1. November 27, 2002 RMU-CPU Interface - Version 1.8 RMU - CPU Interface

2. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.3 Changes Added overrun bit to the status word needed a second command status word Added a 1 Hz signal (1PPS) to phase lock the RMU to the 1 Hz timing pulse from the spacecraft Added enable/inhibit for the 1PPS function Added t w (min) for CPU strobes = 250 ns Added definition of science packet

3. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.4 Changes Changed test pattern definitions Resized Little Pulse storage for 15 pulses

4. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.5 Changes Changed definition of bits for Most Significant Byte for Start, Big Pulse and Little Pulse Added Status/Mode Word 3 (programmable fine time circuit reference value - bit definition TBD)

5. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.6 Changes Changed definition of bits for all timestamps (Start, Big Pulse and Little Pulse) Added 4th byte for Start Pulse

6. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.7 Changes Added Status Word 3 Redefined bits in Status Word 2

7. November 27, 2002 RMU-CPU Interface - Version 1.8 Release 1.8 Changes Finalized defs in Status Words 1, 2 and 3

8. November 27, 2002 RMU-CPU Interface - Version 1.8 RMU - CPU SIGNALS RMURMU CPUCPU RUPT FPGAs = SX-S; All drivers low slew, always enabled. Receivers are set to 5V CMOS switching thresholds. Receiving side provides bus hold, 10 k  resistor. RMU may be powered off with CPU powered on. Parity is odd. RMU_DATA[7:0] CPU_DATA[7:0] CPU_ADDR[3:0] CPU_RD CPU_WR CPU_SPARE1 CPU_SPARE0 RMU_SPARE0 RMU_SPARE1 RMU_PARITY 1PPS

9. November 27, 2002 RMU-CPU Interface - Version 1.8 RMU Address Map 0000 READ SCIENCE DATA (FIXED BLOCK, SIZE TBD) 0001 READ/WRITE RANGE GATE START LOW BYTE 0010 READ/WRITE RANGE GATE START MIDDLE BYTE 0011 READ/WRITE RANGE GATE START HIGH BYTE 0100 RESERVED 0101 READ/WRITE RANGE GATE END LOW BYTE 0110 READ/WRITE RANGE GATE END MIDDLE BYTE 0111 READ/WRITE RANGE GATE END HIGH BYTE 1000 READ STATUS/WRITE MODE WORD 1 1001 READ STATUS/WRITE MODE WORD 2 1010 READ SCIENCE DATA TRANSFER COUNTER 1011 READ STATUS/WRITE MODE WORD 3 1100 WRITE: SOFTWARE RESET 1101 RESERVED 1110 RESERVED 1111 RESERVED

10. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 1 BIT O: SPARE BIT[2:1] : RATE SELECT 00  1 HZ 01  6 HZ 10  8 HZ (POWER-ON DEFAULT) 11  10 HZ BIT 3: REAL/SYNTHETIC DATA 0  REAL DATA(POWER-ON DEFAULT) 1  TEST DATA BIT[6:4] : DATA BUILT-IN-TEST PATTERN 000  REAL DATA (POWER-ON DEFAULT) OTHERS  TEST DATA PATTERNS DETAILS ON FOLLOWING PAGE BIT 7: BYTE/NIBBLE MODE 0  BYTE TRANSFERS (POWER-ON DEFAULT) 1  NIBBLE TRANSFERS, EACH NIBBLE REPEATED TWICE, ON DATA LINES, 7:4, 3:0

11. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 1 (cont'd) Built-in Test Control BIT 3: REAL/SYNTHETIC DATA 0  REAL DATA(POWER-ON DEFAULT) 1  TEST DATA BIT[6:4] : DATA BUILT-IN-TEST PATTERN 000  REAL DATA (POWER-ON DEFAULT) 001  00/FF for even/odd-numbered bytes 010  CHECKERBOARD (AA) 011  ~CHECKERBOARD (55) 100  COUNTER 101  ~COUNTER 110  FF/00 for even/odd-numbered bytes 110  REAL DATA

12. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 2 BIT O: CPU CYCLE SLIP (A K A. BABBLE BIT) 0  NO CYCLE SLIP (“GOOD”) 1  CYCLE SLIP (“BAD”) BIT 1: 1PPS ENABLE 0  1PPS INHIBITED (POWER-ON DEFAULT) 1  1PPS ENABLED BIT 2: SPARE BIT 3: SPARE BIT 4: SPARE BIT 5: CLOCK SELECT BIT 6: CLOCK SELECT BIT 7: CLOCK SELECT

13. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 2 (cont'd) BIT [7:5] : CLOCK SELECT OPTIONS 000 => INTERNAL (40% DUTY CYCLE) X01 => OSC B X10 => OSC A 111 => INTERNAL (50% DUTY CYCLE)

14. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 3 BIT O: CAL ENABLE 1 BIT 1: CAL ENABLE 0 BIT 2: CAL SELECT 1 BIT 3: CAL SELECT 0 BIT 4: CYCLE RESET TOF ENABLE 1 BIT 5: CYCLE RESET TOF ENABLE 0 BIT 6: SPARE BIT 7: SPARE CAL ENABLE 1 CAL ENABLE 0 0 0 REAL DATA 0 1 REAL DATA 1 0 REAL DATA 1 1 TOF-A CALIBRATION DATA (TX TRAIL, LITTLE PULSES ONLY CAL SELECT 1 CAL SELECT 0 0 0 0 NS CALIBRATION PULSES 0 1 200 NS CALIBRATION PULSES 1 0 400 NS CALIBRATION PULSES 1 1 200 NS CALIBRATION PULSES THE TOF-A'S ARE ALWAYS RESET ON APPLICATION OF: HARDWARE POWER-ON RESET SOFTWARE POWER-ON RESET IF BOTH BITS 4 AND 5 ARE HIGH, THEN THE TOF-A'S WILL ALSO BE RESET EVERY CYCLE RESET, WHICH PULSES AFTER TIMEZERO AND BEFORE LASERFIRE.

15. November 27, 2002 RMU-CPU Interface - Version 1.8 MODE/STATUS WORD 3 (cont'd) BIT [1:0]: CAL ENABLE 00 REAL DATA 01 REAL DATA 10 REAL DATA 11 CAL DATA BIT [3:2]: CAL SELECT 00 01 10 11 BIT [5:4]: CYCLE RESET 00 01 10 11

16. November 27, 2002 RMU-CPU Interface - Version 1.8 Science Data Packet Definition (1)

17. November 27, 2002 RMU-CPU Interface - Version 1.8 Science Data Packet Definition (2)

18. November 27, 2002 RMU-CPU Interface - Version 1.8 Science Data Packet Definition (3)

19. November 27, 2002 RMU-CPU Interface - Version 1.8 Science Data Packet Definition (4) Each timestamp value for all pulses (Start, Big and Little ) will consist of three fields –Fine Time: Bits [9..0] –Coarse Time: Start Pulse: Bits [30..10] Big Pulse: Bits [30..10] Little Pulse: Bits [27..10] –Miscellaneous (IDs, etc.): as specified for each type of Pulse Each bin is “worth”: –For Fine Time 200/512 ns –for Coarse Time 200 ns To “reconstruct” actual time from Coarse and Fine Time fields, convert each value to “ns” according to the above, then subtract Fine Time from Coarse Time (see next page)

20. November 27, 2002 RMU-CPU Interface - Version 1.8 Science Data Packet Definition (5) Example: Start Pulse Data = “10000000000000100000000000001010” –black: Pulse ID –red/bold: Coarse Time Field –green/italic: Fine Time Field Actual timestamp is calculated as 128*200 - 10*(200/512) = 25596.09375(ns)

21. November 27, 2002 RMU-CPU Interface - Version 1.8 Miscellaneous Range gate start and stop values will also have power-on defaults. They are TBD. A software reset will force values to their power-on default state. RUPT pulse width is 6.4 µs. Following each write (except for software reset) the software will immediately read back the octet written and verify that it is correct.

22. November 27, 2002 RMU-CPU Interface - Version 1.8 1PPS Characteristics t W = TBD Phase relationship to the  5MHz at the RMU - TBD Single string If not present, the RMU will free run Bit 1 in MODE word 2 can disable the 1PPS signal.

23. November 27, 2002 RMU-CPU Interface - Version 1.8 PIN ASSIGNMENTS RMU  CPU RMU_DATA7 ? RMU_DATA6 ? RMU_DATA5 ? RMU_DATA4 ? RMU_DATA3 ? RMU_DATA2 ? RMU_DATA1 ? RMU_DATA0 ? RMU_PARITY ? RMU_SPARE0 ? RMU_SPARE1 ? RUPT ? RMU  CPU CPU_DATA7 ? CPU_DATA6 ? CPU_DATA5 ? CPU_DATA4 ? CPU_DATA3 ? CPU_DATA2 ? CPU_DATA1 ? CPU_DATA0 ? CPU_ADDR3 ? CPU_ADDR2 ? CPU_ADDR1 ? CPU_ADDR0 ? CPU_RD ? CPU_WR ? 1PPS ? RMU_SPARE0 ? RMU_SPARE1 ? GROUNDS, ETC.

24. November 27, 2002 RMU-CPU Interface - Version 1.8 CYCLE TIMING CPU_RD and CPU_WR –Both active high strobes –t Wmin = 250 ns (both high and low) CPU_ADDR –t su to trailing edge of strobe = 250 ns –t h from trailing edge of strobe = 250 ns CPU_DATA –t su to trailing edge of CPU_WR = 250 ns –t h from trailing edge of CPU_WR = 250 ns RMU_DATA –t su to trailing edge of CPU_RD = 100 ns –t h from trailing edge of CPU_RD = 100 ns