Ignitia CanSat Avionics

Drone-drop CanSat flight computer based on RP2040-Zero.

Features

• Drone Drop Mode - Detects freefall and deploys parachute
• Sensors: MPU6050 (IMU), BME280 (barometer), NEO-M8M (GPS)
• Telemetry: NRF UART radio + USB debug
• Actuator: Servo for parachute deployment

Pin Assignments (RP2040-Zero)

Pin	Function	Notes
GP0	NRF TX	UART0 TX to NRF radio
GP1	NRF RX	UART0 RX from NRF radio
GP4	I2C SDA	MPU6050 + BME280
GP5	I2C SCL	MPU6050 + BME280
GP8	GPS TX	UART1 to NEO-M8M
GP9	GPS RX	UART1 from NEO-M8M
GP15	Servo	PWM output
GP16	LED	Status indicator

Pico SDK Setup (Windows)

1. Install Prerequisites

# Install via winget (Windows 11) or download manually
winget install Kitware.CMake
winget install Ninja-build.Ninja
winget install Arm.GnuArmEmbeddedToolchain
winget install Git.Git

Or download manually:

• CMake (add to PATH)
• Arm GNU Toolchain - arm-none-eabi-* version
• Ninja (optional, makes builds faster)
• Git

2. Clone Pico SDK

cd C:\
git clone https://github.com/raspberrypi/pico-sdk.git
cd pico-sdk
git submodule update --init

3. Set Environment Variable

# Permanent (run as Admin)
[System.Environment]::SetEnvironmentVariable('PICO_SDK_PATH', 'C:\pico-sdk', 'User')

# Or for current session only
$env:PICO_SDK_PATH = "C:\pico-sdk"

4. Build the Firmware

cd E:\IGNITION\Ignitia_Avionics
mkdir build
cd build
cmake -G "NMake Makefiles" ..
# OR with Ninja (faster)
cmake -G Ninja ..

# Build
cmake --build .
# OR
ninja

5. Flash to RP2040-Zero

1. Hold BOOTSEL button on RP2040-Zero
2. Connect USB cable
3. Release BOOTSEL - appears as USB drive
4. Copy build/ignitia_avionics.uf2 to the drive
5. Device reboots automatically

Flight Sequence

IDLE ──► ARMED ──► FREEFALL ──► DEPLOYED ──► LANDED
  │        │          │            │           │
  │        │          │            │           └─ Low velocity at ground
  │        │          │            └─ Parachute opened
  │        │          └─ Drop detected (low g / falling)
  │        └─ Attached to drone, waiting for drop
  └─ Power on, calibrating

Commands (USB Serial)

Key	Command	Description
a	Arm	Ready for drop
d	Disarm	Return to idle
t	Test	Test servo
s	Status	Show current state
c	Calibrate	Recalibrate sensors
r	Reset	Full reset
h	Help	Show commands

Telemetry Packet Format

NRF Telemetry (binary)

struct TelemetryPacket {
    uint8_t  header;      // 0xAA
    uint8_t  type;        // 0x01
    uint16_t seq;         // Sequence number
    uint32_t timestamp;   // ms since boot
    uint8_t  state;       // Flight state
    int16_t  altitude;    // decimeters
    int16_t  velocity;    // cm/s
    int16_t  accel;       // milli-g
    int16_t  temperature; // 0.1°C
    uint8_t  gps_sats;
    uint8_t  flags;       // Armed, deployed, etc.
    uint8_t  checksum;    // XOR
};

USB Debug (ASCII)

$T,12345,ARMED,150.5,0.3,1.02,0
$G,28.572900,-80.649000,152,8
$S,12345,DROP DETECTED

Wiring Diagram

                    RP2040-Zero
                   ┌───────────┐
              3V3 ─┤1        22├─ GND
              GND ─┤2        21├─ GP15 ──► Servo Signal
        NRF TX ◄── GP0 ─┤3        20├─ GP14
        NRF RX ──► GP1 ─┤4        19├─ GP13
                  GP2 ─┤5        18├─ GP12
                  GP3 ─┤6        17├─ GP11
    I2C SDA ◄───► GP4 ─┤7        16├─ GP10
    I2C SCL ◄───► GP5 ─┤8        15├─ GP9 ◄── GPS RX
                  GP6 ─┤9        14├─ GP8 ──► GPS TX
                  GP7 ─┤10       13├─ GP16 ──► LED
                 3V3EN─┤11       12├─ GND
                       └───────────┘

    I2C Bus (GP4/GP5):
    ├── MPU6050 (0x68)
    └── BME280 (0x76)
    
    UART0 (GP0/GP1): NRF Radio
    UART1 (GP8/GP9): GPS NEO-M8M

Safety Features

• Deployment delay - 500ms after drop detection
• Safety timeout - Force deploy after 30s from drop
• Altitude check - Don't deploy below 30m
• Redundant detection - Accelerometer + barometer

Development

Run Tests (host)

cd test
gcc -DHOST_TEST test_flight_state.c -o test_flight_state && ./test_flight_state
gcc test_filters.c -lm -o test_filters && ./test_filters

Run SIL Simulation

cd sil
pip install -r ../requirements.txt
python sil_runner.py test_scenarios/nominal_flight.json

License

MIT License - Ignitia Team