The Gadget

The goal is to create a scientific sampling & diagnostic machine, PDA-esque device and generally cool gizmo in a small, preferably wearable form factor.

Main Components Cost Notes
Core Gumstix Overo Fire $220USD
Main Board Custom PCB (based on Gumstix Chestnut43)
FPGA Co-processor
Live data manipulation
Built in Sensors Model # Interface Resolution Sample Rate Cost Notes
Temperature & Humidity DHT11 $9.00AUD
Barometric Pressure SCP1000 SPI 15bit 9Hz $77.98AUD
Infrared Thermometer MLX90614 I2C 10bit $25.24AUD
Magnetic Flux Sensor HMC5843 I2C 12bit x 3 10Hz $20
Accelerometer ADXL345 SPI / I2C 13bit x 3 3.2kHz $17
Gyro ITG-3200 I2C 16bit x 3 8kHz $30
GPS RS232 10Hz
Camera e-CAM32 Camera Port 3.2MP $100 3rd party Gumstix expansion
Pulse Oximeter Gumstix ADC red/IR LED + Phototransistor
Electronic Diagnostics Pack Model # Interface Resolution Sample Rate Cost Notes
ADC Parallel (to FPGA) 100MS/s Oscilloscope features
Fast digital I/O Parallel (to FPGA) Buffer IC on FPGA
Low speed digital I/O MCP23017 I2C
Built in Output Devices Model # Notes Cost
4.3“ LCD
DACs For a signal generator
Line Laser For a 3D scanner
Point Laser For a range finder
3W RGB LED Torch / Flash / Data port
Power Supply Model # Notes Cost
Li-Poly RC car battery With quick-release, firewalls etc. $60
Switched mode power supply module Recom 9-36V in, 5V out $20
current limits / under-voltage trips custom (bullet-proof) BJT latch + fuse

The Gumstix overo-fire and chestnut43 boots from an RC car battery with 5V SMPS and an over-current under-voltage lockout circuit (set to <1A, >9V on the 11.1V input rail, schematics coming soon!)

The Gumstix system consumes about 0.45A at 12V. Far too much for a portable device, but most of that is the LCD back-light.

Oddly, the Gumstix module refuses to connect to a USB device without a USB hub (powered or unpowered) so the gadget will have multiple USB sockets, some populated by internal devices.

An Arduino pro-mini will be used (for now) to control the sensors and output devices. The final version will probably use a low-power micro-controller for data logging, power management and anything an OS isn't required for (whatever I can be bothered hard-coding on a micro) The pro-mini currently collects data from a barometer, humidity sensor and a magnetometer and displays it on a character LCD.

  • projects/thegadget.txt
  • Last modified: 2020/03/12 12:49
  • (external edit)