ST STM32F412 Reference Manual page 533

RM0402
Input capture mode
Bits 15:12 IC2F: Input capture 2 filter
Bits 11:10 IC2PSC[1:0]: Input capture 2 prescaler
Bits 9:8 CC2S: Capture/compare 2 selection
This bit-field defines the direction of the channel (input/output) as well as the used input.
00: CC2 channel is configured as output.
01: CC2 channel is configured as input, IC2 is mapped on TI2.
10: CC2 channel is configured as input, IC2 is mapped on TI1.
11: CC2 channel is configured as input, IC2 is mapped on TRC. This mode is working only if
an internal trigger input is selected through TS bit (TIMx_SMCR register)
Note: CC2S bits are writable only when the channel is OFF (CC2E = 0 in TIMx_CCER).
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
1000: f
1001: f
1010: f
1011: f
1100: f
1101: f
1110: f
1111: 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: CC1 channel is configured as input, IC1 is mapped on TI2
11: CC1 channel is configured as input, IC1 is mapped on 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).
=f , N=2
SAMPLING CK_INT
=f , N=4
SAMPLING CK_INT
=f , N=8
SAMPLING CK_INT
=f /2, N=6
SAMPLING DTS
=f /2, N=8
SAMPLING DTS
=f /4, N=6
SAMPLING DTS
=f /4, N=8
SAMPLING DTS
=f /8, N=6
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
RM0402 Rev 6
General-purpose timers (TIM2 to TIM5)
DTS
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544