Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Synchronizing Turbo PMAC to External Events
355
Synchronizing Clock Signals over MACRO Ring
If the multiple Turbo PMACs to be synchronized are Turbo PMAC2s on a common MACRO ring, the
synchronization will be achieved automatically over the ring. In this case, each Turbo PMAC2 generates
its own clock signals using MACRO IC 0 (so I6800, I6801, and I6802 control the frequency), but these
signals are forced into full synchronization through use of the “sync packet” passed over the MACRO
ring. I6800, I6801, and I6802 should be set to obtain the same nominal frequencies on all controllers, so
any synchronizing corrections are small, and do not affect performance.
synchronization will be achieved automatically over the ring. In this case, each Turbo PMAC2 generates
its own clock signals using MACRO IC 0 (so I6800, I6801, and I6802 control the frequency), but these
signals are forced into full synchronization through use of the “sync packet” passed over the MACRO
ring. I6800, I6801, and I6802 should be set to obtain the same nominal frequencies on all controllers, so
any synchronizing corrections are small, and do not affect performance.
One Turbo PMAC2 on the MACRO ring must be set up as the synchronizing ring master. It will force
the clock signals on other devices on the ring into full synchronization. I6840 for this controller must be
set to $xx30. Other Turbo PMAC2s on the ring are masters but not the ring master. I6840 for these
controllers must be set to $xx90.
the clock signals on other devices on the ring into full synchronization. I6840 for this controller must be
set to $xx30. Other Turbo PMAC2s on the ring are masters but not the ring master. I6840 for these
controllers must be set to $xx90.
Generally, the Node 15 data packet sent from the ring master is the sync packet. Bit 15 of I6841 on this
controller must be set to 1 to enable the sending of this packet. On the other controllers, bits 16 to 19 (the
second hex digit) of I6841 must all be set to 1 (making the second hex digit $F, or 15) to specify this as
the sync packet, and bit 15 of I6840 must be set to 1 (e.g. I6840 = $8090) to enable the controller to
accept this packet from another master.
controller must be set to 1 to enable the sending of this packet. On the other controllers, bits 16 to 19 (the
second hex digit) of I6841 must all be set to 1 (making the second hex digit $F, or 15) to specify this as
the sync packet, and bit 15 of I6840 must be set to 1 (e.g. I6840 = $8090) to enable the controller to
accept this packet from another master.
Sharing Clock Signals on the Serial Port
If the Turbo PMACs to be synchronized are not linked on a common MACRO ring, the solution to this
problem is to have all the cards physically share common phase and servo clock signals. With Turbo
PMAC, this is done over spare lines on the main serial port (RS-422 connector only). A straight-across
flat cable between the serial ports of multiple Turbo PMACs will connect these clock signals directly
from one card to another. It is acceptable, but not necessary, to connect the serial communications signals
between cards on the same cable. It is acceptable, but not necessary, to connect the clock signals and/or
the serial communications signals to a host computer on the same cable.
problem is to have all the cards physically share common phase and servo clock signals. With Turbo
PMAC, this is done over spare lines on the main serial port (RS-422 connector only). A straight-across
flat cable between the serial ports of multiple Turbo PMACs will connect these clock signals directly
from one card to another. It is acceptable, but not necessary, to connect the serial communications signals
between cards on the same cable. It is acceptable, but not necessary, to connect the clock signals and/or
the serial communications signals to a host computer on the same cable.
A jumper or set of jumpers in each Turbo PMAC system controls whether that Turbo PMAC will
generate its own phase and servo clock signals from its own crystal frequency and output them on its
main serial port, or expect to receive phase and servo clock signals from an external source through its
serial port. Note that a Turbo PMAC set up to receive external clock signals will fail immediately with a
watchdog timer trip if it does not receive these signals.
generate its own phase and servo clock signals from its own crystal frequency and output them on its
main serial port, or expect to receive phase and servo clock signals from an external source through its
serial port. Note that a Turbo PMAC set up to receive external clock signals will fail immediately with a
watchdog timer trip if it does not receive these signals.
In a board-level Turbo PMAC, base-board jumpers E40 – E43 must all be ON for it to generate its own
clock signals. If any of these is removed, it will expect its clock signals through the serial port. In a
board-level Turbo PMAC2, base-board jumper E1 must be OFF for it to generate its own clock signals; if
E1 is ON, it will expect its clock signals through the serial port.
clock signals. If any of these is removed, it will expect its clock signals through the serial port. In a
board-level Turbo PMAC2, base-board jumper E1 must be OFF for it to generate its own clock signals; if
E1 is ON, it will expect its clock signals through the serial port.
On a UMAC Turbo CPU board, jumper E1A must connect pins 1 and 2, and E1B must connect pins 2
and 3 for the UMAC to generate its own clock signals. If E1A connects pins 2 and 3, and E1B connects
pins 1 and 2, it will expect to receive its clock signals through the serial port and pass them on to the
UBUS backplane.
and 3 for the UMAC to generate its own clock signals. If E1A connects pins 2 and 3, and E1B connects
pins 1 and 2, it will expect to receive its clock signals through the serial port and pass them on to the
UBUS backplane.
Only one Turbo PMAC of those sharing clock signals can be set up to generate its own phase and servo
clocks. All others must be set up to input these clock signals. Of course, only the clock-frequency
control jumpers or I-variables on the Turbo PMAC that is generating the clock signals really matter.
However, it is a good idea to set up the other Turbo PMACs for the same nominal frequencies. If PWM
signals are generated on any Turbo PMAC in the system, the PWM frequency is restricted to
N*PhaseFreq/2, where N is a positive integer.
clocks. All others must be set up to input these clock signals. Of course, only the clock-frequency
control jumpers or I-variables on the Turbo PMAC that is generating the clock signals really matter.
However, it is a good idea to set up the other Turbo PMACs for the same nominal frequencies. If PWM
signals are generated on any Turbo PMAC in the system, the PWM frequency is restricted to
N*PhaseFreq/2, where N is a positive integer.
The I10 servo-period parameter must be set to the same value on all of these Turbo PMACs to maintain
precise synchronization.
precise synchronization.