UM10503
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User manual
Rev. 1.3 — 6 July 2012
874 of 1269
NXP Semiconductors
UM10503
Chapter 30: LPC43xx Motor Control PWM (MOTOCONPWM)
If the channel’s CENTER bit in CON is 0 selecting edge-aligned mode, the match between
TC and LIM switches the channel’s A output from “active” to “passive” state. If the
channel’s CENTER and DTE bits in CON are both 0, the match simultaneously switches
the channel’s B output from “passive” to “active” state.
If the channel’s CENTER bit is 0 but the DTE bit is 1, the match triggers the channel’s
deadtime counter to begin counting -- when the deadtime counter expires, the channel’s B
output switches from “passive” to “active” state.
In center-aligned mode, matches between a channel’s TC and LIM registers have no
effect on its A and B outputs.
Writing to either a Limit or a Match (
) register loads a “write” register, and if the
channel is stopped it also loads an “operating” register that is compared to the TC. If the
channel is running and its “disable update” bit in CON is 0, the operating registers are
loaded from the write registers: 1) in edge-aligned mode, when the TC matches the
operating Limit register; 2) in center-aligned mode, when the TC counts back down to 0. If
the channel is running and the “disable update” bit is 1, the operating registers are not
loaded from the write registers until software stops the channel.
Reading an LIM address always returns the operating value.
Remark:
In timer mode, the period of a channel’s modulated MCO outputs is determined
by its Limit register, and the pulse width at the start of the period is determined by its
Match register. If it suits your way of thinking, consider the Limit register to be the “Period
register” and the Match register to be the “Pulse Width register”.
30.7.5 MCPWM Match 0-2 registers
These registers also have “write” and “operating” versions as described above for the
Limit registers, and the operating registers are also compared to the channels’ TCs. See
above for details of reading and writing both Limit and Match registers.
The Match and Limit registers control the MCO0-2 outputs. If a Match register is to have
any effect on its channel’s operation, it must contain a smaller value than the
corresponding Limit register.
30.7.5.1 Match register in Edge-Aligned mode
If the channel’s CENTER bit in CON is 0 selecting edge-aligned mode, a match between
TC and MAT switches the channel’s B output from “active” to “passive” state. If the
channel’s CENTER and DTE bits in CON are both 0, the match simultaneously switches
the channel’s A output from “passive” to “active” state.
Table 706. MCPWM Limit 0 to 2 registers (LIM - 0x400A 0024 (LIM0), 0x400A 0028 (LIM1),
0x400A 002C (LIM2)) bit description
Bit
Symbol
Description
Reset value
31:0
MCLIM
Limit value.
0xFFFF FFFF
Table 707. MCPWM Match 0 to 2 registers (MAT - addresses 0x400A 0030 (MAT0),
0x400A 0034 (MAT1), 0x400A 0038 (MAT2)) bit description
Bit
Symbol
Description
Reset value
31:0
MCMAT
Match value.
0xFFFF FFFF