Apollo-11/Luminary099/SPS_BACK-UP_RCS_CONTROL.agc

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# Copyright: Public domain.
# Filename: SPS_BACK-UP_RCS_CONTROL.agc
# Purpose: Part of the source code for Luminary 1A build 099.
# It is part of the source code for the Lunar Module's (LM)
# Apollo Guidance Computer (AGC), for Apollo 11.
# Assembler: yaYUL
# Contact: Ron Burkey <info@sandroid.org>.
# Website: www.ibiblio.org/apollo.
# Pages: 1507-1510
# Mod history: 2009-05-27 RSB Adapted from the corresponding
# Luminary131 file, using page
# images from Luminary 1A.
#
# This source code has been transcribed or otherwise adapted from
# digitized images of a hardcopy from the MIT Museum. The digitization
# was performed by Paul Fjeld, and arranged for by Deborah Douglas of
# the Museum. Many thanks to both. The images (with suitable reduction
# in storage size and consequent reduction in image quality as well) are
# available online at www.ibiblio.org/apollo. If for some reason you
# find that the images are illegible, contact me at info@sandroid.org
# about getting access to the (much) higher-quality images which Paul
# actually created.
#
# Notations on the hardcopy document read, in part:
#
# Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
# 16:27 JULY 14, 1969
# Page 1507
# PROGRAM NAME: SPSRCS
# AUTHOR: EDGAR M. OSHIKA (AC ELECTRONICS)
# MODIFIED: TO RETURN TO ALL AXES VIA Q BY P. S. WEISSMAN, OCT 7, 1968
# MODIFIED TO IMPROVE BENDING STABILITY BY G. KALAN, FEB. 14, 1969
#
# FUNCTIONAL DESCRIPTION:
# THE PROGRAM CONTROLS THE FIRING OF ALL RCS JETS IN THE DOCKED CONFIGURATION ACCORDING TO THE FOLLOWING PHASE
# PLANE LOGIC.
#
# 1. JET SENSE TEST (SPSRCS)
# IF JETS ARE FIRING NEGATIVELY, SET OLDSENSE NEGATIVE AND CONTINUE
# IF JETS ARE FIRING POSITIVELY, SET OLDSENSE POSITIVE AND CONTINUE
# IF JETS ARE NOT FIRING, SET OLDSENSE TO ZERO AND GO TO OUTER RATE LIMIT TEST
#
# 2. RATE DEAD BAND TEST
# IF JETS ARE FIRING NEGATIVELY AND RATE IS GREATER THAN TARGET RATE, LEAVE
# JETS ON AND GO TO INHIBITION LOGIC. OTHERWISE, CONTINUE.
# IF JETS ARE FIRING POSITIVELY AND RATE IS LESS THAN TARGET RATE, LEAVE
# JETS ON AND GO TO INHIBITION LOGIC. OTHERWISE, CONTINUE.
#
# 3. OUTER RATE LIMIT TEST (SPSSTART)
# IF MAGNITUDE OF EDOT IS GREATER THAN 1.73 DEG/SEC SET JET FIRING TIME
# TO REDUCE RATE AND GO TO INHIBITION LOGIC. OTHERWISE, CONTINUE.
#
# 4. COAST ZONE TEST
# IF STATE (E,EDOT) IS BELOW LINE E + 4 X EDOT > -1.4 DEG AND EDOT IS LESS THAN 1.30 DEG/SEC SET JET TIME
# POSITIVE AND CONTINUE. OTHERWISE, SET JET FIRING TIME TO ZERO AND CONTINUE.
# IF STATE IS ABOVE LINE E + 4 X EDOT > +1.4 DEG AND EDOT IS GREATER THAN -1.30 DEG/SEC, SET JET TIME NEGATIVE
# AND CONTINUE. OTHERWISE, SET JET FIRING TIME TO ZERO AND CONTINUE.
#
# 5. INHIBITION LOGIC
# IF OLDSENSE IS NON-ZERO:
# A) RETURN IF JET TIME AS THE SAME SIGN AS OLDSENSE
# B) SET INHIBITION COUNTER* AND RETURN IF JET TIME IS ZERO
# C) SET INHIBITION COUNTER,* SET JET TIME TO ZERO AND RETURN IF SIGN
# OF JET TIME IS OPPOSITE TO THAT OF OLDSENSE
# IF OLDSENSE IS ZERO:
# A) RETURN IF INHIBITION COUNTER IS NOT POSITIVE
# B) SET JET TIME TO ZERO AND RETURN IF INHIBITION COUNTER IS POSITIVE
# *NOTE: INHIBITION COUNTERS CAN BE SET TO 4 OR 10 FOR THE P AND UV AXES,
# RESPECTIVELY, IN SPSRCS. THEY ARE DECREMENTED BY ONE AT THE BEGINNING OF
# Page 1508
# EACH DAP PASS.
#
# THE MINIMUM PULSE WIDTH OF THIS CONTROLLER IS DETERMINED BY THE REPETITION RATE AT WHICH THIS ROUTINE IS CALLED
# AND IS NOMINALLY 100 MS FOR ALL AXES IN DRIFTING FLIGHT. DURING POWERED FLIGHT THE MINIMUM IS 100 MS FOR THE
# P AXIS AND 200 MS FOR THE CONTROL OF THE U AND V AXES.
#
# CALLING SEQUENCE:
# INHINT
# TC IBNKCALL
# CADR SPSRCE
#
# EXIT:
# TC Q
#
# ALARM/ABORT MODE: NONE
#
# SUBROUTINES CALLED: NONE
#
# INPUT: E, EDOT
# TJP, TJV, TJU TJ MUST NOT BE NEGATIVE ZERO
#
# OUTPUT: TJP, TJV, TJU
BANK 21
SETLOC DAPS4
BANK
COUNT* $$/DAPBU
EBANK= TJU
RATELIM2 OCT 00632 # 1.125 DEG/SEC
POSTHRST CA HALF
NDX AXISCTR
TS TJU
CCS OLDSENSE
TCF POSCHECK # JETS FIRING POSITIVELY
TCF CTRCHECK # JETS OFF. CHECK INHIBITION CTR
NEGCHECK INDEX AXISCTR # JETS FIRING NEGATIVELY
CS TJU
CCS A
TC Q # RETURN
TCF +2
TCF +1 # JETS COMMANDED OFF. SET CTR AND RETURN
SETCTR INDEX AXISCTR # JET FIRING REVERSAL COMMANDED. SET CTR,
CA UTIME # SET JET TIME TO ZER, AND RETURN
# Page 1509
INDEX AXISCTR
TS UJETCTR
ZAPTJ CA ZERO
INDEX AXISCTR
TS TJU
TC Q
POSCHECK INDEX AXISCTR
CA TJU
TCF NEGCHECK +2
CTRCHECK INDEX AXISCTR # CHECK JET INHIBITION COUNTER
CCS UJETCTR
TCF +2
TC Q # CTR IS NOT POSITIVE. RETURN
TCF ZAPTJ # CTR IS POSITIVE. INHIBIT FIRINGS
TC Q # CTR IS NOT POSITIVE. RETURN
OCT 00004
UTIME OCT 00012
OCT 00012
OLDSENSE EQUALS DAPTREG1
NEGFIRE CS ONE # JETS FIRING NEGATIVELY
TS OLDSENSE
CA EDOT
TCF +4
PLUSFIRE CA ONE
TS OLDSENSE
CS EDOT # RATE DEAD BAND TEST
LXCH A
CS DAPBOOLS # IF DRIFTBIT = 1, USE ZERO TARGET RATE
MASK DRIFTBIT # IF DRIFTBIT = 0, USE 0.10 RATE TARGET
CCS A
CA RATEDB1
AD L
EXTEND
BZMF SPSSTART
TCF POSTHRST +3
SPSRCS INDEX AXISCTR # JET SENSE TEST
CCS TJU
TCF PLUSFIRE # JETS FIRING POSITIVELY
TCF +2
TCF NEGFIRE # JETS FIRING NEGATIVELY
TS OLDSENSE # JETS OFF
SPSSTART CA EDOT # OUTER RATE LIMIT TEST
EXTEND
MP RATELIM1
CCS A
TCF NEGTHRST # OUTER RATE LIMIT EXCEEDED
TCF +2
TCF POSTHRST # OUTER RATE LIMIT EXCEEDED
CA EDOT # COAST ZONE TEST
# Page 1510
AD E
EXTEND
MP DKDB # PAD LOADED DEADBAND. FRESHSTART: 1.4 DEG
EXTEND
BZF TJZERO
EXTEND
BZMF +7
CA EDOT
AD RATELIM2
EXTEND
BZMF TJZERO
NEGTHRST CS HALF
TCF POSTHRST +1
+7 CS RATELIM2
AD EDOT
EXTEND
BZMF POSTHRST
TJZERO CA ZERO
TCF POSTHRST +1
RATELIM1 = CALLCODE # = 00032, CORRESPONDING TO 1.73 DEG/SEC
RATEDB1 = TBUILDFX # = 00045, CORRESPONDS TO 0.101 DEG/SEC
# *** END OF LMDAP .015 ***