Reference Manual

PMAC 2 Software Reference
152 PMAC I-Variable Specifiation
I994 ≅ 1 usec / 0.135 usec ≅ 7
With a 2.4576 MHz PFM_CLK frequency, a pulse width of 0.4 usec is desired:
I994 ≅ 2.4576 MHz * 0.4 usec ≅ 1
I995 MACRO Ring Configuration/Status {PMAC2 only}
Range
$0000 .. $FFFF (0 - 65,535)
Units
none
Default
0
Remarks
I995 contains configuration and status bits for MACRO ring operation of the 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. On this card, bits 4
and 5 should be set (1), but bit 7 should be clear (0). On this card, I995 should be set to
$30, or $xx30 if any of the high bits are to be set.
If there are more that one PMAC2 acting as a masters on the ring, these should not be
synchronizing masters, but they should enable “sync node phase lock” to stay
synchronized with the synchronizing master. One these cards, bit 4 should be set, bit 5
should be clear, and bit 7 should be set, so I995 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 I995; the packet number is specified in I996
(packet 15 is suggested for this purpose).