The Gadget
Project Brief
The goal is to create a scientific sampling & diagnostic machine, PDA-esque device and generally cool gizmo in a small, preferably wearable form factor.
Parts
| Main Components | Cost | Notes | ||||
|---|---|---|---|---|---|---|
| Core | Gumstix Overo Fire | $220USD | ||||
| Main Board | Custom PCB (based on Gumstix Chestnut43) | |||||
| FPGA | Co-processor Live data manipulation |
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| 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 | |||||
Progress
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.