On the left: 10DoF unit with integrated Lithium battery and charger.
On the right: 10DoF unit without battery.
The Smart-Logger connected to the Miniature-Pitot-Tube for true air speed measurement and logging. The small structure and lightweight solution are most interesting for RC-Model users.
Concept
The Smart-Logger is a lightweight, wireless (optional), low-power data-logging with a Real-Time Clock (RTC), integrated 6DoF inertial sensors, a 3-axis magnetometer, thermometer, high-sensitivity barometer, and an auxiliary analog input. It is suitable for both academic research and home use. With a power consumption low enough to last up to a month on a 240mAh LiPo battery, its actual operating time varies based on sensor activity, sampling rates, and data compression settings. The Smart-Logger can function as a data logger or as an real-tome Inertial Measurement Unit (IMU).
Storage Options
2 MB FLASH
4 MB FLASH
8 MB FLASH
Communication
Smart-Logger uses Bluetooth for communication (standard COM profile); an optional BLE version is available.
The Smart-Logger supports:
Real-time telemetry transmission
Log downloads
Configuration of sampling rates, data compression, active sensors, and power settings
Firmware updates
Communication Range
Up to 25m in open areas with a laptop. Range may vary.
Wired version is also available (UART-TTL or UART-USB).
Measurement Modes
Continuous: Configurable sampling rate of 0.05 to 20 Hz
On-Change Detect: Activates only upon sensor change. This saves power and log memory
Data Compression Formats
Raw 16-bit (uncompressed)
Raw 8-bit (Lossy compression by linear down scaling)
MuLaw 16-bit to 8-bit (Lossy compression by logarithmic down scaling)
Operating Modes
OFF (Standby)
Real-time Transmission
Logging
Log Downloading
Real-Time Transmission + Logging
Log Downloading + Logging
Real-Time Transmission + Logging + Log Download
Specifications
Sensor options: Up to 3-axis accelerometers, 3-axis gyros, temperature, barometer, and 3-axis magnetometer.
Auxiliary Analog Input: 0 to 3V, 10-bit resolution (~3mV).
Sampling Period: 30 seconds to 50 milliseconds with 5ms resolution.
Maximum Sampling Rate:
All sensors: 9 Hz
Single sensor: 20 Hz
Dimensions: 30 x 25 x 14 mm
Weight:
10DoF version: 8g (without battery)
3DoF version: 5.5g
Battery: Options of 240mAh (6g) and 350mAh (9.5g).
Battery life: Over one month (with 3 accelerometers at 1 Hz sampling).
Power consumption: 540 µW for typical settings.
Auxiliary Analog Input
The Smart-Logger includes a single analog input capable of measuring internal battery voltage when not connected to a source. It has a ground and 3.3V/100 mA output, suitable for various sensors such as:
Pitot Tube (air velocity)
Load Cell (weight/force)
Remote temperature sensors
Light intensity sensors
Motion sensors
Current/Voltage sensors
Sound intensity sensors
Firmware Specifications
The Smart-Logger operates over the GS-Real-Time-Operating-System with the below key features:
Designed for optimal performance across Microchip's PIC series (8-bit, 16-bit, and 32-bit).
GS-Device-Control-Network Protocols Stack (DCN): Enables point-to-point or half-duplex communication.
GS-System-Monitor-Application (SMA): Provides remote access and monitoring.
GS-Virtual-RPN-Machine (VRM): A virtual processor for executing user-defined scripts or control loops.
User Application
Smart-Logger offers a user-friendly Python-based GUI for operation and configuration.
All measurements were done with active logging and transceiver-OFF
Gyro-meter:
consumes 5µA in sleep mode.
consumes (1.5mA + 0.024mA*Sampling_Rate) when working
Barometer:
Sample time: | 4.5ms| 7.5ms| 13.5ms| 25.5ms |
Barometer: |3.6µA| 6.0µA| 10.8µA| 20.4µA |
Magnetometer: 240µA +0.5µA*Sampling_Rate
The log size can estimated based on the compression type (number of bytes for each sensor result), the sampling rate, and the log time.
Calculation example:
Active sensors: Thermometer + Barometer
Compression: Any type
Sampling rate: 0.1[hz] (every 10[sec])
NVM: 32M[bit] == 4M[byte] == 4*1024*1024[byte]
hours = 4*1024*1024 / (2+3) * (1/0.1) /60 /60 ≈ 1165hour = 97days