RM0440 Rev 4 1183/2126
RM0440 Advanced-control timers (TIM1/TIM8/TIM20)
1226
Bits 16, 2:0 SMS[3:0]: Slave mode selection
When external signals are selected the active edge of the trigger signal (tim_trgi) is linked to
the polarity selected on the external input (see Input Control register and Control Register
description.
0000: Slave mode disabled - if CEN = ‘1’ then the prescaler is clocked directly by the
internal clock.
0001: Quadrature encoder mode 1, x2 mode- Counter counts up/down on tim_ti1fp1 edge
depending on tim_ti2fp2 level.
0010: Quadrature encoder mode 2, x2 mode - Counter counts up/down on tim_ti2fp2 edge
depending on tim_ti1fp1 level.
0011: Quadrature encoder mode 3, x4 mode - Counter counts up/down on both tim_ti1fp1
and tim_ti2fp2 edges depending on the level of the other input.
0100: Reset Mode - Rising edge of the selected trigger input (tim_trgi) reinitializes the
counter and generates an update of the registers.
0101: Gated Mode - The counter clock is enabled when the trigger input (tim_trgi) is high.
The counter stops (but is not reset) as soon as the trigger becomes low. Both start
and stop of the counter are controlled.
0110: Trigger Mode - The counter starts at a rising edge of the trigger tim_trgi (but it is not
reset). Only the start of the counter is controlled.
0111: External Clock Mode 1 - Rising edges of the selected trigger (tim_trgi) clock the
counter.
1000: Combined reset + trigger mode - Rising edge of the selected trigger input (tim_trgi)
reinitializes the counter, generates an update of the registers and starts the counter.
1001: Combined gated + reset mode - The counter clock is enabled when the trigger input
(tim_trgi) is high. The counter stops and is reset) as soon as the trigger becomes low.
Both start and stop of the counter are controlled.
1010: Encoder mode: Clock plus direction, x2 mode.
1011: Encoder mode: Clock plus direction, x1 mode, tim_ti2fp2 edge sensitivity is set by
CC2P
1100: Encoder mode: Directional Clock, x2 mode.
1101: Encoder mode: Directional Clock, x1 mode, tim_ti1fp1 and tim_ti2fp2 edge sensitivity
is set by CC1P and CC2P.
1110: Quadrature encoder mode: x1 mode, counting on tim_ti1fp1 edges only, edge
sensitivity is set by CC1P.
1111: Quadrature encoder mode: x1 mode, counting on tim_ti2fp2 edges only, edge
sensitivity is set by CC2P.
Note: The gated mode must not be used if tim_ti1f_ed is selected as the trigger input
(TS=00100). Indeed, tim_ti1f_ed outputs 1 pulse for each transition on TI1F, whereas
the gated mode checks the level of the trigger signal.
Note: The clock of the slave peripherals (timer, ADC, ...) receiving the tim_trgo or the
tim_trgo2 signals must be enabled prior to receive events from the master timer, and
the clock frequency (prescaler) must not be changed on-the-fly while triggers are
received from the master timer.
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