
PIC18F1230/1330
DS39758D-page 140
2009 Microchip Technology Inc.
14.10.3
OUTPUT OVERRIDE EXAMPLES
might be generated using the PWM output override
feature. The figure shows a six-step commutation
sequence for a BLDC motor. The motor is driven
When the appropriate rotor position is detected, the
PWM outputs are switched to the next commutation
state in the sequence. In this example, the PWM
outputs are driven to specific logic states. The
OVDCOND and OVDCONS register values used to
The PWM Duty Cycle registers may be used in
conjunction with the OVDCOND and OVDCONS
registers. The Duty Cycle registers control the average
voltage across the load and the OVDCOND and
OVDCONS
registers
control
the
commutation
OVDCONS register values used to generate the
signals.
REGISTER 14-6:
OVDCOND: OUTPUT OVERRIDE CONTROL REGISTER
U-0
R/W-1
—
POVD5
POVD4
POVD3
POVD2
POVD1
POVD0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented:
Read as ‘0’
bit 5-0
POVD5:POVD0:
PWM Output Override bits
1
= Output on PWM I/O pin is controlled by the value in the Duty Cycle register and the PWM time base
0
= Output on PWM I/O pin is controlled by the value in the corresponding POUTx bit
REGISTER 14-7:
OVDCONS: OUTPUT STATE REGISTER
U-0
R/W-0
—
POUT5
POUT4
POUT3
POUT2
POUT1
POUT0
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-6
Unimplemented:
Read as ‘0’
bit 5-0
POUT5:POUT0:
PWM Manual Output bits(1)
1
= Output on PWM I/O pin is active when the corresponding PWM output override bit is cleared
0
= Output on PWM I/O pin is inactive when the corresponding PWM output override bit is cleared
Note 1:
With PWMs configured in complementary mode, even PWM (PWM0, 2, 4) outputs will be
complementary of the odd PWM (PWM1, 3, 5) outputs, irrespective of the POUT bit
setting.