ST STM32F423 Reference Manual page 636

General-purpose timers (TIM9 to TIM14)
Input capture mode
Bits 15:8 Reserved, must be kept at reset value.
Bits 7:4 IC1F: Input capture 1 filter
This bit-field defines the frequency used to sample TI1 input and the length of the digital filter
applied to 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
0010: f
0011: f
0100: f
0101: f
0110: f
0111: f
Bits 3:2 IC1PSC: Input capture 1 prescaler
This bit-field defines the ratio of the prescaler acting on CC1 input (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: 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, IC1 is mapped on TI1
10: Reserved
11: Reserved
Note: CC1S bits are writable only when the channel is OFF (CC1E = 0 in TIMx_CCER).
636/1324
=f , N=21001: f
SAMPLING CK_INT
=f , N=41010: f
SAMPLING CK_INT
=f , N=81011: f
SAMPLING CK_INT
=f /2, N=61100: f
SAMPLING DTS
=f /2, N=81101: f
SAMPLING DTS
=f /4, N=61110: f
SAMPLING DTS
=f /4, N=81111: f
SAMPLING DTS
RM0430 Rev 8
1000: f =f
DTS SAMPLING DTS
=f /8, N=8
SAMPLING DTS
=f /16, N=5
SAMPLING DTS
=f /16, N=6
SAMPLING DTS
=f /16, N=8
SAMPLING DTS
=f /32, N=5
SAMPLING DTS
=f /32, N=6
SAMPLING DTS
=f /32, N=8
SAMPLING DTS
RM0430
/8, N=6