By Jeremy Seiden (Mission, Systems, and Test)

I review the final system block diagram (including subsystem block explanations) for the dosimeter/SEU-detector project.

Introduction

Below is the project block diagram that represents the Spring 2016 SPARCCS instrument. The block diagram allows the team and customers to see the function of the instrument board broken down to each of its major subsystems. The diagram also reflects the contents of the board and what systems are interfaced with externally. For the Spring 2016 SPARCCS project, both instruments and support hardware are contained on a single PCB for easy installation to the existing aluminium chassis. Systems not contained on the instrument board can be seen outside of the main diagram block.

Subsystem Explanations

SPARCCS Instrument Board: The overall PCB contains all components for the function of the 2016 SPARCCS Instrument aside from the CD&H (to be club specified) and the 5-volt power supply connection (club defined)

ATMega32U4: This microcontroller chip was selected for its user friendliness, reliability, and built in serial communication features. The two onboard instruments (Geiger-Muller Tube and CMOS Camera) connect to pins on the microcontroller for formatting and data output to CD&H.

uCam-II: (Micro Cam 2) is a small CMOS camera. The camera’s purpose is to allow for the detection of high energy particles that are responsible for charging. The camera unit contains its own processor and communicates via a serial connection with the ATMega 32U4.

Geiger-Muller Tube: (LND 712) This piece of the instrument board is responsible for detecting the presence of ionizing radiation. Supplied by the high voltage DC converter, the tube triggers an interrupt when sufficient current leaves the collecting line of the tube.

RS-422 Transceivers: This module is responsible for the conversion of data to be sent and received via RS-422 protocol.

PC-104 Bus Connector: This connection has been included to standardize the instrument for use inside of a Cube Satellite. This 64-pin connector will allow the board to interface with other parts of the satellite.

Mini USB Port: This port was included on the board to allow for easy bootloading of our operation program.

A05P-5 DC/HVDC Converter: In order to properly energize the Geiger-Muller tube’s central line to an operating voltage of ~500VDC a DC to high voltage DC converter is needed to step the voltage up from our supplied 5VDC.

C&DH: This acronym stands for Command & Data Handling. This subsystem is typically onboard the spacecraft, but is not a part of our instrument. Command and data handling is responsible for the sending and receiving of information across the downlink to earth.