PIC18F2331_07 Datasheet, PDF (206/400 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High Performance PWM and A/D

PIC18F2331/2431/4331/4431
17.10.3 OUTPUT OVERRIDE EXAMPLES
Figure 17-21 shows an example of a waveform that
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
through a 3-phase inverter as shown in Figure 17-16.
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 out-
puts are driven to specific logic states. The OVDCOND
and OVDCONS register values used to generate the
signals in Figure 17-21 are given in Table 17-4.
The PWM Duty Cycle registers may be used in con-
junction 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 sequence.
Figure 17-22 shows the waveforms, while Table 17-4
and Table 17-5 show the OVDCOND and OVDCONS
register values used to generate the signals.
REGISTER 17-6: OVDCOND: OUTPUT OVERRIDE CONTROL REGISTER
R/W-1
POVD7⁽¹⁾
bit 7
R/W-1
POVD6⁽¹⁾
R/W-1
POVD5
R/W-1
POVD4
R/W-1
POVD3
R/W-1
POVD2
R/W-1
POVD1
R/W-1
POVD0
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-0
POVD7: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 POUT bit
Note 1: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
REGISTER 17-7: OVDCONS: OUTPUT STATE REGISTER
R/W-0
POUT7⁽¹⁾
bit 7
R/W-0
POUT6⁽¹⁾
R/W-0
POUT5
R/W-0
POUT4
R/W-0
POUT3
R/W-0
POUT2
R/W-0
POUT1
R/W-0
POUT0
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-0
POUT7:POUT0: PWM Manual Output bits
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: Unimplemented in PIC18F2331/2431 devices; maintain these bits clear.
DS39616C-page 204
Preliminary
© 2007 Microchip Technology Inc.