ST72215G2 STMicroelectronics, ST72215G2 Datasheet - Page 46

• Manufacturer Part Number: ST72215G2
• Description: 8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY,ADC, 16-BIT TIMERS, SPI, I2C INTERFACES
• Manufacturer: STMicroelectronics

Specifications of ST72215G2

• Emulation Voltage: 5.5 V

ST72104Gx, ST72215Gx, ST72216Gx, ST72254Gx
16-BIT TIMER (Cont’d)
11.2.3.3 Input Capture
In this section, the index, i, may be 1 or 2 because
there are 2 input capture functions in the 16-bit
timer.
The two input capture 16-bit registers (IC1R and
IC2R) are used to latch the value of the free run-
ning counter after a transition is detected by the
ICAPi pin (see
The ICiR register is a read-only register.
The active transition is software programmable
through the IEDGi bit of Control Registers (CRi).
Timing resolution is one count of the free running
counter: (
Procedure:
To use the input capture function, select the fol-
lowing in the CR2 register:
– Select the timer clock (CC[1:0]) (see
– Select the edge of the active transition on the
And select the following in the CR1 register:
– Set the ICIE bit to generate an interrupt after an
– Select the edge of the active transition on the
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ICAP2 pin with the IEDG2 bit (the ICAP2 pin
must be configured as a floating input or input
with pull-up without interrupt if this configuration
is available).
input capture coming from either the ICAP1 pin
or the ICAP2 pin
ICAP1 pin with the IEDG1 bit (the ICAP1 pin
must be configured as a floating input or input
with pull-up without interrupt if this configuration
is available).
ICiR
f
CPU
/
Figure
CC[1:0]).
MS Byte
ICiHR
5).
LS Byte
ICiLR
Table
1).
When an input capture occurs:
– The ICFi bit is set.
– The ICiR register contains the value of the free
– A timer interrupt is generated if the ICIE bit is set
Clearing the Input Capture interrupt request (i.e.
clearing the ICFi bit) is done in two steps:
1. Reading the SR register while the ICFi bit is set.
2. An access (read or write) to the ICiLR register.
Notes:
1. After reading the ICiHR register, the transfer of
2. The ICiR register contains the free running
3. The two input capture functions can be used
4. In One Pulse mode and PWM mode only the
5. The alternate inputs (ICAP1 and ICAP2) are
6. The TOF bit can be used with an interrupt in
running counter on the active transition on the
ICAPi pin (see
and the I bit is cleared in the CC register. Other-
wise, the interrupt remains pending until both
conditions become true.
input capture data is inhibited and ICFi will
never be set until the ICiLR register is also
read.
counter value which corresponds to the most
recent input capture.
together even if the timer also uses the two out-
put compare functions.
input capture 2 function can be used.
always directly connected to the timer. So any
transitions on these pins activate the input cap-
ture function.
Moreover if one of the ICAPi pin is configured
as an input and the second one as an output,
an interrupt can be generated if the user tog-
gles the output pin and if the ICIE bit is set.
This can be avoided if the input capture func-
tion i is disabled by reading the ICiHR (see note
1).
order to measure events that exceed the timer
range (FFFFh).
Figure
6).