COBHAM GR740 User Manual

GR740-UM-DS, Nov 2017, Version 1.7 246 www.cobham.com/gaisler
GR740
Table 292. GR1553B transfer descriptor result word (offset 0x0C)
31302423 1615 874320
0 Reserved RT2ST RTST RETCNT RES TFRST
31 Always written as 0
30:24 Reserved - Mask away on read for forward compatibility
23:16 RT 2 Status Bits (RT2ST) - Status bits from receiving RT in RT-to-RT transfer, otherwise 0
Same bit pattern as for RTST below
15:8 RT Status Bits (RTST) - Status bits from RT (transmitting RT in RT-to-RT transfer)
15 - Message error, 14 - Instrumentation bit or reserved bit set, 13 - Service request, 
12 - Broadcast command received, 11 - Busy bit, 10 - Subsystem flag, 9 - Dynamic bus control acceptance, 8 - Termi-
nal flag
7:4 Retry count (RETCNT) - Number of retries performed
3 Reserved - Mask away on read for forward compatibility
2:0 Transfer status (TFRST) - Outcome of last try
000 - Success (or dummy bit was set)
001 - RT did not respond (transmitting RT in RT-to-RT transfer)
010 - Receiving RT of RT-to-RT transfer did not respond
011 - A responding RT:s status word had message error, busy, instrumentation or reserved bit set (*)
100 - Protocol error (improperly timed data words, decoder error, wrong number of data words)
101 - The transfer descriptor was invalid
110 - Data buffer DMA timeout or error response
111 - Transfer aborted due to loop back check failure
* Error code 011 is issued only when the number of data words match the success case, otherwise code 100 is used. Error code 011 can be
issued for a correctly executed “transmit last command” or “transmit last status word” mode code since these commands do not reset the status
word.
Table 293.GR1553B BC Transfer configuration bits for different transfer types
Transfer type
RTAD1
(15:11)
RTSA1
(9:5)
RTAD2
(25:21)
RTSA2
(20:16)
WCMC
(4:0)
TR
(10)
Data buffer
direction
Data, BC-to-RT RT address
(0-30)
RT subaddr
(1-30)
Don’t care 0 Word count
(0 for 32)
0Read
(2-64 bytes)
Data, RT-to-BC RT address
(0-30)
RT subaddr
(1-30)
Don’t care 0 Word count
(0 for 32)
1Write
(2-64 bytes)
Data, RT-to-RT Recv-RT
addr (0-30)
Recv-RT
subad. (1-30)
Xmit-RT
addr (0-30)
Xmit-RT
subad. (1-30)
Word count
(0 for 32)
0Write 
(2-64 bytes)
Mode, no data RT address
(0-30)
0 or 31 (*) Don’t care Don’t care Mode code
(0-8)
1 Unused
Mode, RT-to-BC RT address
(0-30)
0 or 31 (*) Don’t care Don’t care Mode code
(16/18/19)
1Write 
(2 bytes)
Mode, BC-to-RT RT address
(0-30)
0 or 31 (*) Don’t care Don’t care Mode code
(17/20/21)
0Read 
(2 bytes)
Broadcast
Data, BC-to-RTs
31 RTs subaddr
(1-30)
Don’t care 0 Word count
(0 for 32)
0Read 
(2-64 bytes)
Broadcast
Data, RT-to-RTs
31 Recv-RTs
subad. (1-30)
Xmit-RT
addr (0-30)
Xmit-RT
subad. (1-30)
Word count
(0 for 32)
0Write 
(2-64 bytes)
Broadcast 
Mode, no data
31 0 or 31 (*) Don’t care Don’t care Mode code
(1, 3-8)
1 Unused
Broadcast
Mode, BC-to-RT
31 0 or 31 (*) Don’t care Don’t care Mode code
(17/20/21)
0Read 
(2 bytes)
(*) The standard allows using either of subaddress 0 or 31 for mode commands.

COBHAM GR740 Specifications

General

Brand	COBHAM
Model	GR740
Category	Computer Hardware
Language	English