ST STM32G4 Series Reference Manual page 1146

Advanced-control timers (TIM1/TIM8/TIM20)
Bits 7:4 IC1F[3:0]: Input capture 1 filter
This bit-field defines the frequency used to sample tim_ti1 input and the length of the digital filter
applied to tim_ti1. The digital filter is made of an event counter in which N consecutive events are
needed to validate a transition on the output:
0000: No filter, sampling is done at f
0001: f
SAMPLING
0010: f
SAMPLING
0011: f
SAMPLING
0100: f
SAMPLING
0101: f
SAMPLING
0110: f
SAMPLING
0111: f
SAMPLING
1000: f
SAMPLING
1001: f
SAMPLING
1010: f
SAMPLING
1011: f
SAMPLING
1100: f
SAMPLING
1101: f
SAMPLING
1110: f
SAMPLING
1111: f
SAMPLING
Bits 3:2 IC1PSC[1:0]: Input capture 1 prescaler
This bit-field defines the ratio of the prescaler acting on CC1 input (tim_ic1). The prescaler is reset as
soon as CC1E='0' (TIMx_CCER register).
00: no prescaler, capture is done each time an edge is detected on the capture input
01: capture is done once every 2 events
10: capture is done once every 4 events
11: capture is done once every 8 events
Bits 1:0 CC1S[1:0]: Capture/compare 1 Selection
This bit-field defines the direction of the channel (input/output) as well as the used input.
00: CC1 channel is configured as output
01: CC1 channel is configured as input, tim_ic1 is mapped on tim_ti1
10: CC1 channel is configured as input, tim_ic1 is mapped on tim_ti2
11: CC1 channel is configured as input, tim_ic1 is mapped on tim_trc. This mode is working only if an
internal trigger input is selected through TS bit (TIMx_SMCR register)
Note: CC1S bits are writable only when the channel is OFF (CC1E = '0' in TIMx_CCER).
27.6.8 TIMx capture/compare mode register 1 [alternate]
(TIMx_CCMR1)(x = 1, 8, 20)
Address offset: 0x018
Reset value: 0x0000 0000
The same register can be used for output compare mode (this section) or for input capture
mode (previous section). The direction of a channel is defined by configuring the
corresponding CCxS bits. All the other bits of this register have a different function for input
capture and for output compare modes. It is possible to combine both modes independently
(e.g. channel 1 in input capture mode and channel 2 in output compare mode).
1146/2083
DTS
=f , N=2
tim_ker_ck
=f , N=4
tim_ker_ck
=f , N=8
tim_ker_ck
=f /2, N=6
DTS
=f /2, N=8
DTS
=f /4, N=6
DTS
=f /4, N=8
DTS
=f /8, N=6
DTS
=f /8, N=8
DTS
=f /16, N=5
DTS
=f /16, N=6
DTS
=f /16, N=8
DTS
=f /32, N=5
DTS
=f /32, N=6
DTS
=f /32, N=8
DTS
RM0440 Rev 1
RM0440