User's Manual

16-Axis MACRO CPU User Manual
16-Axis MACRO CPU Software Setup 39
ADC Strobe Word: MI941 controls the ADC strobe signal used to interface to serial A/D converters
brought in on Channels 1-4. The default value of $FFFFFE is suitable for most A/D converter types used
with the 16-Axis MACRO CPU, either for digital current loop feedback, or for general-purpose use from
an Acc-28B.
On Board Auxiliary Channels (Handwheel/Pulse and Direction)
There are several variables that affect all of the machine interface channels 9 and 10 which are present on
the 2-Axis piggyback board.
PWM Frequency: MI992 controls the PWM frequency of Channels 9 and 10, as well as the MaxPhase
clock frequency from which the phase clock frequency for the entire MACRO Station is derived (see
above). The equation is:
PWM Frequency (kHz) = 117,964.8 / [4*MI992 + 6]
The MaxPhase frequency is exactly twice the PWM 9-10 frequency.
Hardware Clock Frequencies: MI993 controls the frequencies of the four hardware clock signals for
Channels 9 and 10: the encoder sample SCLK, the pulse-and-direction PFMCLK, the analog output
DAccLK, and the analog input ADCCLK. MI993 is a 12-bit value consisting of four independent 3-bit
parts, each controlling one of the clock frequencies. The equation is:
MI993 = SCLK Divider + 8*PFMCLK Divider + 64*DAccLK Divider
+ 512*ADCCLK Divider
The value of each clock divider can take a value of 0 to 7 and the frequency of each clock signal is:
Clock Frequency = 39.3216 MHz / [2^Clock Divider]
The default value for MI993 of 2258 is suitable for most applications. Refer to the detailed description in
the MACRO Station Hardware Reference Manual to change any of these frequencies.
PWM Deadtime/PFM Pulse Width: MI994 controls both the deadtime for PWM outputs on Channels 9
and 10 and the pulse width for the PFM pulse-and-direction outputs on Channels 9 and 10. The equations are:
PWM Deadtime ( µ sec) = 0.135 * MI994
PFM Pulse Width (
µ sec) = MI994 / PFMCLK Freq. (MHz)
DAC Strobe Word: MI999 controls the DAC strobe signal used to create analog outputs for Channels 9
and 10. It is a 24-bit word that is shifted out one bit per DAccLK cycle, MSB first, starting on the rising
edge of the phase clock.
MI999 should be set to the default value of $7FFF00 for use with the on-board 16-bit DACs that come
with the Option A PMAC-style interface on the Acc-1E 2-Axis piggyback board, or on an Acc-8A
breakout board that attaches to the PMAC2-style connector on the Acc-1E. MI999 should be set to
$7FFFC0 for use with the 18-bit DACs on the Acc-8E PMAC2-style breakout board that attaches to the
PMAC2-style connector on the Acc-1E.
ADC Strobe Word: MI942 controls the ADC strobe signal used to interface to serial A/D converters
brought in on Channels 9 and 10. The default value of $FFFFFE is suitable for most A/D converter types
used with the 16-Axis MACRO CPU, either for digital current loop feedback, or for general-purpose use
from an Acc-28B.