STM8S datasheet(154/467 Pages) STMICROELECTRONICS

No. de pieza	STM8S

Descripción Electrónicos	STM8S Series and STM8AF Series 8-bit microcontrollers

PDF	467 Pages

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Fabricante Electrónico	STMICROELECTRONICS [STMicroelectronics]

Página de inicio	http://www.st.com

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16-bit advanced control timer (TIM1)

RM0016

154/467

DocID14587 Rev 14

17.4.4

External clock source mode 2

The counter can count at each rising or falling edge on the ETR. This mode is selected by

writing ECE = 1 in the TIM1_ETR register.

The Figure 47 gives an overview of the external trigger input block.

Figure 47. External trigger input block diagram

Procedure

Use the following procedure to configure the up-counter and, for example, to count once

every two rising edges on the ETR:

As no filter is needed in this example, write ETF[3:0] = 0000 in the TIM1_ETR register.

Set the prescaler by writing ETPS[1:0] = 01 in the TIM1_ETR register.

Select rising edge detection on the ETR pin by writing ETP = 0 in the TIM1_ETR

Enable external clock mode 2 by writing ECE = 1 in the TIM1_ETR register.

Enable the counter by writing CEN = 1 in the TIM1_CR1 register.

The counter counts once every two ETR rising edges.

The delay between the rising edge on the ETR and the actual reset of the counter is due to

the resynchronization circuit on the external trigger signal (ETRP).

Figure 48. Control circuit in external clock mode 2

STM8S Datasheet(PDF) 154 Page - STMicroelectronics