Delta Tau GEO BRICK LV Manuel D’Utilisation
Turbo PMAC User Manual
18
Turbo PMAC System Configuration and Auto Configuration
System clock frequencies such as the phase and servo clocks, plus the clock frequencies driving hardware
circuits, are generated directly from the clock-crystal frequency through a Servo IC or a MACRO IC and
are not dependent on the CPU operating frequency. These clock frequencies are covered in the following
sections.
circuits, are generated directly from the clock-crystal frequency through a Servo IC or a MACRO IC and
are not dependent on the CPU operating frequency. These clock frequencies are covered in the following
sections.
Turbo PMAC2 System Clock Source
In a Turbo PMAC2 system, the system phase and servo clocks, which interrupt the processor and latch
key input and output data for the servos, come from one (and only one) of the Servo ICs or MACRO ICs
in the system, or possibly from an external source. There must be a unique source of the phase and servo
clocks for an entire Turbo PMAC2 system. This section explains how to specify that clock source. A
later portion of this section, Setting System Clock Frequencies, explains how to set the frequencies once
the source has been determined.
key input and output data for the servos, come from one (and only one) of the Servo ICs or MACRO ICs
in the system, or possibly from an external source. There must be a unique source of the phase and servo
clocks for an entire Turbo PMAC2 system. This section explains how to specify that clock source. A
later portion of this section, Setting System Clock Frequencies, explains how to set the frequencies once
the source has been determined.
Default Clock Source
The factory-default source for these clock signals is appropriate in almost all applications. Only in
specialized cases will another source be used. The Turbo Setup program will walk you through the setup
of the frequencies for the source selected. Setting the frequencies is discussed in the next section.
specialized cases will another source be used. The Turbo Setup program will walk you through the setup
of the frequencies for the source selected. Setting the frequencies is discussed in the next section.
Note:
A Turbo PMAC board uses fixed, discrete logic to generate its phase and servo
clocks. If accessory boards with Servo ICs or MACRO ICs that can generate their
own clock signals are added to a Turbo PMAC, they must be set up to use the
Turbo PMAC’s phase and servo clock signals. Turbo PMAC systems also do
support external clock sources in the same way that Turbo PMAC2 systems do.
clocks. If accessory boards with Servo ICs or MACRO ICs that can generate their
own clock signals are added to a Turbo PMAC, they must be set up to use the
Turbo PMAC’s phase and servo clock signals. Turbo PMAC systems also do
support external clock sources in the same way that Turbo PMAC2 systems do.
IC Clock Generation Facilities
Each PMAC2-style Servo IC (DSPGATE1 IC) and DSPGATE2-type MACRO IC has the capability for
generating its own phase and servo clock signals, or for accepting external phase and servo clock signals.
(Exception: MACROGATE-type MACRO ICs can generate their own phase clock, but not servo clock.
Therefore, they cannot be used to generate clocks for the entire system.) At most one of these ICs in a
system may generate its own clock signals – none if the signals come from an external source.
generating its own phase and servo clock signals, or for accepting external phase and servo clock signals.
(Exception: MACROGATE-type MACRO ICs can generate their own phase clock, but not servo clock.
Therefore, they cannot be used to generate clocks for the entire system.) At most one of these ICs in a
system may generate its own clock signals – none if the signals come from an external source.
Variables I7m07 and I7m57 control the clock direction for Servo ICs ‘m’ and ‘m*’, respectively.
Variables I6807, I6857, I6907, and I6957 control the clock direction for MACRO ICs 0, 1, 2, and 3,
respectively. If the variable value is 0, the IC generates its own clock signals and outputs them. If the
variable value is 3, the IC accepts the clock signals from a source external to it. At most one of these ICs
can have this variable at a value of 0; the rest must be set to 3.
Variables I6807, I6857, I6907, and I6957 control the clock direction for MACRO ICs 0, 1, 2, and 3,
respectively. If the variable value is 0, the IC generates its own clock signals and outputs them. If the
variable value is 3, the IC accepts the clock signals from a source external to it. At most one of these ICs
can have this variable at a value of 0; the rest must be set to 3.
Note:
If more than one of these ICs is set up to use its own clock signals and to output
them, the processor will be interrupted by multiple sources and will not operate
normally – it is possible that the watchdog timer will trip. (Because the outputs are
open-collector types, there will be no hardware damage from signal contention, but
system software operation will be compromised.)
them, the processor will be interrupted by multiple sources and will not operate
normally – it is possible that the watchdog timer will trip. (Because the outputs are
open-collector types, there will be no hardware damage from signal contention, but
system software operation will be compromised.)