QB50 System Requirements Document

CONTENTS1 Introduction ............................................................................................................ 52 Normative and Informative documents ............................................................... 62.1 Normative Documents ................................................................................... 62.2 Informative Documents .................................................................................. 63 Abbreviations ......................................................................................................... 74 Electrical Interfaces ............................................................................................... 74.1 Science Unit Connector Definition ................................................................ 94.1.1 SWITCHED Power Pins .......................................................................... 104.1.2 Grounding ................................................................................................ 104.1.3 Surface Thermal Monitor (STM) Thermistors .......................................... 104.1.4 Surface Thermal Monitor Thermistor Locations ....................................... 114.1.5 Science Unit Thermistor .......................................................................... 114.1.6 Science Unit Serial Interface ................................................................... 114.2 Sun Sensor.................................................................................................... 114.3 EMC requirements ........................................................................................ 114.4 Power Budget ............................................................................................... 125 CubeSat OBC Software Requirements .............................................................. 135.1 Overview of SU Control Strategy ................................................................ 135.2 Data Handling and Control .......................................................................... 135.3 Command & Response Handling ................................................................ 145.3.1 OBC Sending a Command Packet .......................................................... 145.3.2 OBC Error Handling of Science Unit ....................................................... 145.3.3 SU Error Handling: Command Execution Error Handling ........................ 155.3.4 SU Error Handling: Sending a Response Packet ................................... 155.4 Command Packet Structure to Science Unit .............................................. 165.5 Reponses Packet Structure to CubeSat ..................................................... 165.6 Data Rates and Volumes .............................................................................. 175.6.1 Example INMS Operation Scenario ......................................................... 175.7 SU State Transition Diagram ....................................................................... 185.8 OBC Script Commands ................................................................................ 195.9 OBC Script Command Description ............................................................. 195.9.1 OBC and SU Specific Commands ........................................................... 195.9.2 Script TIME Field - @t ............................................................................. 205.9.3 Script Encoder Software Tool .................................................................. 20