On-Board Computer V.2.x
The On-Board Computer (OBC) version 2 family is in development phase right now.
- STM32F407VGT6 32-bit ARM Cortex-M4F microcontroller, 1 MB Flash, 192 KB RAM
- System Clock: Real Time Clock (RTC)
- 2Mbit SRAM
- UART connection for GPS modul
- CAN controller + CAN transceiver
- DCMI port for integrated camera control
- Micro SD-card slot
- Diagnostic port
- 2×20 pin stackable UPRA-BUS connector
GPS coordinates, altitude and speed was provided by a UBLOX-NEO6M module. This GPS reciever can be configured to flight mode designed for high-altitude operations and has an altitude limit of 50 kms (~32 miles), so we could track the entire flight of the balloon. The UBLOX module communicates with the OBC through NMEA standard. Parsing the proper NMEA messages longitude, latitude, altitude and speed data could be processed. Each GPS NMEA word has time stamp which used for synchronize the system time. Time Sync is needed, because the Real Time Clock (RTC) unit of the OBC produce increasing slip due to the temperature decrease.