MA828 Datasheet, PDF (9/16 Pages) List of Unclassifed Manufacturers – THREE-PHASE PULSE WIDTH MODULATION WAVEFORM GENERATOR

Control Register Programming Example
The control register would normally be updated many times
while the motor is running, but just one example is given here. It
is assumed that the initialisation register has already heen
programmed with the parameters given in the previous example.
A power waveform of 100Hz is required with a PWM waveform
amplitude of 80% of that stored in the ROM. The phase sequence
should be set to give forward motor rotation.The outputs should
be enabled and no overmodulation is required.
1. Setting the power frequency
The power frequency, f_POWER, can be selected to 12-bit ac-
curacy (i.e 4096 equal steps) from 0Hz to f_RANGE as defined in
the initialisation register. In this case, with f_RANGE = 250Hz, the
power frequency can be adjusted in increments of 0·06Hz.
f_POWER
= ^fRANGE3
4096
pfs
⇒ pfs = ^fPOWER34096 = ^10034096 = 1638·4
f_RANGE
250
We can only have pfs as an integer, so if we assign pfs = 1638
this gives f_POWER = 99.97 Hz.The 12-bit binary equivalent of this
value gives a PFS word of 011001100110 in temporary registers
R0 and R1.
2. Setting overmodulation, forward/reverse, output inhibit
Overmodulation is not required therefore OM = 0.
Forward motor control is required (i.e., the phase sequence
of the PWM outputs should be red-yellow-blue) therefore for-
ward/reverse bit F/R = 0.
Output inhibit should be inactive (i e., the outputs should be
active), therefore INH= 1.
These bits are all set in temporary register R1.
3. Setting the power waveform amplitude
A
A_POWER = ₂₂₅ 3 100%
⇒ A = ^APOWER3255 = ⁸⁰³²⁵⁵ = 204
100
100
The 8-bit binary equivalent of this value gives an AMP word
of 11001100 in temporary register R2. The data which must be
programmed into the three temporary registers R0, R1 and R2
(for transfer into the control register) in order to achieve the
parameters in the example given, is shown in Fig. 16.
Temporary Register R0
01100011
PFS₇ PFS₆ PFS₅ PFS₄ PFS₃ PFS₂ PFS₁ PFS₀
Temporary Register R1
001X0110
F/R OM INH X PFS₁₁ PFS₁₀ PFS₉ PFS₈
Temporary Register R2
11001100
AMP₇ AMP₆ AMP₅ AMP₄ AMP₃ AMP₂ AMP₁ AMP₀
Fig. 16
MA828
POWER ON



WRITE 
 INITIALISATION
DATA _





 ^{WRITE TO CONTROL}
REGISTER INHIBITING
 _{PWM OUTPUTS}
 _{BEFORE COMPLETING}
 _{RESET CYCLE}


ENABLE
PWM OUTPUTS
RST ↓ 0
WRITE R0
WRITE R1
WRITE R2
WRITE R4
WRITE R0
WRITE R1
WRITE R2
WRITE R3
RST ↑ 1



WRITE _
CONTROL _
DATA _



WRITE R0
WRITE R1
WRITE R2
WRITE R3
CHANGE YES
CONTROL
DATA ?
NO
NO
CHANGE
INITIALISATION
DATA ?
YES
Fig. 17 Typical MA828 programming routine
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