Flight Software – EPS Module Seyoung Yoon Kyung Hee Univ. at Space Sciences Laboratory University of California, Berkeley

Flight Software Agenda Overview Requirements Design Test Results Development Plan Issues

Overview EPS Module in Hardware CLYDE SPACE 3U-EPS CLYDE SPACE 3U-BATT Solar Array(TBD) EPS Module in Software EPS Source code EPS Header file

Requirements EPS Module Functional Requirements List Requirements item Comments Functional Requirements 5 Providing housekeeping data, processing time, turn off heater, reset I2C, etc Command 11 Command which EPS or BATT provides and EPS Module initialization command Housekeeping data 36 All telemetry which EPS or BATT provides except GND (SYS_004.EPS_Module.xlsx, Feb 03,2010) EPS Module Functional Requirements List Reqmt Description Verification Rationale FSW.EPS-1 Electrical Power System(EPS) module shall provide Voltage, Current, Temperature for EPS board, BATT board and Solar Array TEST EPS and BATT use I2C for control and housekeeping Housekeeping data is transmitted by the TM module FSW.EPS-2 EPS module shall be called periodically by BKG module allowed processing time ≤ 1ms period : 16Hz FSW.EPS-3 EPS module shall turn off the heater for BATT by CMD module Can turn off only, cannot forced on FSW.EPS-4 EPS module shall request Status of EPS or BATT by CMD module Request status register and Return value FSW.EPS-5 EPS module shall reset I2C of EPS or BATT by CMD module In EPS or BATT, Watchdog timer is used for reset

Requirements EPS Module Housekeeping List Mnemonic Bytes Offset Type Units Description MODULE PANEL_Y1_VOLT 2 80 UW V SOLAR PANEL VOLTAGE EPS PANEL_Y1_CURR 96 mA SOLAR PANEL CURRENT PANEL_Y1_TEMP 112 C SOLAR PANEL TEMPERATURE PANEL_X2_VOLT 128 PANEL_X2_CURR 144 PANEL_X2_TEMP 160 PANEL_X1_VOLT 176 PANEL_X1_CURR 192 PANEL_X1_TEMP 208 PANEL_Z1_VOLT 224 PANEL_Z1_CURR 240 PANEL_Z1_TEMP 256 PANEL_Y2_VOLT 272 PANEL_Y2_CURR 288 PANEL_Y2_TEMP 304 PANEL_Z2_VOLT 320 BATT_BUS_CURR 336 Battery Bus Current 5V_BUS_CURRENT 352 5V Bus Current 3.3V_CURR 368 3.3V Bus Current PANEL_Z2_TEMP 384 PANEL_Z2_CURR 400 BATT_DIRECTION 416 Battery Direction BATT BATT_CURR 432 Battery Board Current CELL1_VOLT 448 Battery Cell Voltage BATT_VOLT 464 Battery Voltage BATT_TEMP 480 Battery Temperature BATT1_DIRECTION 496 BATT1_CURR 512 CELL1_VOLT1 528 BATT1_VOLT 544 BATT1_TEMP 560 BATT2_DIRECTION 576 BATT2_CURR 592 CELL1_VOLT2 608 BATT2_VOLT 624 BATT2_TEMP 640 SPARE 4 656 Total Bytes 86 688 EPS Module Housekeeping List

Requirements EPS Module Command List IDENTIFIER Command Description EPS_CHK Request Status Register EPS EPS_PDM_OFF PDM off for short time EPS_PDM_LEN Control of PDM off Pulse EPS_VER Request Firmware version EPS_CHK_PDM Request Status of PDM(includes heater) EPS_I2C_RST I2C Reset in EPS using Watchdog BATT_CHK BATT BATT_VER BATT_HEATER_OFF Battery Heater off BATT_I2C_RST I2C Reset in BATT using Watchdog EPS_INIT Initialization EPS module(in Software) EPS, BATT

Design Flow chart of EPS_CMD() EPS_INIT() I2C Initialization & EPS I2C ON Initialization of global variables, flag and EPS Housekeeping Table EPS_READ_HSK() Called to sample single (1) value and stored If all values are sampled. then return 1. If not, return 0 3. EPS_CMD(cmd) Execute command from CMD module

Design Flow chart of EPS_READ_HSK()

Test Results EPS Housekeeping Table Processing Time Required : 1ms EPS_HSK_BUF[21] BATT_DIRECTION BAT 19 19.000 EPS_HSK_BUF[22] BATT_CURR 909 17.420 mA EPS_HSK_BUF[23] CELL1_VOLT 247 3.671 V EPS_HSK_BUF[24] BATT_VOLT 253 7.415 EPS_HSK_BUF[25] BATT_TEMP 555 20.235 Deg EPS_HSK_BUF[26] BATT1_DIRECTION 1023 1023.000 EPS_HSK_BUF[27] BATT1_CURR 912 7.820 EPS_HSK_BUF[28] CELL1_VOLT1 243 3.689 EPS_HSK_BUF[29] BATT1_VOLT 254 7.406 EPS_HSK_BUF[30] BATT1_TEMP 553 20.561 EPS_HSK_BUF[31] BATT2_DIRECTION EPS_HSK_BUF[32] BATT2_CURR EPS_HSK_BUF[33] CELL1_VOLT2 239 3.706 EPS_HSK_BUF[34] BATT2_VOLT 256 7.387 EPS_HSK_BUF[35] BATT2_TEMP 548 21.376 Array# Mnemonic Src Measured Calculation Unit EPS_HSK_BUF[0] PANEL_Y1_VOLT EPS 808 7.692 V EPS_HSK_BUF[1] PANEL_Y1_CURR 1023 6.533 mA EPS_HSK_BUF[2] PANEL_Y1_TEMP 19 107.043 Deg EPS_HSK_BUF[3] PANEL_X2_VOLT 807 7.280 EPS_HSK_BUF[4] PANEL_X2_CURR 983 21.506 EPS_HSK_BUF[5] PANEL_X2_TEMP EPS_HSK_BUF[6] PANEL_X1_VOLT 809 7.617 EPS_HSK_BUF[7] PANEL_X1_CURR 8.571 EPS_HSK_BUF[8] PANEL_X1_TEMP EPS_HSK_BUF[9] PANEL_Z1_VOLT 560 4.142 EPS_HSK_BUF[10] PANEL_Z1_CURR 29.509 EPS_HSK_BUF[11] PANEL_Z1_TEMP EPS_HSK_BUF[12] PANEL_Y2_VOLT 6.966 EPS_HSK_BUF[13] PANEL_Y2_CURR -1.239 EPS_HSK_BUF[14] PANEL_Y2_TEMP EPS_HSK_BUF[15] PANEL_Z2_VOLT 563 3.577 EPS_HSK_BUF[16] BATT_BUS_CURR 12.238 EPS_HSK_BUF[17] 5V_BUS_CURRENT 972 62.945 EPS_HSK_BUF[18] 3.3V_CURR 942 122.162 EPS_HSK_BUF[19] PANEL_Z2_TEMP 20 106.881 EPS_HSK_BUF[20] PANEL_Z2_CURR 642 201.107 Processing Time Required : 1ms Function PLL(MHz) MIPS I2C(kbps) Processing Time(us) EPS_READ_HSK() 80 40 100 700 200 400 EPS_CMD() 1000 580 Program Memory Data Memory Total Usage 87552 1263 30720 280 1.44% 0.91%

Development Plans Done Phase 1 Phase 2 Phase 3 Phase 4 Definition requirements for EPS module Determine Command & Housekeeping data Making flowchart for the functions(EPS_INIT(), EPS_HSK_READ(), EPS_CMD()) Phase 2 Making a EPS test program(dsPIC33F, I2C Configuration) Coding the functions Phase 3 Test for EPS module with Hardware dsPIC33F + EPS + BATT + USB Power dsPIC33F + EPS + BATT + Power Supply(instead of Solar Array) Checking requirements and function errors Phase 4 Test for EPS module with all FSW modules. Done

Issues How do we reconcile conflict pins (SD_CARD_ON and I2C_ON)? Do we need all commands in Command Table? e.g. PDM (Power Distribution Module) Off, Checking Firmware version of EPS or BATT Measured current direction of stacked batteries is erroneous (?) In base battery board, current direction is correct. But, In stacked batteries, it is wrong. Its ADC value is always 1023(maximum in 10bit ADC) Waiting for the answer about this problem from the ClydeSpace IDENTIFIER Command Description Module EPS_CHK Request Status Register EPS EPS_PDM_OFF PDM off for short time EPS_PDM_LEN Control of PDM off Pulse EPS_VER Request Firmware version EPS_CHK_PDM Request Status of PDM(includes heater) EPS_I2C_RST I2C Reset in EPS using Watchdog BATT_CHK BATT BATT_VER BATT_HEATER_OFF Battery Heater off BATT_I2C_RST I2C Reset in BATT using Watchdog EPS_INIT Initialization EPS module(in Software) EPS, BATT