STR720 datasheet(310/401 Pages) STMICROELECTRONICS

部件名	STR720

功能描述	ARM720T 16/32-BIT MCU WITH 16K RAM, USB, CAN, 3 TIMERS, ADC, 6 COMMUNICATIONS INTERFACES

PDF	401 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

标志

310 / 401 page

STR720 - EXTENDED FUNCTION TIMER (EFT)

310/401

21.3 Functional Description

21.3.1

Counter

The principal block of the Programmable Timer is a 16-bit counter and its associated 16-bit

registers.

Writing in the Counter Register (CNTR) resets the counter to the FFFCh value.

The timer clock source can be either internal or external selecting ECKEN bit of CR1 register.

When ECKEN = 0, the frequency depends on the prescaler division bits (CC7-CC0) of the

CR2 register.

An overflow occurs when the counter rolls over from FFFFh to 0000h then the TOF bit of the

SR register is set. An interrupt is generated if TOIE bit of the CR2 register is set; if this

condition is false, the interrupt remains pending to be issued as soon as it becomes true.

Clearing the overflow interrupt request is done by a write access to the SR register while the

TOF bit is set with the data bus 13-bit at ‘0’, while all the other bits shall be written to ‘1’ (the

SR register is clear only, so writing a ‘1’ in a bit has no effect: this makes possible to clear a

pending bit without risking to clear a new coming interrupt request from another source).

STR720 数据表(PDF) 310 Page - STMicroelectronics