Embedded Firmware Development for a Novel CubeSat Gamma-Ray Detector

The Gamma-ray Module (GMOD) is an experiment designed for the detection of gamma-ray bursts in low Earth orbit as the principal scientific payload on a 2-U CubeSat, EIRSAT-1. GMOD comprises a cerium bromide scintillator coupled to silicon photomultipliers which are processed and digitised by a bespoke ASIC. Custom firmware on the GMOD motherboard has been designed, implemented and tested for the MSP430 microprocessor which manages the experiment including readout, storage and configuration of the system. The firmware has been verified in a series of experiments testing the response over a realistic range of input detector trigger frequencies from 50 Hz to 1 kHz for the primary time tagged event (TTE) data. The power consumption and ability of the firmware to successfully receive and transmit the packets to the on-board computer was investigated. The experiment demonstrated less than 1 % loss of packets up to 1 kHz for the standard transfer mode with the power not exceeding 31 mW. The transfer performance and power consumption demonstrated are within the required range of this CubeSat instrument.