Rocket Altimeter - AXEtimeter I


My daughter wanted to know how high her model rockets are flying. Perfect project for the PICAXE. I used a Freescale MPL3115A2 pressure sensor for reading the altitude and temperature, a Microchip 24FC512 EEPROM to store the flight data, and an ST M41T62LC6F real time clock to keep track of the flight time. All of this connected to a PICAXE 14M2 using I2C. The power source needed to be light because I wanted the AXEtimeter to fly on even the little rockets in my daughter's fleet, so I chose a super capacitor. Having a rough estimate of power consumption since all of the components are SMD, I only had datasheets and calculators to go by so I chose a Maxwell 5F 2.7V supercap. Charged up to ~2.45V, we can get roughly 7 or 8 flights out of it before it needs to be recharged...which only takes a few minutes. A Microchip MCP16251 sync boost regulator handles voltage duties delivering 2.7V to all the components till the supercap discharges to about 0.8V. Once the flights are recorded, choose "TRANS"mit from the AXEtimeter's menu and all the flight data (elapsed time down to 1/100s, temperature, and altitude) is downloaded over the serial cable to the PC. Checkout my blog (Project website above) for the build, detailed parts overview, sample flight data and charts (in Part 4) and a couple videos (in Part 5). First flight of her little B-6 powered rocket went 105meters :)
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