Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 210
MACRO IC Ring Setup I-variables
I6840/I6890/I6940/I6990 MACRO IC Ring Configuration/Status
Range: $0000 - $FFFF (0 - 65,535)
Units: none
Default: 0
I6840, I6890, I6940, and I6990 contain configuration and status bits for MACRO ring operation of
MACRO ICs 0, 1, 2, and 3, respectively, on the Turbo PMAC2.
There are 11 configuration bits and 5 status bits, as follows:
Bit #
Value
Type
Function
0
1($1)
Status
Data Overrun Error (cleared when read)
1
2($2)
Status
Byte Violation Error (cleared when read)
2
4($4)
Status
Packet Parity Error (cleared when read)
3
8($8)
Status
Packet Underrun Error (cleared when read)
4
16($10)
Config
Master Station Enable
5
32($20)
Config
Synchronizing Master Station Enable
6
64($40)
Status
Sync Node Packet Received (cleared when read)
7
128($80)
Config
Sync Node Phase Lock Enable
8
256($100)
Config
Node 8 Master Address Check Disable
9
512($200)
Config
Node 9 Master Address Check Disable
10
1024($400)
Config
Node 10 Master Address Check Disable
11
2048($800)
Config
Node 11 Master Address Check Disable
12
4096($1000)
Config
Node 12 Master Address Check Disable
13
8192($2000)
Config
Node 13 Master Address Check Disable
14
16384($4000)
Config
Node 14 Master Address Check Disable
15
32768($8000)
Config
Node 15 Master Address Check Disable
In most applications, the only important configuration bits are bits 4, 5, and 7. In every MACRO ring,
there must be one and only one synchronizing master station (each MACRO IC counts as a separate
station; only one MACRO IC on any card in the ring can be a synchronizing master station). For this
MACRO IC, bits 4 and 5 should be set (1), but bit 7 should be clear (0). On a Turbo PMAC2 Ultralite,
this should be MACRO IC 0, for which I6840 should be set to $30, or $xx30 if any of the high bits are to
be set.
If there are more than one MACRO ICs acting as masters on the ring, the others should not be
synchronizing masters, but they should be set up as masters and enable sync node phase lock to stay
synchronized with the synchronizing master. For these MACRO ICs, bit 4 should be set (1), bit 5 should
be clear (0), and bit 7 should be set (1), so I6890/I6940/I6990 should be set to $90, or $xx90 if any of the
high bits are to be set.
Bits 8-15 can be set individually to disable the master address check for their corresponding node
numbers. This capability is for multi-master broadcast and synchronization. If the master address check
is disabled, only the slave node number part of the packet address must match for a packet to be latched
in. In this way, the synchronizing master can send the same data packet to multiple other master and
slave stations. This common packet can be used to keep multiple stations synchronized using the sync
lock function enabled with bit 7 of I6890/I6940/I6990; the packet number is specified in
I6891/I6941/I6991 (packet 15 is suggested for this purpose).