Input Capture Timer STM

Tja, ich wusste es auch nicht auf Anhieb, aber warum schaust Du nicht ins Datenblatt? Da steht:

IC1F[3:0]:Inputcapture1filter 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 fDTS 0001: fSAMPLING = fCK_INT, N = 2 0010: fSAMPLING = fCK_INT, N = 4 0011: fSAMPLING = fCK_INT, N = 8 0100: fSAMPLING = fDTS / 2, N = 6 0101: fSAMPLING = fDTS / 2, N = 8 0110: fSAMPLING = fDTS / 4, N = 6 0111: fSAMPLING = fDTS / 4, N = 8 1000: fSAMPLING = fDTS / 8, N = 6 1001: fSAMPLING = fDTS / 8, N = 8 1010: fSAMPLING = fDTS / 16, N = 5 1011: fSAMPLING = fDTS / 16, N = 6 1100: fSAMPLING = fDTS / 16, N = 8 1101: fSAMPLING = fDTS / 32, N = 5 1110: fSAMPLING = fDTS / 32, N = 6 1111: fSAMPLING = fDTS / 32, N = 8

D.h. das Signal muss für eine gewisse Zeit anstehen, damit es als gültig erkannt wird. Kürzere Impulse werden einfach ignoriert.