Desain dan Implementasi On-Board Computer/ On-Board Data Handling (OBDH) pada UGM-SAT

摘要

The engineering model of OBDH for UGM-SAT was designed to control data handling program and tointerface the satellite subsystems to OBDH. The OBDH ’ s based on the Microchip microcontroller PIC16F877A with 20 Mhz clock speed. The system ’ s equipped with four external 24LC512 EEPROM’s with a storage capacity of 256 kB. The external memories ’ re used to store housekeeping information. The system ’ s equipped with a ACS712ELCTR-05B-T current sensor, voltage sensor and LM335Z temperature sensor. The accuracy of the measurements ’re more than 99%. The system ’ s also equipped with IC Real Time Clock (RTC) DS3232M with an internal clock of 32.768 Hz, which ’ s used to synchronize the time between OBDH with other subsystems. The components of OBDH was chosen with industrial standards, small packages and low power. OBDH ’ s designed to operate in environments with extreme temperature conditions. The communication with other subsystems was designed to use I2C-bus. Protocol data for communication between the satellite subsystems have been designed. A Hamming Code( 8,4 ) algorithm has been implemented to protect housekeeping information from being corrupted due to radiatio n . Error detection and correction speed is 1.800 byte/s. The engineering model of OBDH for UGM-SAT have met the standard specifications, and ready for further testing hardware and software.