STM8S datasheet(177/467 Pages) STMICROELECTRONICS

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RM0016

16-bit advanced control timer (TIM1)

261

One-pulse mode

One-pulse mode (OPM) is a particular case of the previous modes. It allows the counter to

be started in response to a stimulus and to generate a pulse with a programmable length

after a programmable delay.

Starting the counter can be controlled through the clock/trigger controller. Generating the

waveform can be done in output compare mode or PWM mode. Select one-pulse mode by

setting the OPM bit in the TIM1_CR1 register. This makes the counter stop automatically at

the next UEV.

A pulse can be correctly generated only if the compare value is different from the counter

initial value. Before starting (when the timer is waiting for the trigger), the configuration must

be:

•

In up-counting: CNT< CCRi

≤ ARR (in particular, 0 < CCRi),

•

In down-counting: CNT> CCRi

Figure 72. Example of one-pulse mode

Example

This example shows how to generate a positive pulse on OC1 with a length of tPULSE and

after a delay of tDELAY as soon as a positive edge is detected on the TI2 input pin.

Follow the procedure below to use IC2 as trigger 1:

•

Map IC2 on TI2 by writing CC2S = 01 in the TIM1_CCMR2 register

•

IC2 must detect a rising edge, so write CC2P = 0 in the TIM1_CCER1 register

•

Configure IC2 as trigger for the clock/trigger controller (TRGI) by writing TS = 110 in the

TIM1_SMCR register.

•

IC2 is used to start the counter by writing SMS to 110 in the TIM1_SMCR register

(trigger mode).

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