UPD784938 Datasheet, PDF (400/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 15 PWM OUTPUT UNIT
15.3.2 PWM pulse output enabling/disabling
When PWM pulses are output, the ENn (n = 0, 1) bits of the PMC register are set (to 1) after data is set in the PWM
prescaler register (PWPR) and PWM modulo register (PWMn: n = 0, 1). As a result, PWM pulses with the active level
specified by ALVn (n = 0, 1) bit of the PWM control register (PWMC) are output from the PWM output pin.
When the ENn bits of the PWMC are cleared (to 0), the PWM output unit immediately stops the PWM output operation.
15.3.3 PWM pulse active level specification
The ALVn (n = 0, 1) bit of the PWM control register (PWMC) specify the active level of PWM pulses output from the
PWM output pins.
When ALVn bit is set (to 1), active-high level pulses are output, and when cleared (to 0), active-low level pulses are output.
When ALVn bit is rewritten, the PWM active level changes immediately. PWM output active level setting and pin states
are shown in Figure 15-5.
Figure 15-5 shows the case where ALVn bit is switched when the ENn (n = 0, 1) bit of the PWMC is set (to 1) and PWM
output is enabled.
The pin state does not change if ALVn is rewritten when ENn bit is in the cleared (to 0) state.
Figure 15-5. PWM Output Active Level Setting
ALVn
(Active-high)
(Active-low)
PWMn
Remark ENn = 1 (n = 0, 1)
(ALVn bit rewrite)
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Preliminary User’s Manual U13987EJ1V0UM00