Bluetooth LE Rocket Telemetry System Using PIC32 BZ2 MCUs

Real-time wireless sensor telemetry using the PIC32 BZ2 family, with pressure, temperature and three-axis acceleration displayed through a Python desktop dashboard over Bluetooth LE or serial.

Engineering demonstration and development reference for real-time wireless sensor telemetry. Validate the complete hardware, firmware, radio and mechanical system before use in any field test. This project is not a certified flight-control or safety system.

Table of Contents

• Overview
• System Architecture
• Hardware and Software
• Repository Organization
• Telemetry Data Format
• Firmware Setup
• Desktop Dashboard Setup
• Running the Demonstration
• Troubleshooting
• Frequently Asked Questions
• References

Overview

The embedded application uses the PIC32 BZ2 family to acquire pressure and temperature data from an MPL3115A2 and three-axis acceleration data from an FXLS8974. The demonstrated hardware uses the WBZ451 Curiosity Development Board. Sensor data is formatted by the firmware and made available through a Bluetooth LE transparent data service or a serial connection.

The Python desktop dashboard receives the sensor data, displays a raw-data view and real-time charts, calculates altitude from pressure and temperature, tracks peak altitude, and records measurements to CSV. The dashboard is primarily validated on Windows. macOS and Linux may also be supported, but they have not been formally validated for this project.

The PIC32 BZ2 family is also available in a high-output-power variant for applications that require longer-range wireless measurements. The family supports 2M PHY for higher-throughput operation and LE Coded PHY for extended-range operation.

Key Capabilities

• Pressure and temperature acquisition using the MPL3115A2
• Three-axis acceleration acquisition using the FXLS8974
• Bluetooth LE and serial telemetry transport
• Live raw-data monitoring
• Five-channel strip charts for pressure, temperature, AX, AY and AZ
• A 200-sample rolling chart window
• Configurable chart ranges and Auto Range scaling
• Altitude calculation from pressure and temperature
• Launch-site baseline capture and peak-altitude tracking
• Timestamped CSV data logging without overwriting earlier logs
• Hardware-independent Demo Mode with a simulated 20-second flight profile

System Architecture

Hardware and Software

Hardware Components

Component	Part / Platform	Role
Wireless MCU development board	WBZ451 Curiosity Development Board	Runs the PIC32 BZ2 firmware, reads the sensors and provides Bluetooth LE or serial telemetry
Pressure and temperature sensor	MPL3115A2, I2C address 0x60	Measures barometric pressure and temperature
Three-axis accelerometer	FXLS8974, I2C address 0x18	Measures acceleration on the X, Y and Z axes; configured for a ±2 g range and 12.5 Hz output data rate
I2C connection	Shared sensor bus	Connects both sensors to the development board; requires appropriate power, ground, wiring and pull-ups
Host computer	Windows PC primarily; macOS or Linux potentially supported	Runs the Python desktop dashboard
Bluetooth adapter	Bluetooth 4.0 or later	Provides Bluetooth LE connectivity when the host does not include a compatible adapter
Serial interface	Compatible USB-to-UART bridge, when required	Provides the wired telemetry connection at 115200 baud
Programming connection	USB	Connects the development board to the development host

The table below lists the I2C connections between the WBZ451 Curiosity Development Board and the two sensors. Confirm the exact pin numbers against the WBZ451 Curiosity Board schematic and the firmware I2C peripheral configuration before wiring.

Signal	WBZ451 Curiosity Pin	MPL3115A2	FXLS8974	Notes
3.3 V	3.3 V supply	VDD (pin 8)	VDD (pin 1)	Both sensors require a 3.3 V supply
GND	GND	GND (pin 5)	GND (pin 8)	Common ground
SCL	I2C clock (verify pin)	SCL (pin 3)	SCL (pin 2)	4.7 kΩ pull-up to 3.3 V required
SDA	I2C data (verify pin)	SDA (pin 4)	SDA (pin 3)	4.7 kΩ pull-up to 3.3 V required
INT	GPIO (optional)	INT1 (pin 6)	INT1 (pin 5)	Interrupt output; leave unconnected if polling is used

Both sensors share the same I2C bus. The MPL3115A2 uses address 0x60 and the FXLS8974 uses address 0x18. Confirm the pull-up resistor values against the actual bus capacitance and clock frequency used in the firmware.

At startup, the firmware verifies both sensors through their identity registers. The expected identity value is 0xC4 for the MPL3115A2 and 0x86 or 0x84 for the FXLS8974. If either sensor is not detected, the firmware reports the failure and stops sensor polling gracefully.

Firmware Software Stack

Component	Details
Language	C
Framework	MPLAB Harmony 3
RTOS	FreeRTOS
IDE	MPLAB X IDE
Compiler	XC32
Target family	PIC32 BZ2
Demonstrated board	WBZ451 Curiosity Development Board

Install tool, device-pack and Harmony component versions that match the firmware project configuration.

Desktop Software Stack

Component	Details
Language	Python 3.10 or later
GUI	Tkinter
Charts	Matplotlib
Bluetooth LE	Bleak
Serial	pySerial
Image support	Pillow dependency status pending reviewer confirmation
Packaging	An included app.spec file may support creating a standalone Windows executable; this workflow has not yet been confirmed for the current project

Desktop Dashboard

Feature	Description
Raw-data view	Displays decoded telemetry frames as they are received
Five-channel strip chart	Displays pressure, temperature and three-axis acceleration using a 200-sample rolling window
Configurable chart ranges	Supports manual Y-axis range settings
Auto Range	Automatically scales the chart Y-axis based on the data range
Calculated altitude	Derives altitude from pressure and temperature; the detailed equation is not included in this README
Launch-site baseline	Capture Start establishes the launch-site baseline used to display relative altitude
Peak-altitude tracking	Displays the highest calculated relative altitude observed during the run
CSV logging	Records timestamp, pressure, temperature, acceleration and altitude to a new timestamped CSV file for each logging session
Demo Mode	Runs a simulated 20-second ascent, apogee and descent profile without hardware

Python desktop dashboard showing live telemetry data.

Repository Organization

Bluetooth-LE-Rocket-Telemetry-System-Using-PIC32-BZ-MCUs/
|
|-- Rocket_Telemetry/
|   |-- Rocket_Telemetry.X/       MPLAB X firmware project
|   |-- application source        Sensor initialization and application logic
|   |-- Bluetooth LE service code Transparent data-service implementation
|   `-- Harmony configuration     Generated Harmony and FreeRTOS configuration
|
|-- Rocket_Telemetry_GUI/
|   |-- app.py                    Desktop dashboard entry point
|   |-- requirements.txt          Python dependencies
|   |-- app.spec                  Potential PyInstaller packaging specification
|   `-- images and application icons
|
`-- Images/                       README and project images

Telemetry Data Format

The dashboard expects five comma-separated floating-point values in this order:

P,T,AX,AY,AZ

Example values:

101.325,24.500,0.010,-0.020,1.002

Field	Measurement	Unit	Example
P	Pressure	kPa	101.325
T	Temperature	°C	24.500
AX	X-axis acceleration	g	0.010
AY	Y-axis acceleration	g	-0.020
AZ	Z-axis acceleration	g	1.002

The five values are enclosed by frame delimiters before transmission. The exact delimiters and line-ending byte sequence remain subject to source-level verification. The dashboard buffers incoming data and ignores incomplete or malformed frames until a complete valid frame is available.

CSV logs use these columns:

Timestamp, P_kPa, T_degC, AX_g, AY_g, AZ_g, Altitude_m

The timestamp format and time basis are intentionally not specified here.

Firmware Setup

Prerequisites

• MPLAB X IDE
• XC32 compiler
• MPLAB Code Configurator and MPLAB Harmony 3 wireless packages that match the firmware project configuration
• PIC32 BZ2 device pack that matches the firmware project configuration
• WBZ451 Curiosity Development Board
• MPL3115A2 and FXLS8974 sensor connections
• Supported programming/debugging hardware:
  • On-board debugger/programmer
  • MPLAB PICkit 4
  • MPLAB ICD 5

Build and Program

1. Open Rocket_Telemetry/Rocket_Telemetry.X/ as an existing MPLAB X project.
2. Confirm that the installed device pack, XC32 compiler, MPLAB Code Configurator and Harmony 3 component versions match the project configuration.
3. Confirm the configured I2C bus, sensor power, pull-ups, console instance and Bluetooth advertising configuration.
4. Use Build Project to compile the firmware.
5. Resolve any generated-code version differences before programming the target.
6. If required after MCC or Harmony code generation, apply the documented FreeRTOS idle-hook update so the idle hook calls app_idle_task(). Refer to app_user_edits.c if that file is included in the published project.
7. Program the WBZ451 Curiosity Development Board using Make and Program Device and a supported programmer/debugger.

Verify Telemetry

1. Power the programmed target and verify that both sensors pass startup detection.
2. Confirm that the target advertises as BLE_UART_DEMO for Bluetooth LE operation.
3. For a wired test, connect the serial interface and use 115200 baud.
4. Verify that complete five-value telemetry frames are produced and accepted by the dashboard.

Desktop Dashboard Setup

Prerequisites

• Python 3.10 or later
• Rocket_Telemetry_GUI/requirements.txt
• A Windows PC for the primarily validated configuration
• A Bluetooth 4.0 or later adapter for Bluetooth LE operation, or a compatible serial interface for wired operation

macOS and Linux may be supported but have not been formally validated. On those platforms, substitute python3 for python if required.

A Python virtual environment is optional. It may be used to isolate the dashboard dependencies from other Python projects.

Install Dependencies

Open a terminal in Rocket_Telemetry_GUI/ and run:

python -m pip install -r requirements.txt

The requirements file is expected to install the packages identified in the Desktop Software Stack, including Bleak, Matplotlib and pySerial. Pillow remains pending reviewer confirmation.

If Matplotlib is missing after installation, install it separately as a troubleshooting step:

python -m pip install matplotlib

Launch the Dashboard

python app.py

The desktop dashboard opens.

Connect over Bluetooth LE

1. Select the literal GUI transport option Bluetooth BLE.
2. Select Scan BLE.
3. Choose BLE_UART_DEMO from the discovered devices.
4. Select Connect.

Connect over Serial

1. Connect the compatible serial interface to the WBZ451 hardware.
2. Select the literal GUI transport option COM Port.
3. Select Scan COM.
4. Choose the appropriate COM port.
5. Confirm that the baud rate is set to 115200.
6. Select Connect.

Running the Demonstration

Hardware Demonstration

1. Power and program the WBZ451 Curiosity Development Board.
2. Launch the desktop dashboard.
3. Connect through Bluetooth LE or a serial COM port.
4. Use Raw On/Off, Chart On/Off and Altitude On/Off to open the required views.
5. Allow the sensor readings to stabilize.
6. In the altitude window, select Capture Start to establish the launch-site baseline for relative altitude.
7. Select Start Log to begin CSV recording.
8. Select Stop Log to close the active log safely.

Each logging session creates a new timestamped CSV file and does not overwrite existing logs.

Demo Mode: No Hardware Required

Select Demo Start to run a simulated 20-second ascent, apogee and descent profile without connected hardware. Demo Mode exercises the raw-data view, strip charts, calculated-altitude view and logging workflow.

Expected Results

When the system is operating correctly:

• Complete telemetry frames appear in the raw-data view.
• Pressure, temperature, AX, AY and AZ update in the five-channel strip chart.
• The altitude view displays calculated relative altitude and tracks the peak value after the launch-site baseline is captured.
• Active logging writes a CSV row for each accepted telemetry sample.
• Incomplete or malformed frames are ignored until a complete valid frame is available.

Potential Applications

The demonstrated architecture could be adapted for other sensor-telemetry applications. Additional engineering, validation and application-specific changes would be required.

• Rocket telemetry: Monitor pressure, temperature, acceleration and calculated altitude during development tests.
• Drone and UAV telemetry: Adapt the sensor and transport pipeline for airborne monitoring applications.
• Environmental monitoring: Replace or extend the sensor set for remote environmental measurements.
• Industrial sensor monitoring: Adapt the acquisition pipeline for machinery, equipment or process measurements.
• STEM and engineering education: Use the project to explore embedded firmware, sensor interfaces, Bluetooth LE, serial communication and real-time visualization.

Troubleshooting

Issue	Checks
No sensor data	Verify the MPL3115A2 address 0x60, FXLS8974 address 0x18, I2C wiring, board pin assignments, power, ground, pull-ups and identity-register responses.
COM port not available	Verify the USB connection, serial driver, port permissions and that no other application is using the port.
Bluetooth LE device not found	Confirm that Bluetooth is enabled, the target is powered and advertising as BLE_UART_DEMO, and the operating system allows Bluetooth scanning.
Connected but no data or plots	Confirm that the firmware is producing five numeric values in the expected field order and that complete frames are reaching the dashboard.
Incorrect altitude	Allow pressure and temperature readings to stabilize, then use Capture Start to establish the launch-site baseline.
Build errors after MCC or Harmony generation	Confirm that installed component versions match the project configuration. If required, reapply the documented idle-hook modification and verify app_user_edits.c.

Frequently Asked Questions

Can different sensors be used?
Other sensors may be adaptable, but the required implementation changes depend on the selected sensor and firmware requirements.

Can another Bluetooth LE device be used with the dashboard?
Other Bluetooth LE devices may be adaptable. Compatibility depends on the implemented data service and telemetry format.

What Python version is required?
Python 3.10 or later.

Can the dashboard be packaged as a standalone Windows executable?
The repository includes app.spec, which may support a PyInstaller-based Windows executable. This packaging workflow still requires validation with the current dashboard and Python 3.10 or later.

Can multiple telemetry sessions be logged?
Yes. Multiple logging sessions are supported. See the CSV logging description for file-handling behavior.

Can serial connectivity be used instead of Bluetooth LE?
Yes. The dashboard supports a serial COM-port workflow as an alternative to Bluetooth LE.

References

• PIC32 BZ2 Wireless Microcontrollers
• Microchip Multiprotocol Modules and SoCs
• Microchip Bluetooth Low Energy Products
• Python

© 2026 Microchip Technology Inc. and its subsidiaries. Firmware source files are subject to Microchip's standard software license. See individual source file headers for full license text.