    BNO::sAxisAnalog_t mag = bno.getAxis(BNO::eAxisMag);
200    int analogValue = analogRead(UV_SENSOR_PIN);
201    float uvIndex = (analogValue >= 20) ? min(0.05 * analogValue - 1.0, 11.0) : 0;
202    int cpm = geiger.getCPM();
203    float nSv = geiger.getnSvh();
204    float uSv = geiger.getuSvh();
205    uint8_t sats = gnss.getNumSatUsed();
206    double sog = gnss.getSog();
207    double cog = gnss.getCog();
208    BNO::sEulAnalog_t eul = bno.getEul();
209
210    String csvData = formatCSVData(date, utc, lat, lon, altitude, temp, press, baroAltitude, acc, gyr, mag, uvIndex, cpm, nSv, uSv, sats, sog, cog, eul);
211    dataFile = SD.open("/hcelenimissiondatafile.csv", FILE_APPEND);
212    if (dataFile) {
213      dataFile.println(csvData);
214      dataFile.close();
215    } else {
216      DEBUG_PRINT("Error writing to data file!");
217    }
218
219    float accTotal = sqrt(acc.x * acc.x + acc.y * acc.y + acc.z * acc.z);
220
221    if (!liftOffDetected && accTotal > 1.5) {
222      logAlert("LiftOff Detected", utc);
223      liftOffDetected = true;
224    }
225
226    if (press > maxPressure) {
227      maxPressure = press;
228    } else if (!maxQLogged && press < maxPressure * 0.98) {
229      logAlert("MaxQ Reached", utc);
230      maxQLogged = true;
231    }
232    if (!microgravityLogged && accTotal < 1.0) {
233      logAlert("Microgravity Detected", utc);
234      microgravityLogged = true;
235    }
236    if (!tropopauseLogged && altitude > 11000) {
237      logAlert("Tropopause Entered", utc);
238      tropopauseLogged = true;
239    }
240    if (!stratosphereLogged && altitude > 20000) {
241      logAlert("Stratosphere Entered", utc);
242      stratosphereLogged = true;
243    }
244  }
245}