ST72C171 datasheet(72/152 Pages) STMICROELECTRONICS

No de pièce	ST72C171

Description	8-BIT MCU with 8K FLASH, ADC, WDG, SPI, SCI, TIMERS SPGAs Software Programmable Gain Amplifiers, OP-AMP

PDF	152 Pages

Scroll/Zoom	100%

Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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ST72C171

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PWM AUTO-RELOAD TIMER (Cont’d)

Output compare and Time base interrupt

On overflow, the OVF flag of the CSR register is

set and an overflow interrupt request is generated

if the overflow interrupt enable bit, OIE, in the CSR

user software. This interrupt can be used as a time

base in the application.

External clock and event detector mode

Using the fEXT external prescaler input clock, the

auto-reload timer can be used as an external clock

event detector. In this mode, the ARR register is

used to select the nEVENT number of events to be

counted before setting the OVF flag.

nEVENT = 256 - ARR

When entering HALT mode while fEXT is selected,

all the timer control registers are frozen but the

counter continues to increment. If the OIE bit is

set, the next overflow of the counter will generate

an interrupt which wakes up the MCU.

Figure 45. External Event Detector Example (3 counts)

COUNTER

FDh

FEh

FFh

FDh

OVF

CSR READ

INTERRUPT

ARR=FDh

fEXT=fCOUNTER

FEh

FFh

FDh

IF OIE=1

INTERRUPT

IF OIE=1

CSR READ

ST72C171 Fiches technique(PDF) 72 Page - STMicroelectronics