General purpose timer (TIMx) UM0306
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Figure 98. Capture/compare channel 1 main circuit
Figure 99. Output stage of capture/compare channel (channel 1)
The capture/compare block is made of one preload register and one shadow register. Write
and read always access the preload register.
In capture mode, captures are actually done in the shadow register, which is copied into the
preload register.
In compare mode, the content of the preload register is copied into the shadow register
which is compared to the counter.
13.4.5 Input capture mode
In Input capture mode, the Capture/Compare Registers (TIMx_CCRx) are used to latch the
value of the counter after a transition detected by the corresponding ICx signal. When a
capture occurs, the corresponding CCXIF flag (TIMx_SR register) is set and an interrupt or
a DMA request can be sent if they are enabled. If a capture occurs while the CCxIF flag was
already high, then the over-capture flag CCxOF (TIMx_SR register) is set. CCxIF can be
CC1E
Capture/Compare Shadow Register
comparator
Capture/Compare Preload Register
Counter
ic1ps
CC1S[0]
CC1S[1]
capture
input
mode
S
R
read CCR1H
read CCR1L
read_in_progress
capture_transfer
CC1S[0]
CC1S[1]
S
R
write CCR1H
write CCR1L
write_in_progress
output
mode
UEV
OC1PE
(from time
compare_transfer
APB Bus
8
8
high
low
(if 16-bit)
MCU-PERIPHERAL INTERFACE
TIMx_CCMR1
OC1PE
base unit)
CNT>CCR1
CNT=CCR1
TIMx_EGR
CC1G
Output Mode
CNT > CCR1
CNT = CCR1
Controller
TIMx_CCMR1
OC1M[2:0]
oc1ref
0
1
CC1P
TIMx_CCER
Output
Enable
Circuit
OC1
CC1E
TIMx_CCER
To the master mode
controller
ETRF