User's Manual
PMAC2 User Manual
20 Setting Up PMAC2 for Direct PWM Control
Commutation Enable: Ix01
Ix01 is set to 1 to instruct PMAC2 to perform the phase commutation for this motor. If PMAC2 is
performing the digital current loop closure, it must also perform the phase commutation for the motor.
Note:
Direct PWM control of brush motors with digital current loop utilizes PMAC2’s
commutation algorithms even though the motor does not require electronic
commutation; Ix01 must be set to 1 for this case
Command Output Address: Ix02
Ix02 instructs PMAC2 where to place its output commands for Motor x by specifying the address. The
default values of Ix02 use the PWM registers A, B, and potentially C for Machine Interface Channel n,
where n=x. Ix02 seldom needs to be changed from the default value for PWM applications. The actual
address specified is that of the PWM A register; PMAC2 then automatically writes to the B and C
registers as well. Usually the values used are:
Chan # 1 2 3 4 5 6 7 8
Ix02 $C002 $C00A $C012 $C01A $C022 $C02A $C032 $C03A
When performing direct PWM control over the MACRO ring, Ix02 points to the first of a set of three
MACRO output registers for the node used. Typically, the values used are dependent on whether
MACRO Type 0 or Type 1 protocol is employed for the node:
Node # 0 1 4 5 8 9 12 13
Type 0
$C0A1 $C0A5 $C0A9 $C0AD $C0B1 $C0B5 $C0B9 $C0BD
Type 1
$C0A0 $C0A4 $C0A8 $C0AC $C0B0 $C0B4 $C0B8 $C0BC
Current Feedback Address: Ix82
Ix82 instructs PMAC2 where to look for its current feedback values for Motor x. It also acts as the
variable that tells PMAC2 whether or not to perform current-loop closure itself. If Ix82=0 (the default),
PMAC2 will not execute the current loop for Motor x; any current loop must be executed in the amplifier.
If Ix82>0, PMAC2 will look at the Y-register whose address is specified by Ix82, and for a multi-phase
motor, the next lower addressed register, to get the current feedback information for its current loop.
Almost always, the registers specified are the serial ADC shift registers in PMAC2’s gate array IC. The
actual address specified is that of the ADC B register; PMAC2 then automatically reads from the A
register as well. Usually, the values used are:
Chan # 1 2 3 4 5 6 7 8
Hex
$C006 $C00E $C016 $C01E $C026 $C02E $C036 $C03E
When performing direct PWM control over the MACRO ring, Ix82 points to the second of a set of two
MACRO input registers for the node used. Usually, the values used are the same whether MACRO Type
0 or Type 1 protocol is employed for the node:
Node # 0 1 4 5 8 9 12 13
Ix02
$C0A2 $C0A6 $C0AA $C0AE $C0B2 $C0B6 $C0BA $C0BE
Current Feedback Mask Word: Ix84
Ix84 specifies a mask word to tell PMAC2 what bits of the registers specified by Ix82 are to be used in
the current-loop algorithm. This permits the use of ADCs of various resolutions; it also permits use of the
rest of the 18-bit ADC shift register for other information, such as fault codes. Ix84 is a 24-bit value that
is combined with the feedback word in a bit-by-bit AND operation. The default value of $FFF000
specifies that the top 12 bits of the feedback words are to be used. The Delta Tau interface boards
designed to date use 12-bit ADCs, so $FFF000 is the appropriate value for these boards.