User's Manual

16-Axis MACRO CPU User Manual
38 16-Axis MACRO CPU Software Setup
The default value for MI903 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: MI904 controls both the deadtime for PWM outputs on Channels
1-4 and the pulse width for the PFM pulse-and-direction outputs on Channels 1-4. The equations are:
PWM Deadtime( µ sec) = 0.135 * MI904
PFM Pulse Width (
µ sec) = MI904 / PFMCLK Freq. (MHz)
DAC Strobe Word: MI905 controls the DAC strobe signal used to create analog outputs for Channels 1-
4. 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.
MI905 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-2E 4-Axis piggyback board, or on an Acc-8A
breakout board that attaches to the PMAC2-style connectors on the Acc-2E. MI905 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 connectors on the Acc-2E, or the Acc-24E2A backplane analog Axis-interface/breakout
board.
ADC Strobe Word: MI940 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 or Acc-28E board.
Channels 5-8 (Second 4-Axis Board)
There are several variables that affect all of the machine interface channels 5 to 8.
PWM Frequency: MI906 controls the PWM frequency of Channels 5-8. Its setting is important only if
the PWM outputs are used through the PMAC2-style connectors. The equation for the frequency is:
PWM Frequency (kHz) = 117,964.8 / [4*MI906 + 6]
Generally, MI906 is set to the same value as MI992 which controls the MaxPhase clock frequency. The
PWM frequency set by MI906 must be equal to N/2 times the Phase clock frequency set by MI992 and
MI997 where N is a positive integer.
Hardware Clock Frequencies: MI907 controls the frequencies of the four hardware clock signals for
Channels 5-8: the encoder sample SCLK, the pulse-and-direction PFMCLK, the analog output DAccLK,
and the analog input ADCCLK. MI907 is a 12-bit value consisting of four independent 3-bit parts, each
controlling one of the clock frequencies. The equation is:
MI907 = 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 MI907 of 2258 is suitable for almost all applications. Refer to the detailed
description in the MACRO Station Hardware Reference Manual to change any of these frequencies.
PWM Deadtime/PFM Pulse Width: MI908 controls both the deadtime for PWM outputs on Channels
5-8 and the pulse width for the PFM pulse-and-direction outputs on Channels 5-8. The equations are:
PWM Deadtime ( µ sec) = 0.135 * MI908
PFM Pulse Width (
µ sec) = MI908 / PFMCLK Freq. (MHz)
DAC Strobe Word: MI909 controls the DAC strobe signal used to create analog outputs for Channels 5-
8. 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.
MI909 should be set to $7FFFC0 for use with the 18-bit DACs on the Acc-24E2A backplane analog axis-
interface/breakout board.