ST72561AR7 STMicroelectronics, ST72561AR7 Datasheet - Page 66

• Manufacturer Part Number: ST72561AR7
• Description: 8-bit MCU
• Manufacturer: STMicroelectronics

Specifications of ST72561AR7

• Hdflash Endurance: 100 cycles, data retention 40 years at 85°C
• 5 Power Saving Modes: Halt, Auto Wake Up From Halt, Active Halt, Wait and Slow

ST72561
PWM AUTO-RELOAD TIMER (Cont’d)
Input Capture Function
Input Capture mode allows the measurement of
external signal pulse widths through ARTICRx
registers.
Each input capture can generate an interrupt inde-
pendently on a selected input signal transition.
This event is flagged by a set of the corresponding
CFx bits of the Input Capture Control/Status regis-
ter (ARTICCSR).
These input capture interrupts are enabled
through the CIEx bits of the ARTICCSR register.
The active transition (falling or rising edge) is soft-
ware programmable through the CSx bits of the
ARTICCSR register.
The read only input capture registers (ARTICRx)
are used to latch the auto-reload counter value
when a transition is detected on the ARTICx pin
(CFx bit set in ARTICCSR register). After fetching
the interrupt vector, the CFx flags can be read to
identify the interrupt source.
Note: After a capture detection, data transfer in
the ARTICRx register is inhibited until the next
read (clearing the CFx bit).
The timer interrupt remains pending while the CFx
flag is set when the interrupt is enabled (CIEx bit
Figure 45. Input Capture Timing Diagram, f
66/265
ICAP SAMPLED
ARTICx PIN
COUNTER
CFx FLAG
f
COUNTER
f
CPU
01h
02h
xxh
ICAP SAMPLED
03h
COUNTER
04h
set). This means, the ARTICRx register has to be
read at each capture event to clear the CFx flag.
The timing resolution is given by auto-reload coun-
ter cycle time (1/f
Note: During HALT mode, input capture is inhibit-
ed (the ARTICRx is never reloaded) and only the
external interrupt capability can be used.
Note: The ARTICx signal is synchronized on CPU
clock. It takes two rising edges until ARTICRx is
latched with the counter value. Depending on the
prescaler value and the time when the ICAP event
occurs, the value loaded in the ARTICRx register
may be different.
If the counter is clocked with the CPU clock, the
value latched in ARTICRx is always the next coun-
ter value after the event on ARTICx occurred
ure
If the counter clock is prescaled, it depends on the
position of the ARTICx event within the counter cy-
cle
= f
(Figure
CPU
45).
05h
46).
COUNTER
06h
).
05h
INTERRUPT
07h
t
(Fig-