ST STM32WL55JC Reference Manual page 788

Advanced-control timer (TIM1)
Bits 13:12 ETPS[1:0]: External trigger prescaler
External trigger signal ETRP frequency must be at most 1/4 of f
prescaler can be enabled to reduce ETRP frequency. It is useful when inputting fast external
clocks.
00: Prescaler OFF
01: ETRP frequency divided by 2
10: ETRP frequency divided by 4
11: ETRP frequency divided by 8
Bits 11:8 ETF[3:0]: External trigger filter
This bit-field then defines the frequency used to sample ETRP signal and the length of the
digital filter applied to ETRP. 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
Bit 7 MSM: Master/slave mode
0: No action
1: The effect of an event on the trigger input (TRGI) is delayed to allow a perfect
Bits 21, 20, 6, 5, 4 TS[4:0]: Trigger selection
This bit-field selects the trigger input to be used to synchronize the counter.
00000: Internal Trigger 0 (ITR0)
00001: Internal Trigger 1 (ITR1)
00010: Internal Trigger 2 (ITR2)
00011: Internal Trigger 3 (ITR3)
00100: TI1 Edge Detector (TI1F_ED)
00101: Filtered Timer Input 1 (TI1FP1)
00110: Filtered Timer Input 2 (TI2FP2)
00111: External Trigger input (ETRF)
Others: Reserved
See
meaning for each Timer.
Note: These bits must be changed only when they are not used (e.g. when SMS=000) to
Bit 3 OCCS: OCREF clear selection
This bit is used to select the OCREF clear source.
0: OCREF_CLR_INT is connected to the OCREF_CLR input
1: OCREF_CLR_INT is connected to ETRF
788/1454
=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
synchronization between the current timer and its slaves (through TRGO). It is useful if
we want to synchronize several timers on a single external event.
Table 179: TIM1 internal trigger connection on page 789
avoid wrong edge detections at the transition.
DTS
RM0453 Rev 2
RM0453
frequency. A
CK_INT
for more details on ITRx