Delta Tau Geo MACRO, User Manual And Reference Manual

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Geo MACRO Drive User and Reference Manual
Geo Macro Drive MI-Variable Reference 157
SCLK Divider N: 5
PFM_CLK Divider N: 4
DAC_CLK Divider N: 3
ADC_CLK Divider N: 4
MI993 = 5 + (8 * 4) + (64 * 3) + (512 * 4) = 5 + 32 + 192 + 2048 = 2277
MI993 has been set to 3429. What clock frequencies does this set?
N1 = INT (3429/512) = 6 ADC_CLK = 611.44 kHz
MI993' = 3429 - (512*6) = 357
N2 = INT (357/64) = 5 DAC_CLK = 1.2288 MHz
MI993'' = 357 - (64*5) = 37
N3 = INT (37/8) = 4 PFM_CLK = 2.4576 MHz
N4 = 37 - (8*4) = 5 SCLK = 1.2288 MHz
MS{node},MI994 PWM Deadtime
Range: 0 - 255
Units: PWM Deadtime = [16 / PWM_CLK (MHz)] * MI994 = 0.135
µ
sec * MI994
PFM Pulse Width = [1 / PFM_CLK (MHz)] * MI994
= PFM_CLK_period (
µ
sec) * MI994
Default: 15
PWM Deadtime = 0.135
µ
sec * 15 = 2.03
µ
sec
PFM Pulse Width = [1 / 9.8304 MHz] * 15 = 1.526
µ
sec (with default MI993)
MI994 controls the deadtime period between top and bottom on-times in the Geo MACRO Station’s
automatic PWM generation for machine interface handwheel channels 19 and 2. In conjunction with
MI993, it also controls the pulse width for PMAC2’s automatic pulse-frequency modulation generation
for these machine interface channels.
The PWM deadtime, which is the delay between the top signal turning off and the bottom signal turning
on and vice versa, is specified in units of 16 PWM_CLK cycles. This means that the deadtime can be
specified in increments of 0.135
µ
sec. The equation for MI994 as a function of PWM deadtime is:
MI994 = Deadtime (
µ
sec) / 0.135
µ
sec
The PFM pulse width is specified in PFM_CLK cycles, as defined by MI993. The equation for MI994 as
a function of PFM pulse width and PFM_CLK frequency is:
MI994 = PFM_CLK Freq (MHz) / PFM pulse width (
µ
sec)
In PFM pulse generation, the minimum off time between pulses is equal to the pulse width. This means
that the maximum PFM output frequency is
PFM Max_Freq (MHz) = PFM_CLK Freq / (2 * MI994)
Examples:
A PWM deadtime of approximately 1 microsecond is desired:
MI994
≅
1
µ
sec / 0.135
µ
sec
≅
7
With a 2.4576 MHz PFM_CLK frequency, a pulse width of 0.4
µ
sec is desired:
MI994
≅
2.4576 MHz * 0.4
µ
sec
≅
1
MS{node},MI995 MACRO Ring Configuration/Status
Range: $0000 - $FFFF (0 - 65,535)
Units: none
Default: $0080