UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
890 of 1269
NXP Semiconductors
UM10503
Chapter 30: LPC43xx Motor Control PWM (MOTOCONPWM)
A capture event on a channel causes the following:
•
The current value of the TC is stored in the Capture register (CAP).
•
If the channel’s capture event interrupt is enabled (see
), the capture event
interrupt flag is set.
•
If the channel’s RT bit is set in the CAPCON register, enabling reset on a capture
event, the input event has the same effect as matching the channel’s TC to its LIM
register. This includes resetting the TC and switching the MCO pin(s) in edge-aligned
mode as described in
and
.
30.8.5 External event counting (Counter mode)
If a channel’s MODE bit is 1 in CNTCON, its TC is incremented by rising and/or falling
edge(s) (synchronously detected) on the MCI0-2 input(s), rather than by PCLK. The PWM
functions and capture functions are unaffected.
30.8.6 Three-phase DC mode
The three-phase DC mode is selected by setting the DCMODE bit in the CON register.
In this mode, the internal MCOA0 signal can be routed to any or all of the MCO outputs.
Each MCO output is masked by a bit in the current commutation pattern register CP. If a
bit in the CP register is 0, its output pin has the logic level for the passive state of output
MCOA0. The polarity of the off state is determined by the POLA0 bit.
All MCO outputs that have 1 bits in the CP register are controlled by the internal MCOA0
signal.
The three MCOB output pins are inverted when the INVBDC bit is 1 in the CON register.
This feature accommodates bridge-drivers that have active-low inputs for the low-side
switches.
The CP register is implemented as a shadow register pair, so that changes to the active
communication pattern occur at the beginning of a new PWM cycle. See
and
for more about writing and reading such registers.
shows sample waveforms of the MCO outputs in three-phase DC mode. Bits 1
and 3 in the CP register (corresponding to outputs MCOB1 and MCOB0) are set to 0 so
that these outputs are masked and in the off state. Their logic level is determined by the
POLA0 bit (here, POLA0 = 0 so the passive state is logic LOW). The INVBDC bit is set to
0 (logic level not inverted) so that the B output have the same polarity as the A outputs.
Note that this mode differs from other modes in that the MCOB outputs are
not
the
opposite of the MCOA outputs.
In the situation shown in
, bits 0, 2, 4, and 5 in the CP register are set to 1. That
means that MCOA1 and both MCO outputs for channel 2 follow the MCOA0 signal.