The Altimeter Stick is currently a work in progress. It is designed to be an open-source altimeter board for model rockets. The design was inspired by the Altimeter One originally and recently by the LeoStick (mainly the size/shape). Having built/launched model rockets, I always wondered just how high the rocket flew. Sure, I could use one of those altitude calculators, but I thought I could do better than that.
One aspect of the AltStick that I would consider novel would be the power source: a supercapacitor. Most other altimeters are physically larger because they have to accommodate a battery pack, whether rechargeable or not. The AltStick instead uses very low-power electronics powered by a supercap. This design allows for a smaller size, lighter weight, faster charge time, and nearly unlimited charge cycles. Here are some more design specifications:
- Processor: ATmega328P at 12MHz @ 3.3V
- Power Source: 0.47F Supercapacitor @ 5V
- Interface: USB for charge and data downloading
- Sensors: 3-Axis accelerometer and digital altimeter/pressure sensor
- Sensor Range: +/- 24G acceleration (detects rocket launch and flight profile), >35,000′ altitude
- Piezo buzzer for beeping out altitude and for audible rocket recovery assistance
- RGB LED for status/altitude indication
- ISP header area for programming
- Hole for hook/shock cord mounting
With its diminutive size and weight, the AltStick can be used in small rockets where larger altimeters would simply not fit or would significantly unbalance the rocket. Simply charge (takes about 1 minute), connect to rocket, press set button to zero the altitude to the ground level, and launch. The AltStick will not only measure the peak altitude but also acceleration data. During recovery, listen for the beeps coming from the on-board speaker to help locate the downed rocket. One recovered, press the set button again to beep out or flash out the altitude on the piezo buzzer/RGB LED. Alternatively, the AltStick can download flight data via USB – just pop it in to your laptop to charge it up again, open a text document, and push the button – the AltStick will emulate a keyboard and begin typing out the values stored in its EEPROM.
The USB interface is based on V-USB software for emulating USB in software on non-USB AVR devices. The board can be programmed directly from the Arduino IDE and/or AVRDUDE via the USBasp bootloader. The USB port is also used for charging the supercapacitor, with circuitry included to indicate (LED) when the capacitor is charged up to 5V.
Hardware and software design files can be found on GitHub.