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Open Tag3 Manual
Overview
OpenTag3 records motion sensors at 50 Hz, and depth, temperature, light, and speed sensors at 1 Hz to
CSV files. Files are 1 hour long by default. There will be a short gap between files. OpenTag3 supports 32
GB or smaller microSD cards.
OpenTag3 is open source. Software is located at https://github.com/loggerhead-instruments/OpenTag3
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Accelerometer, Gyroscope, Magnetometer (MPU9250): 100 Hz
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Pressure/Temperature (MS5837 or Keller PA7LD): 1 Hz
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RGB light level (ISL29125): 1 Hz
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Burn wire release: controls a FET switch to ground which can be used to corrode a stainless steel
wire in seawater
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Summary of Contents for OpenTag OpenTag3
- Page 1 OpenTag3 records motion sensors at 50 Hz, and depth, temperature, light, and speed sensors at 1 Hz to CSV files. Files are 1 hour long by default. There will be a short gap between files. OpenTag3 supports 32 GB or smaller microSD cards.
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Page 2: Quick Start
The time is set by saving the setup.txt card with a date and time, ejecting the card from the computer, and inserting the card into the OpenTag board. When the time stored on the card occurs, the power switch should be turned on to set the time on the clock. - Page 3 Example setup.txt File (set time to 10 April 2018 at 1 PM; Trigger burn after 400 minutes) // Set Time TM 18-04-10 13:00:00 // Set burn in x minutes BM 400 setup.txt Commands setup.txt should be saved in root of microSD (not in a directory) // Indicate lines that are comments.
- Page 4 Charging The lithium battery can be charged by connecting a microUSB cable to the OpenTag3 and a PC or other charger. When charging the red LED will be on. When charging is complete the LED will turn off. Charging will typically take less than 10 hours.
- Page 5 Burn Wire A burn wire is a corrodible stainless steel wire that can be used to release the AMX from a platform or release suction from suction cups. The recommended wire is from McMaster-Carr (302/304 stainless steel wire 0.01” diameter). https://www.mcmaster.com/ - 6517k61/=17yvpwx The timing of the burn wire start is controlled by the BM command in the setup.txt file.
- Page 6 Depth Sensors and Maximum Depth The OpenTag3 is equipped with one of two types of pressure sensors, each of which has a maximum depth that it can sustain. If the tag could go deeper than 300 m, the air void where the microSD card is located should be filled with mineral oil.
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Page 7: Sensor Calibration
Sensor Calibration All sensors used on OpenTag are digital, in that they have their own analog-to-digital converter. The values stored by OpenTag are calibrated using the calibration values supplied in the technical specification sheets. Example data file: accelX accelY accelZ... - Page 8 Sensor Calculations The IMU data (accelerometer, magnetometer, and gyroscope) and RGB light sensor data are stored as 16-bit integers. They need to be multiplied by a calibration factor to get appropriate units. The pressure data are stored as mBar and a depth calculation is performed assuming saltwater (111.377 mBar/m) and a surface pressure of 1010.0 mBar.
- Page 9 Making a Recording for Gyroscope Calibration Note that when the tag is recording without moving, the gyroscope should have values of 0 degrees/second, but there is typically an offset. Place device in a known orientation for a few seconds when recording starts. Generally a flat surface is a good idea.
- Page 10 Revision History 23 April 2018 Initial Manual 10 | P a g e...
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