ST STM8S - Page 190

16-bit advanced control timer (TIM1) RM0016
190/449 Doc ID 14587 Rev 8
Bits 3:0 ETF: External trigger filter.
This bitfield defines the frequency used to sample the ETRP signal and the length of the digital filter
applied to it. The digital filter is made of an event counter in which N events are needed to validate a
transition on the output:
0000: No filter, sampling is done at f
MASTER
0001: f
SAMPLING
=f
MASTER
, N = 2
0010: f
SAMPLING
=f
MASTER
, N = 4
0011: f
SAMPLING
=f
MASTER
, N = 8
0100: f
SAMPLING
=f
MASTER
/2, N = 6
0101: f
SAMPLING
=f
MASTER
/2, N = 8
0110: f
SAMPLING
=f
MASTER
/4, N = 6
0111: f
SAMPLING
=f
MASTER
/4, N = 8
1000: f
SAMPLING
=f
MASTER
/8, N = 6
1001: f
SAMPLING
=f
MASTER
/8, N = 8
1010: f
SAMPLING
=f
MASTER
/16, N = 5
1011: f
SAMPLING
=f
MASTER
/16, N = 6
1100: f
SAMPLING
=f
MASTER
/16, N = 8
1101: f
SAMPLING
=f
MASTER
/32, N = 5
1110: f
SAMPLING
=f
MASTER
/32, N = 6
1111: f
SAMPLING
=f
MASTER
/32, N = 8