Tanduino is an Arduino based project aimed to mimic the analog "tandem" inclinometer + compass.
- Power the device with a DC 3.3V to 9V battery.
- Turn on and off the device with the rocking switch.
- Push the temporary button to start the capturing procedure, you will hear a short chirp, hold the device as stable as possible. A second short chirp will be emitted once satisfactory values are read and the laser will go off. If you hear a long chirp push the temporary button again and try to hold the device more steadily.
- Maintain the temporary button pushed during more than 2s to enter in raw mode (for calibration purposes).
- When the laser diode is on don't look at it directly in the eye.
- The backlight level can be adjusted by rotating the 10KΩ trimmer resistor with a screwdriver.
- The laser power can be adjusted by rotating the 10Ω trimmer resistor with a screwdriver.
The compass is tilt compensated by the accelerometer.
The device must be recalibrated each time the hardware design is modified. Particularly if you decide to use a different battery format (4xAA instead of 1x9V for instance).
- Heading precision: ±0.1º
- Pitch precision: ±0.1º
- Power consumption*:
- hold state: 41mW
- unhold state: 149mW
*Measured with the lowest backlight level and a regular laser power at 20ºC.
After any hardware change (PCB, enclosure, battery etc.), the magnetometer needs to be calibrated. This tutorial is a good start:
Advanced hard and soft iron magnetometer calibration for dummies
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- Adafruit Sensor library
- Adafruit ADXL345 library
- Adafruit HMC5883 Unified library
- Adafruit GFX library
- Adafruit PCD8544 Nokia 5110 LCD library
- Arduino Pro Mini ATmega328 8MHz 3.3V
- Triple Axis Digital Compass HMC5883L
- Triple Axis Accelerometer ADXL345
- 84*48 LCD Display PCD8544
- 5mW 650nm 3V red laser diode
- Rocker on/off button
- Temporary push button
- 10kΩ resistor and 100nF ceramic capacitor for push button debouncing
- 470kΩ and 1MΩ resistors to divide battery voltage sensing
- 10kΩ trimmer resistor to adjust display's backlight
- 10Ω trimmer resistor to adjust laser power
- LT1521 3.3V 300mA voltage regulator and 1µF electrolitic capacitor
- Piezo flat speaker
- Autotransformer (boost piezo voltage)