STM32W108CB datasheet(98/179 Pages) STMICROELECTRONICS

98 / 179 page

General-purpose timers

STM32W108CB, STM32W108HB

98/179

Doc ID 16252 Rev 2

In PWM mode 1, the reference signal OCyREF is low as long as TIMx_CNT > TIMx_CCRy,

otherwise it becomes high. If the compare value in TIMx_CCRy is greater than the auto-

reload value in TIMx_ARR, then OCyREF is held at 1. Zero-percent PWM is not possible in

this mode.

PWM center-aligned mode

Center-aligned mode is active except when the TIM_CMS bits in the TIMx_CR1 register are

00 (all configurations where TIM_CMS is non-zero have the same effect on the

OCyREF/OCy signals). The compare flag is set when the counter counts up, when it counts

down, or when it counts up and down, depending on the TIM_CMS bits configuration. The

direction bit (TIM_DIR) in the TIMx_CR1 register is updated by hardware and must not be

changed by software. Refer to Center-aligned mode (up/down counting) on page 86 for

more information.

Figure 32 shows some center-aligned PWM waveforms in an example where:

●

TIMx_ARR = 8,

●

PWM mode is the PWM mode 1,

●

The output compare flag is set when the counter counts down corresponding to the

center-aligned mode 1 selected for TIM_CMS = 01 in the TIMx_CR1 register.

Figure 32.

Center-aligned PWM waveforms (ARR = 8)

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