THEMIS CDR 1 UCB, June 16, 2004 ESA & SST (ETC) Interface Board Critical Design Review Robert Abiad University of California - Berkeley

THEMIS CDR 2 UCB, June 16, 2004 Overview Overview of ETC Interface with particle instruments Processing of particle data Passing data back to DCB (main processor)

THEMIS CDR 3 UCB, June 16, 2004 Connections Instrument and DCB interfaces ESA commanding –ETC acts as translator –ESA & SST data collected –ETC collects data and processes it ESA & SST spin sectoring Other signals –SST commanding from the DCB –ESA & SST analog housekeeping wires to the DCB –SST clock from the DCB

THEMIS CDR 4 UCB, June 16, 2004 Connections DCB ETC SST ESA 8MHz EANA_HSK SANA_HSK ECMD_GATE ECMD_DATA ECMD_CLK ETLM_DATA ETLM_CLK STLM_REQ STLM_DAT TLM_DATA ETC_CMD SST_CMD SPINCLK SPIN/32 Shared board POR_L SPINPULSE RESET

THEMIS CDR 5 UCB, June 16, 2004 Requirements Data production Slow Survey - 13 moments/data type (2 species x 2 instruments) Slow Survey - Reduced angle distribution/data type/Nspins Fast Survey - Full angle distribution/data type/Nspins Burst - Full angle distribution/data type/spin

THEMIS CDR 6 UCB, June 16, 2004 Requirements Moments There are 13 moments calculated for 4 different data types Moments are calculated using an entire spin of data  represents the 32 spin angles  represents elevation angle - 4 for SST and 16 for ESA E represents particle energy -16 for SST and 32 for ESA

THEMIS CDR 7 UCB, June 16, 2004 Requirements Moments (cont.) C is the count of particles at a particular field of view. This data comes from the instruments.  is the solid angle. This value is programmed into a lookup table by the processor. WP is a combined weighting and spacecraft potential correction. This value is calculated in the ETC using lookup tables and the equation: Where V is the spacecraft potential and N=0-3

THEMIS CDR 8 UCB, June 16, 2004 Distributions Purpose –Measure full particle angular distributions with equal solid angle resolution. Polar angle measurements are combined to produce equal solid angle bins and to reduce data volume. Full Distributions –ESA sees 512 fields of view in a spin (32 spin phase x 16 elevation angles). This gets reduced to 88 angle bins. –SST sees 128 fields of view in a spin (32 spin phase x 4 elevation angles). This gets reduced to 64 angle bins. –Solar wind mode gives higher angular resolution Reduced Distributions –For survey data covering more of an orbit due to low bandwidth –ESA and SST data reduced to 8 angle bins. –Electron pitch angle distributions Requirements

THEMIS CDR 9 UCB, June 16, 2004 Distributions (cont.) Burst Distributions –Burst are identical to full distributions in angular and energy makeup, but recorded every spin. All data will be converted from X bits to Y bits using a pseudo square-root compression scheme Use lookup tables to do angle translations Requirements  

THEMIS CDR 10 UCB, June 16, 2004 Status FPGA design completed Individual modules simulated System simulations ongoing Debugging in GSE hardware Timing requirements met in Actel Board testing underway Post-Combiner device utilization: SEQUENTIAL Used: 1743 Total: 2012 (86.63%) COMB Used: 3138 Total: 4024 (77.98%) LOGIC Used: 4881 Total: 6036 (80.86%) (seq+comb) IO w/ Clocks Used: 50 Total: 167 CLOCK Used: 2 Total: 2 QCLK Used: 0 Total: 4 HCLOCK Used: 1 Total: 1

THEMIS CDR 11 UCB, June 16, 2004 Electrical Diagram

THEMIS CDR 12 UCB, June 16, 2004 Processor Requirements Table Loading 30 tables totaling 51 KBytes –4  - computed on board –12 distribution angle lookup tables - loaded from ground –4 exponential lookup tables - in EEPROM –6 energy lookup tables - loaded from ground Commanding 1 spacecraft potential command/spin Less frequent setup commands –Number of spins to collect data –Number of angles data is being binned into Maintaining collected data 13 DMA channels to mass memory Inserting headers into data

THEMIS CDR 13 UCB, June 16, 2004 Power Power estimation Actel 305mW + 2 SRAM (25mW/MHz) 50mW + Transceivers 20mW = 375mW

THEMIS CDR 14 UCB, June 16, 2004 Simulation GSE Design loaded into an Altera part along with a microprocessor allows quick runs with a minimal of support Debugging of design DCB/ETC Need GSE to produce data (ready) Need software to run the DCB Debugging of board and system Testing Plan

THEMIS CDR 15 UCB, June 16, 2004 Issues Difficulty in recognizing data errors Availability of instruments Actel reliability