RaspberryPi Pico support (#152)

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## Description of Problem
After the loss of multiple Teensy4.1s, we've been looking at some more
affordable alternatives for Catalyst-2. Current candidates include the
ProMicro and RaspberryPi Pico. These boards have slightly different
pinouts and chip architectures than the Teensy, so some changes will
need to be made to the firmware to support them.

## Solution
- Added a PlatformIO `env` for the RaspberryPi Pico
- After migrating some chip settings to a central settings file, a build
flag was added to the `pico` env to separate settings for different
architectures.
- Settings for the RaspberryPi Pico were added to support a different
pinout and reduced RAM.

**A Raspberry Pi Pico should now be a drop-in replacement for the Teensy
in Catalyst-2**

main/bmp_altimeter.h

@@ -22,7 +22,7 @@ bmpReading getBMP()
 {
   bmpReading sample;
   if (!bmp.performReading()) {
-    Serial1.println("Failed to perform BMP388 reading.");
+    XBeeSerial.println("Failed to perform BMP388 reading.");
     return sample;
   }
   //sample.temp = bmp.temperature;          // Temperature in Celcius
@@ -49,10 +49,10 @@ void setGroundLevelPressure() { //Reads bmp data and sets ground lvl pressure
  */
 void setupBMP()
 {
-  Serial1.print("Setting up BMP388... ");
+  XBeeSerial.print("Setting up BMP388... ");
   delay(3000);
   if (!bmp.begin_SPI(BMP_CS)) {   // hardware I2C mode, can pass in address & alt Wire
-    Serial1.println("could not find a valid BMP388 sensor, check wiring!");
+    XBeeSerial.println("could not find a valid BMP388 sensor, check wiring!");
     return;
   }
 
@@ -65,9 +65,9 @@ void setupBMP()
     getBMP();
   bmpReading sample = getBMP();
   if(sample.altitude != 0)
-    Serial1.println("BMP setup successful.");
+    XBeeSerial.println("BMP setup successful.");
   else
-    Serial1.println("BMP setup failed, check wiring or pin settings.");
+    XBeeSerial.println("BMP setup failed, check wiring or pin settings.");
   delay(2000);
   setGroundLevelPressure();
 }

main/data.h

@@ -7,7 +7,12 @@
 #include "utils.h"
 #include <SD.h>
 
+#ifndef PICO
 const int CS_SD = BUILTIN_SDCARD;
+#else
+const int CS_SD = 15;
+#endif // PICO
+
 char filename[50];
 RingQueue<imuReading> imuQueue;
 RingQueue<bmpReading> bmpQueue;
@@ -23,18 +28,18 @@ RingQueue<gpsReading> gpsQueue;
 void transmitData(double altitude, gpsReading gps, char phase)
 {
   //phase packet
-  Serial1.print("0 ");
-  Serial1.println(phase); //0: ONPAD, 1: ASCENDING, 2: DESCENDING, 3: POST_FLIGHT
+  XBeeSerial.print("0 ");
+  XBeeSerial.println(phase); //0: ONPAD, 1: ASCENDING, 2: DESCENDING, 3: POST_FLIGHT
 
   //altitude packet
-  Serial1.print("1 ");
-  Serial1.println(altitude,1);
+  XBeeSerial.print("1 ");
+  XBeeSerial.println(altitude,1);
 
   //gps packet
-  Serial1.print("3 ");
-  Serial1.print(gps.latitude, 4);
-  Serial1.print(" ");
-  Serial1.println(gps.longitude, 4);
+  XBeeSerial.print("3 ");
+  XBeeSerial.print(gps.latitude, 4);
+  XBeeSerial.print(" ");
+  XBeeSerial.println(gps.longitude, 4);
 }
 
 /**
@@ -46,21 +51,22 @@ void transmitData(double altitude, gpsReading gps, char phase)
  */
 void setupSD(String date){
   if (!SD.begin(CS_SD)){
-    Serial1.println("MicroSD card: failed or not present");
+    XBeeSerial.println("MicroSD card: failed or not present");
     return;
   }
   else
-    Serial1.println("MicroSD card: successful");
+    XBeeSerial.println("MicroSD card: successful");
   String filestart = "Catalyst2-";
-  filestart.concat(date).concat(".csv");
+  filestart.concat(date);
+  filestart.concat(".csv");
   filestart.toCharArray(filename, 50);
   File dataFile = SD.open(filename, FILE_WRITE);
   if (dataFile) {
     dataFile.println("Time(us),Altitude(m),Latitude,Longitude,GyroX,GyroY,GyroZ,AccelX,AccelY,AccelZ,AttitudeX,AttitudeY,AttitudeZ,state");
     dataFile.close();
   }
   else {
-    Serial1.println("MicroSD card: error opening file");
+    XBeeSerial.println("MicroSD card: error opening file");
   }
 }
 
@@ -108,7 +114,7 @@ void recordData(gpsReading sample, bool prelaunch){
 void backupToSD(){
   File dataFile = SD.open(filename, FILE_WRITE);
   if(!dataFile){
-    Serial1.println("error opening datalog");
+    XBeeSerial.println("error opening datalog");
     return;
   }
   while(!imuQueue.isEmpty()){

main/gps.h

@@ -19,7 +19,7 @@ Adafruit_GPS GPS(&GPSSerial);
  */
 String setupGPS()
 {
-  Serial1.println("Setting up GPS...");
+  XBeeSerial.println("Setting up GPS...");
   unsigned int startTime = millis();
   // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
   GPS.begin(9600);                   // 9600 is the default baud rate
@@ -54,29 +54,29 @@ String setupGPS()
       timer = millis() + 10000;
       int minutes = (timer - startTime)/60000;
       int secs = ((timer - startTime) / 1000) % 60;
-      Serial1.print("Acquiring GPS signal... Time elapsed: ");
-      Serial1.print(minutes);//minutes
-      Serial1.print(":");
+      XBeeSerial.print("Acquiring GPS signal... Time elapsed: ");
+      XBeeSerial.print(minutes);//minutes
+      XBeeSerial.print(":");
       if(secs < 10)
-        Serial1.print("0");
-      Serial1.println(secs);//seconds
+        XBeeSerial.print("0");
+      XBeeSerial.println(secs);//seconds
     }
     if(millis() - startTime > GPS_WAIT_TIME * 1000){
-      Serial1.println("CAUTION!!! GPS timeout: Progressing with no GPS signal");
+      XBeeSerial.println("CAUTION!!! GPS timeout: Progressing with no GPS signal");
       return ERR_NO_GPS;
     }
   }
-  Serial1.println("GPS signal acquired");
+  XBeeSerial.println("GPS signal acquired");
   uint8_t hour = GPS.hour;
   uint8_t minute = GPS.minute;
   uint8_t year = GPS.year;
   uint8_t month = GPS.month;
   uint8_t day = GPS.day;
   uint8_t yearPrefix = 20;
-  
-  String date = String(yearPrefix).concat(year).concat('-').concat(month).concat('-').concat(day).concat("--").concat(hour).concat('-').concat(minute);
-  Serial1.print("Date: ");
-  Serial1.println(date);
+
+  String date = String(yearPrefix) + String(year) + '-' + String(month) + '-' + String(day) + "--"+ String(hour) + '-' + String(minute);
+  XBeeSerial.print("Date: ");
+  XBeeSerial.println(date);
   return date;
 }
 

main/gy521_imu.h

@@ -57,7 +57,7 @@ imuReading getIMU()
  * Verify that the connection is operating properly by taking a sample.
  */
 void setupIMU(){ 
-  Serial1.print("Setting up IMU... ");
+  XBeeSerial.print("Setting up IMU... ");
 
   Wire.beginTransmission(MPU);  //This is the I2C address of the MPU (b1101000/b1101001 for AC0 low/high datasheet sec. 9.2)
   Wire.write(0x6B);             //Accessing the register 6B - Power Management (Sec. 4.28)
@@ -78,28 +78,28 @@ void setupIMU(){
   imuReading sample = getIMU(); // Reads 1 sample of data from IMU.
 
   if(sample.accel.x != 0 || sample.accel.y != 0 || sample.accel.z != 0)
-    Serial1.println("IMU setup successful.");
+    XBeeSerial.println("IMU setup successful.");
   else{
-    Serial1.println("Setup failed, did not read acceleration values from IMU.");
+    XBeeSerial.println("Setup failed, did not read acceleration values from IMU.");
   } 
 
-Serial1.print("X Acceleration: ");
-Serial1.println(sample.accel.x);
+XBeeSerial.print("X Acceleration: ");
+XBeeSerial.println(sample.accel.x);
 delay(1000);
-Serial1.print("Y Acceleration: ");
-Serial1.println(sample.accel.y);
+XBeeSerial.print("Y Acceleration: ");
+XBeeSerial.println(sample.accel.y);
 delay(1000);
-Serial1.print("Z Acceleration: ");
-Serial1.println(sample.accel.z);
+XBeeSerial.print("Z Acceleration: ");
+XBeeSerial.println(sample.accel.z);
 delay(1000);
-Serial1.print("X Gyro: ");
-Serial1.println(sample.gyro.x);
+XBeeSerial.print("X Gyro: ");
+XBeeSerial.println(sample.gyro.x);
 delay(1000);
-Serial1.print("Y Gyro: ");
-Serial1.println(sample.gyro.y);
+XBeeSerial.print("Y Gyro: ");
+XBeeSerial.println(sample.gyro.y);
 delay(1000);
-Serial1.print("Z Gyro: ");
-Serial1.println(sample.gyro.z);
+XBeeSerial.print("Z Gyro: ");
+XBeeSerial.println(sample.gyro.z);
 delay(1000);
 
 }

main/main.ino

@@ -15,14 +15,14 @@ Attitude attitude;
 
 void setup()
 {
-  Serial1.begin(115200);      // xBee baudrate: 115200, 9600
-  Serial1.print("\n\n\n");
+  XBeeSerial.begin(115200);      // xBee baudrate: 115200, 9600
+  XBeeSerial.print("\n\n\n");
 
   pinMode(BUZZER_PIN, OUTPUT);    // Set buzzer pin as an output
   for(int i = 0; i < 5; i++)  // Play 5 beeps
   {
     tone(BUZZER_PIN, 1000);       // Send 1KHz sound signal...
-    Serial1.println("beep!");
+    XBeeSerial.println("beep!");
     delay(1000);              // ...for 1 sec
     noTone(BUZZER_PIN);           // Stop sound...
     delay(1000);              // ...for 1sec
@@ -108,13 +108,13 @@ flightPhase runOnPad(uint32_t tick){
     transmitData(lastBmp.altitude, lastGps, '0');
   }
   if(tick % 1000 == 3 && tick < 30000){
-    Serial1.print("Calibrating IMU... time remaining: ");
-    Serial1.print((30000 - tick)/6000);
-    Serial1.print(":");
+    XBeeSerial.print("Calibrating IMU... time remaining: ");
+    XBeeSerial.print((30000 - tick)/6000);
+    XBeeSerial.print(":");
     int seconds = ((30000 - tick)/100) % 60;
     if(seconds < 10)
-      Serial1.print("0");
-    Serial1.println(seconds);
+      XBeeSerial.print("0");
+    XBeeSerial.println(seconds);
   }
   if(hasLaunched)
     return ASCENDING;

main/settings.h

@@ -16,10 +16,16 @@ constexpr uint32_t TICK_TIME_ASCENDING = 10000;
 constexpr uint32_t TICK_TIME_DESCENDING = 50000;
 constexpr uint32_t TICK_TIME_POST_FLIGHT = 1000000;
 
-constexpr uint32_t RING_QUEUE_LENGTH = 3000;//each 100 elements is 1 seconds of data at 100hz
-
 constexpr uint32_t GPS_WAIT_TIME = 300; //number of seconds to wait for GPS to acquire signal before moving on
 
 constexpr int BMP_CS = 10; //SPI chipSelect of bmp altimeter
+#ifdef PICO
+#define GPSSerial Serial1 //Hardware Serial Location of GPS
+#define XBeeSerial Serial //Hardware Serial Location of XBee
+constexpr uint32_t RING_QUEUE_LENGTH = 1000;//each 100 elements is 1 seconds of data at 100hz
+#else
+#define XBeeSerial Serial1 //Hardware Serial Location of XBee
 #define GPSSerial Serial2 //Hardware Serial Location of GPS
+constexpr uint32_t RING_QUEUE_LENGTH = 3000;//each 100 elements is 1 seconds of data at 100hz
+#endif // PICO
 constexpr int BUZZER_PIN = 33;

platformio.ini

@@ -10,7 +10,7 @@
 
 [platformio]
 src_dir = main
-default_envs = teensy41
+default_envs = teensy41, pico
 
 [env:teensy41]
 platform = teensy
@@ -22,6 +22,18 @@ lib_deps =
 	adafruit/Adafruit GPS Library@^1.7.0
 test_ignore = *
 
+[env:pico]
+platform = raspberrypi
+board = pico
+framework = arduino
+lib_deps = 
+	adafruit/Adafruit BMP3XX Library@^2.1.2
+	adafruit/Adafruit GPS Library@^1.7.0
+	arduino-libraries/SD@1.2.4
+test_ignore = *
+build_flags = 
+	-D PICO
+
 [env:native]
 platform = native
 test_framework = googletest