Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 194
Turbo PMAC2 MACRO IC I-Variables
I-Variables numbered in the I6800s and I6900s control hardware aspects of the MACRO ICs 0 to 3 of a
Turbo PMAC2. These ICs control the operation of the MACRO ring on all PMAC2 boards. MACRO IC
0, a DSPGATE2 IC, also controls operation of the general-purpose I/O and two supplemental servo
channels. On the Ultralite versions of the Turbo PMAC2, this IC also controls the frequency of the clock
signals on the board, because the DSPGATE1 Servo ICs are not present.
A UMAC Turbo system may have up to 16 MACRO ICs present, but only four of these can be supported
by automatic firmware functions at any given time.
Starting in V1.936 firmware, I20 through I23 must contain the base addresses of MACRO ICs 0 through
3, respectively. If these are not set correctly, the automatic firmware functions associated with these ICs,
including the I-variables I6800 – I6999, will not function.
Configuration status variable I4902 tells where MACRO ICs are present; I4903 tells whether these ICs
are MACROGATE ICs or DSPGATE2 ICs. Some functions and there supporting I-variables are
available only on DSPGATE2 ICs.
The numbering scheme for the MACRO IC I-Variables is as follows:
 MACRO IC 0: I6800 – I6849
 MACRO IC 1: I6850 – I6899
 MACRO IC 2 I6900 – I6949
 MACRO IC 3 I6590 – I6999
Only the Ultralite and 3U versions of the Turbo PMAC2 may contain MACRO ICs 1, 2, and 3, and these
ICs are optional. MACRO ICs 1, 2, and 3 are MACROGATE ICs that only have the MACRO ring
functionality.
I6800/I6850/I6900/I6950 MACRO IC MaxPhase/PWM Frequency Control
Range: 0 - 32767
Units: MaxPhase Frequency = 117,964.8 kHz / [2*I6800+3]
PWM Frequency = 117,964.8 kHz / [4*I6800+6]
Default: 6527
MaxPhase Frequency = 117,964.8 / 13,057 = 9.0346 kHz
PWM Frequency = 117,964.8 / 26,114 = 4.5173 kHz
I6800, I6850, I6900, and I6950 control the internal MaxPhase clock frequency, and the PWM frequency
for the two machine interface channels (if present), on MACRO ICs 0, 1, 2, and 3, respectively. The
internally generated Phase and Servo clocks on a MACRO IC are derived from the MaxPhase clock.
If the IC is used to generate the Phase and Servo clocks for the PMAC system (as set by I6807 etc.), this
variable is part of the control for the frequency of these clocks.
On a Turbo PMAC2 Ultralite board, MACRO IC 0 provides the Phase and Servo clock signals for the
entire board, so I6800 is used to derive the Phase clock and Servo clock frequencies for the board, along
with I6801 and I6802. (On Turbo PMAC2 boards that are not Ultralite, typically this function is
controlled by I7000, I7001, and I7002, because Servo IC 0 usually controls the board clock frequencies
on these boards.) In a UMAC Turbo system, the MACRO IC on an Acc-5E board can be used to control
these clocks.
MACROGATE ICs, commonly used as MACRO ICs 1, 2, and 3, generate no PWM signals and no Servo
clock signal. Therefore, they cannot be used as the source of the system Phase and Servo clocks, and the
only purpose of this variable is for control of the internal Phase clock signal.