On Board Computer
OBC Overview
The On-Board Computer (OBC) Command and Data Handling (CDH) is a system of software and hardware connections that enable the collection and storage of the satellite’s health telemetry data and mission specific payload data. The OBC-CDH is developed with C, identical in non-mission specific operation scenario to the previous satellites developed in the BIRDS series but different in software implementation as it inherits base code and hardware from the Kyutech Kitsune line of satellites.
Interface Design
The OBC/EPS board assembly employs four primary microcontrollers: MAIN PIC (PIC18F67J94 – command scheduling and execution), COM PIC (PIC18F67J94 – interface to UHF transceivers and ground link), RESET PIC (PIC18F67J94 – power line control and system resets), and Mission Boss PIC (power DIO switching for mission boards). A START PIC (PIC16F1789) provides redundancy for the RESET PIC and initiates power-up if the RESET PIC is unavailable. The MAIN PIC issues commands to the Mission Boss and mission boards via the CPLD. The Mission Boss and CPLD reside on the backplane board (external to the OBC/EPS board).
The OBC board mates to the backplane using one 50-pin and two 4-pin board-to-board connectors, polarized and keyed. The design and manufacture of the printed circuit board is outsource to the Sagami Tsushin company.
Testing
As the OBC interfaces with all core subsystems and mission components, frequent functional testing is required whenever changes are made; whether on the OBC itself or on any connected subsystem.
Similar tests are conducted across all development stages, from the Breadboard Model (BBM) to the Flight Model (FM), with variations based on factors such as data volume, timing adjustments, and command updates.
25
internal interfaces*
4
redundancy systems*
BBM> FM
tested across all models*