ESA & SST (ETC) Interface Board Critical Design Review Robert Abiad

1. ESA & SST (ETC) Interface Board • Critical Design Review • Robert Abiad • University of California - Berkeley

2. Overview • Overview of ETC • Interface with particle instruments • Processing of particle data • Passing data back to DCB (main processor)

3. 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

4. Connections Shared board SST_CMD SST 8MHz DCB STLM_REQ STLM_DAT SPIN/32 ETC TLM_DATA ETC_CMD ECMD_GATE POR_L ECMD_DATA ESA SPINPULSE ECMD_CLK SPINCLK ETLM_DATA RESET ETLM_CLK EANA_HSK SANA_HSK

5. 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

6. 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

7. 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

8. Requirements • 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

9. Requirements • 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  

10. 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

11. Electrical Diagram

12. 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

13. Power • Power estimation • Actel 305mW + 2 SRAM (25mW/MHz) 50mW + Transceivers 20mW = 375mW

14. Testing Plan • 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

15. Issues • Difficulty in recognizing data errors • Availability of instruments • Actel reliability