ST72F321 STMICROELECTRONICS [STMicroelectronics], ST72F321 Datasheet - Page 63

• Manufacturer Part Number: ST72F321
• Description: 64/44-PIN 8-BIT MCU WITH 32 TO 60K FLASH/ROM, ADC, FIVE TIMERS, SPI, SCI, I2C INTERFACE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

PWM AUTO-RELOAD TIMER (Cont’d)
Output compare and Time base interrupt
On overflow, the OVF flag of the ARTCSR register
is set and an overflow interrupt request is generat-
ed if the overflow interrupt enable bit, OIE, in the
ARTCSR register, is set. The OVF flag must be re-
set by the user software. This interrupt can be
used as a time base in the application.
Figure 41. External Event Detector Example (3 counts)
f
EXT
COUNTER
=f
COUNTER
OVF
FDh
FEh
ARTARR=FDh
FFh
INTERRUPT
IF OIE=1
FDh
External clock and event detector mode
Using the f
auto-reload timer can be used as an external clock
event detector. In this mode, the ARTARR register
is used to select the n
be counted before setting the OVF flag.
Caution: The external clock function is not availa-
ble in HALT mode. If HALT mode is used in the ap-
plication, prior to executing the HALT instruction,
the counter must be disabled by clearing the TCE
bit in the ARTCSR register to avoid spurious coun-
ter increments.
ARTCSR READ
FEh
EXT
n
EVENT
external prescaler input clock, the
FFh
INTERRUPT
IF OIE=1
= 256 - ARTARR
EVENT
FDh
number of events to
ARTCSR READ
ST72321
t
63/189