17. General-purpose timers (TIM12/13/14)

17.1 TIM12/13/14 introduction

The TIM12/13/14 general-purpose timers consist of a 16-bit auto-reload counter driven by a programmable prescaler.

They may be used for a variety of purposes, including measuring the pulse lengths of input signals (input capture) or generating output waveforms (output compare, PWM).

Pulse lengths and waveform periods can be modulated from a few microseconds to several milliseconds using the timer prescaler and the RCC clock controller prescalers.

The TIM12/13/14 timers are completely independent, and do not share any resources. They can be synchronized together as described in Section 17.4.12 .

17.2 TIM12/13/14 main features

17.2.1 TIM12 main features

The features of the TIM12 general-purpose timer include:

• • 16-bit auto-reload upcounter (in medium density devices)
• • 16-bit programmable prescaler used to divide the counter clock frequency by any factor between 1 and 65535 (can be changed “on the fly”)
• • Up to 2 independent channels for:
  • – Input capture
  • – Output compare
  • – PWM generation (edge-aligned mode)
  • – One-pulse mode output
• • Synchronization circuit to control the timer with external signals and to interconnect several timers together
• • Interrupt generation on the following events:
  • – Update: counter overflow, counter initialization (by software or internal trigger)
  • – Trigger event (counter start, stop, initialization or count by internal trigger)
  • – Input capture
  • – Output compare

Figure 100. General-purpose timer block diagram (TIM12)

17.3 TIM13/TIM14 main features

The features of general-purpose timers TIM13/TIM14 include:

• • 16-bit auto-reload upcounter
• • 16-bit programmable prescaler used to divide the counter clock frequency by any factor between 1 and 65535 (can be changed “on the fly”)
• • independent channel for:
  • – Input capture
  • – Output compare
  • – PWM generation (edge-aligned mode)
• • Interrupt generation on the following events:
  • – Update: counter overflow, counter initialization (by software)
  • – Input capture
  • – Output compare

Figure 101. General-purpose timer block diagram (TIM13/14)

17.4 TIM12/13/14 functional description

17.4.1 Time-base unit

The main block of the timer is a 16-bit counter with its related auto-reload register. The counter counts up. The counter clock can be divided by a prescaler.

The counter, the auto-reload register and the prescaler register can be written or read by software. This is true even when the counter is running.

The time-base unit includes:

• • Counter register (TIMx_CNT)
• • Prescaler register (TIMx_PSC)
• • Auto-reload register (TIMx_ARR)

The auto-reload register is preloaded. Writing to or reading from the auto-reload register accesses the preload register. The content of the preload register are transferred into the shadow register permanently or at each update event (UEV), depending on the auto-reload preload enable bit (ARPE) in TIMx_CR1 register. The update event is sent when the counter reaches the overflow and if the UDIS bit equals 0 in the TIMx_CR1 register. It can also be generated by software. The generation of the update event is described in detailed for each configuration.

The counter is clocked by the prescaler output CK_CNT, which is enabled only when the counter enable bit (CEN) in TIMx_CR1 register is set (refer also to the slave mode controller description to get more details on counter enabling).

Note that the counter starts counting 1 clock cycle after setting the CEN bit in the TIMx_CR1 register.

Prescaler description

The prescaler can divide the counter clock frequency by any factor between 1 and 65536. It is based on a 16-bit counter controlled through a 16-bit register (in the TIMx_PSC register). It can be changed on the fly as this control register is buffered. The new prescaler ratio is taken into account at the next update event.

Figure 103 and Figure 104 give some examples of the counter behavior when the prescaler ratio is changed on the fly.

Figure 102. Counter timing diagram with prescaler division change from 1 to 2

Figure 103. Counter timing diagram with prescaler division change from 1 to 4

17.4.2 Counter modes

Upcounting mode

In upcounting mode, the counter counts from 0 to the auto-reload value (content of the TIMx_ARR register), then restarts from 0 and generates a counter overflow event.

Setting the UG bit in the TIMx_EGR register (by software or by using the slave mode controller on TIM12) also generates an update event.

The UEV event can be disabled by software by setting the UDIS bit in the TIMx_CR1 register. This is to avoid updating the shadow registers while writing new values in the preload registers. Then no update event occurs until the UDIS bit has been written to 0. However, the counter restarts from 0, as well as the counter of the prescaler (but the prescale rate does not change). In addition, if the URS bit (update request selection) in TIMx_CR1 register is set, setting the UG bit generates an update event UEV but without setting the UIF flag (thus no interrupt is sent). This is to avoid generating both update and capture interrupts when clearing the counter on the capture event.

When an update event occurs, all the registers are updated and the update flag (UIF bit in TIMx_SR register) is set (depending on the URS bit):

• • The auto-reload shadow register is updated with the preload value (TIMx_ARR),
• • The buffer of the prescaler is reloaded with the preload value (content of the TIMx_PSC register).

The following figures show some examples of the counter behavior for different clock frequencies when TIMx_ARR=0x36.

Figure 104. Counter timing diagram, internal clock divided by 1

Figure 105. Counter timing diagram, internal clock divided by 2

Figure 106. Counter timing diagram, internal clock divided by 4

Figure 107. Counter timing diagram, internal clock divided by N

Figure 108. Counter timing diagram, update event when ARPE=0 (TIMx_ARR not preloaded)

Figure 109. Counter timing diagram, update event when ARPE=1 (TIMx_ARR preloaded)

17.4.3 Clock selection

The counter clock can be provided by the following clock sources:

• • Internal clock (CK_INT)
• • External clock mode1 (for TIM12 ): external input pin (TIx)
• • Internal trigger inputs (ITRx) (for TIM12 ): connecting the trigger output from another timer. Refer to Section : Using one timer as prescaler for another timer for more details.

Internal clock source (CK_INT)

The internal clock source is the default clock source for TIM13/TIM14.

For TIM12, the internal clock source is selected when the slave mode controller is disabled (SMS='000'). The CEN bit in the TIMx_CR1 register and the UG bit in the TIMx_EGR register are then used as control bits and can be changed only by software (except for UG which remains cleared). As soon as the CEN bit is programmed to 1, the prescaler is clocked by the internal clock CK_INT.

Figure 110 shows the behavior of the control circuit and the upcounter in normal mode, without prescaler.

Figure 110. Control circuit in normal mode, internal clock divided by 1

External clock source mode 1(TIM12)

This mode is selected when SMS='111' in the TIMx_SMCR register. The counter can count at each rising or falling edge on a selected input.

Figure 111. TI2 external clock connection example

For example, to configure the upcounter to count in response to a rising edge on the TI2 input, use the following procedure:

1. 1. Configure channel 2 to detect rising edges on the TI2 input by writing CC2S = '01' in the TIMx_CCMR1 register.
2. 2. Configure the input filter duration by writing the IC2F[3:0] bits in the TIMx_CCMR1 register (if no filter is needed, keep IC2F='0000').
3. 3. Select the rising edge polarity by writing CC2P='0' and CC2NP='0' in the TIMx_CCER register.
4. 4. Configure the timer in external clock mode 1 by writing SMS='111' in the TIMx_SMCR register.
5. 5. Select TI2 as the trigger input source by writing TS='110' in the TIMx_SMCR register.
6. 6. Enable the counter by writing CEN='1' in the TIMx_CR1 register.

Note: The capture prescaler is not used for triggering, so it does not need to be configured.

When a rising edge occurs on TI2, the counter counts once and the TIF flag is set.

The delay between the rising edge on TI2 and the actual clock of the counter is due to the resynchronization circuit on TI2 input.

Figure 112. Control circuit in external clock mode 1

17.4.4 Capture/compare channels

Each of the Capture/Compare channels is built around a capture/compare register (including a shadow register), an input stage for capture (with digital filter, multiplexing and prescaler) and an output stage (with comparator and output control).

Figure 113: Capture/compare channel (example: channel 1 input stage), Figure 114: Capture/compare channel 1 main circuit and Figure 115: Output stage of capture/compare channel (channel 1) provide an overview.

The input stage samples the corresponding TIx input to generate a filtered signal TIxF. Then, an edge detector with polarity selection generates a signal (TIxFPx) which can be used as trigger input by the slave mode controller or as the capture command. It is prescaled before the capture register (ICxPS).

Figure 113. Capture/compare channel (example: channel 1 input stage)

The output stage generates an intermediate waveform which is then used for reference: OCxRef (active high). The polarity acts at the end of the chain.

Figure 114. Capture/compare channel 1 main circuit

Figure 115. Output stage of capture/compare channel (channel 1)

The capture/compare block is made of one preload register and one shadow register. Write and read always access the preload register.

In capture mode, captures are actually done in the shadow register, which is copied into the preload register.

In compare mode, the content of the preload register is copied into the shadow register which is compared to the counter.

17.4.5 Input capture mode

In Input capture mode, the Capture/Compare Registers (TIMx_CCRx) are used to latch the value of the counter after a transition detected by the corresponding ICx signal. When a capture occurs, the corresponding CCxIF flag (TIMx_SR register) is set and an interrupt or a DMA request can be sent if they are enabled. If a capture occurs while the CCxIF flag was already high, then the over-capture flag CCxOF (TIMx_SR register) is set. CCxIF can be cleared by software by writing it to '0' or by reading the captured data stored in the TIMx_CCRx register. CCxOF is cleared when it is written with 0.

The following example shows how to capture the counter value in TIMx_CCR1 when TI1 input rises. To do this, use the following procedure:

1. 1. Select the active input: TIMx_CCR1 must be linked to the TI1 input, so write the CC1S bits to '01' in the TIMx_CCMR1 register. As soon as CC1S becomes different from '00', the channel is configured in input mode and the TIMx_CCR1 register becomes read-only.
2. 2. Program the appropriate input filter duration in relation with the signal connected to the timer (when the input is one of the TIx (ICxF bits in the TIMx_CCMRx register). Let's imagine that, when toggling, the input signal is not stable during at most 5 internal clock cycles. We must program a filter duration longer than these 5 clock cycles. We can validate a transition on TI1 when 8 consecutive samples with the new level have been

detected (sampled at \( f_{DTS} \) frequency). Then write IC1F bits to '0011' in the TIMx_CCMR1 register.

1. 3. Select the edge of the active transition on the TI1 channel by programming CC1P and CC1NP bits to '00' in the TIMx_CCER register (rising edge in this case).
2. 4. Program the input prescaler. In our example, we wish the capture to be performed at each valid transition, so the prescaler is disabled (write IC1PS bits to '00' in the TIMx_CCMR1 register).
3. 5. Enable capture from the counter into the capture register by setting the CC1E bit in the TIMx_CCER register.
4. 6. If needed, enable the related interrupt request by setting the CC1IE bit in the TIMx_DIER register.

When an input capture occurs:

• • The TIMx_CCR1 register gets the value of the counter on the active transition.
• • CC1IF flag is set (interrupt flag). CC1OF is also set if at least two consecutive captures occurred whereas the flag was not cleared.
• • An interrupt is generated depending on the CC1IE bit.

In order to handle the overcapture, it is recommended to read the data before the overcapture flag. This is to avoid missing an overcapture which could happen after reading the flag and before reading the data.

Note: IC interrupt requests can be generated by software by setting the corresponding CCxG bit in the TIMx_EGR register.

17.4.6 PWM input mode (only for TIM12)

This mode is a particular case of input capture mode. The procedure is the same except:

• • Two ICx signals are mapped on the same TIx input.
• • These 2 ICx signals are active on edges with opposite polarity.
• • One of the two TIxFP signals is selected as trigger input and the slave mode controller is configured in reset mode.

For example, one can measure the period (in TIMx_CCR1 register) and the duty cycle (in TIMx_CCR2 register) of the PWM applied on TI1 using the following procedure (depending on CK_INT frequency and prescaler value):

1. 1. Select the active input for TIMx_CCR1: write the CC1S bits to '01' in the TIMx_CCMR1 register (TI1 selected).
2. 2. Select the active polarity for TI1FP1 (used both for capture in TIMx_CCR1 and counter clear): program the CC1P and CC1NP bits to '00' (active on rising edge).
3. 3. Select the active input for TIMx_CCR2: write the CC2S bits to '10' in the TIMx_CCMR1 register (TI1 selected).
4. 4. Select the active polarity for TI1FP2 (used for capture in TIMx_CCR2): program the CC2P and CC2NP bits to '11' (active on falling edge).
5. 5. Select the valid trigger input: write the TS bits to '101' in the TIMx_SMCR register (TI1FP1 selected).
6. 6. Configure the slave mode controller in reset mode: write the SMS bits to '100' in the TIMx_SMCR register.
7. 7. Enable the captures: write the CC1E and CC2E bits to '1' in the TIMx_CCER register.

Figure 116. PWM input mode timing

1. 1. The PWM input mode can be used only with the TIMx_CH1/TIMx_CH2 signals due to the fact that only TI1FP1 and TI2FP2 are connected to the slave mode controller.

17.4.7 Forced output mode

In output mode (CCxS bits = '00' in the TIMx_CCMRx register), each output compare signal (OCxREF and then OCx) can be forced to active or inactive level directly by software, independently of any comparison between the output compare register and the counter.

To force an output compare signal (OCXREF/OCx) to its active level, one just needs to write '101' in the OCxM bits in the corresponding TIMx_CCMRx register. Thus OCXREF is forced high (OCxREF is always active high) and OCx get opposite value to CCxP polarity bit.

For example: CCxP='0' (OCx active high) => OCx is forced to high level.

The OCxREF signal can be forced low by writing the OCxM bits to '100' in the TIMx_CCMRx register.

Anyway, the comparison between the TIMx_CCRx shadow register and the counter is still performed and allows the flag to be set. Interrupt requests can be sent accordingly. This is described in the output compare mode section below.

17.4.8 Output compare mode

This function is used to control an output waveform or indicating when a period of time has elapsed.

When a match is found between the capture/compare register and the counter, the output compare function:

1. 1. Assigns the corresponding output pin to a programmable value defined by the output compare mode (OCxM bits in the TIMx_CCMRx register) and the output polarity (CCxP bit in the TIMx_CCER register). The output pin can keep its level (OCxM='000'), be set active (OCxM='001'), be set inactive (OCxM='010') or can toggle (OCxM='011') on match.
2. 2. Sets a flag in the interrupt status register (CCxIF bit in the TIMx_SR register).
3. 3. Generates an interrupt if the corresponding interrupt mask is set (CCxIE bit in the TIMx_DIER register).

The TIMx_CCRx registers can be programmed with or without preload registers using the OCxPE bit in the TIMx_CCMRx register.

In output compare mode, the update event UEV has no effect on OCxREF and OCx output. The timing resolution is one count of the counter. Output compare mode can also be used to output a single pulse (in One-pulse mode).

Procedure:

1. 1. Select the counter clock (internal, external, prescaler).
2. 2. Write the desired data in the TIMx_ARR and TIMx_CCRx registers.
3. 3. Set the CCxIE bit if an interrupt request is to be generated.
4. 4. Select the output mode. For example:
   • – Write OCxM = '011' to toggle OCx output pin when CNT matches CCRx
   • – Write OCxPE = '0' to disable preload register
   • – Write CCxP = '0' to select active high polarity
   • – Write CCxE = '1' to enable the output
5. 5. Enable the counter by setting the CEN bit in the TIMx_CR1 register.

The TIMx_CCRx register can be updated at any time by software to control the output waveform, provided that the preload register is not enabled (OCxPE='0', else TIMx_CCRx shadow register is updated only at the next update event UEV). An example is given in Figure 117 .

Figure 117. Output compare mode, toggle on OC1

17.4.9 PWM mode

Pulse Width Modulation mode allows to generate a signal with a frequency determined by the value of the TIMx_ARR register and a duty cycle determined by the value of the TIMx_CCRx register.

The PWM mode can be selected independently on each channel (one PWM per OCx output) by writing '110' (PWM mode 1) or '111' (PWM mode 2) in the OCxM bits in the TIMx_CCMRx register. The corresponding preload register must be enabled by setting the OCxPE bit in the TIMx_CCMRx register, and eventually the auto-reload preload register (in upcounting or center-aligned modes) by setting the ARPE bit in the TIMx_CR1 register.

As the preload registers are transferred to the shadow registers only when an update event occurs, before starting the counter, all registers must be initialized by setting the UG bit in the TIMx_EGR register.

The OCx polarity is software programmable using the CCxP bit in the TIMx_CCER register. It can be programmed as active high or active low. The OCx output is enabled by the CCxE bit in the TIMx_CCER register. Refer to the TIMx_CCERx register description for more details.

In PWM mode (1 or 2), TIMx_CNT and TIMx_CCRx are always compared to determine whether \( TIMx\_CNT \leq TIMx\_CCRx \) .

The timer is able to generate PWM in edge-aligned mode only since the counter is upcounting.

PWM edge-aligned mode

In the following example, we consider PWM mode 1. The reference PWM signal OCxREF is high as long as \( TIMx\_CNT < TIMx\_CCRx \) else it becomes low. If the compare value in TIMx_CCRx is greater than the auto-reload value (in TIMx_ARR) then OCxREF is held at '1'. If the compare value is 0 then OCxRef is held at '0'. Figure 118 shows some edge-aligned PWM waveforms in an example where TIMx_ARR=8.

Figure 118. Edge-aligned PWM waveforms (ARR=8)

17.4.10 One-pulse mode (only for TIM12)

One-pulse mode (OPM) is a particular case of the previous modes. It allows the counter to be started in response to a stimulus and to generate a pulse with a programmable length after a programmable delay.

Starting the counter can be controlled through the slave mode controller. Generating the waveform can be done in output compare mode or PWM mode. One-pulse mode is selected by setting the OPM bit in the TIMx_CR1 register. This makes the counter stop automatically at the next update event UEV.

A pulse can be correctly generated only if the compare value is different from the counter initial value. Before starting (when the timer is waiting for the trigger), the configuration must be as follows:

Figure 119. Example of one pulse mode

For example one may want to generate a positive pulse on OC1 with a length of \( t_{\text{PULSE}} \) and after a delay of \( t_{\text{DELAY}} \) as soon as a positive edge is detected on the TI2 input pin.

Use TI2FP2 as trigger 1:

1. 1. Map TI2FP2 to TI2 by writing CC2S='01' in the TIMx_CCMR1 register.
2. 2. TI2FP2 must detect a rising edge, write CC2P='0' and CC2NP = '0' in the TIMx_CCER register.
3. 3. Configure TI2FP2 as trigger for the slave mode controller (TRGI) by writing TS='110' in the TIMx_SMCR register.
4. 4. TI2FP2 is used to start the counter by writing SMS to '110' in the TIMx_SMCR register (trigger mode).

The OPM waveform is defined by writing the compare registers (taking into account the clock frequency and the counter prescaler).

• • The \( t_{\text{DELAY}} \) is defined by the value written in the TIMx_CCR1 register.
• • The \( t_{\text{PULSE}} \) is defined by the difference between the auto-reload value and the compare value (TIMx_ARR - TIMx_CCR1).
• • Let's say one wants to build a waveform with a transition from '0' to '1' when a compare match occurs and a transition from '1' to '0' when the counter reaches the auto-reload value. To do this PWM mode 2 must be enabled by writing OC1M='111' in the TIMx_CCMR1 register. Optionally the preload registers can be enabled by writing OC1PE='1' in the TIMx_CCMR1 register and ARPE in the TIMx_CR1 register. In this case one has to write the compare value in the TIMx_CCR1 register, the auto-reload value in the TIMx_ARR register, generate an update by setting the UG bit and wait for external trigger event on TI2. CC1P is written to '0' in this example.

Since only 1 pulse (Single mode) is needed, a 1 must be written in the OPM bit in the TIMx_CR1 register to stop the counter at the next update event (when the counter rolls over from the auto-reload value back to 0). When OPM bit in the TIMx_CR1 register is set to '0', so the Repetitive Mode is selected.

Particular case: OCx fast enable

In One-pulse mode, the edge detection on TIx input set the CEN bit which enables the counter. Then the comparison between the counter and the compare value makes the output toggle. But several clock cycles are needed for these operations and it limits the minimum delay \( t_{\text{DELAY}} \) min we can get.

If one wants to output a waveform with the minimum delay, the OCxFE bit can be set in the TIMx_CCMRx register. Then OCxRef (and OCx) are forced in response to the stimulus, without taking in account the comparison. Its new level is the same as if a compare match had occurred. OCxFE acts only if the channel is configured in PWM1 or PWM2 mode.

17.4.11 TIM12 external trigger synchronization

The TIM12 timer can be synchronized with an external trigger in several modes: Reset mode, Gated mode and Trigger mode.

Slave mode: Reset mode

The counter and its prescaler can be reinitialized in response to an event on a trigger input. Moreover, if the URS bit from the TIMx_CR1 register is low, an update event UEV is generated. Then all the preloaded registers (TIMx_ARR, TIMx_CCRx) are updated.

In the following example, the upcounter is cleared in response to a rising edge on TI1 input:

1. 1. Configure the channel 1 to detect rising edges on TI1. Configure the input filter duration (in this example, we do not need any filter, so we keep IC1F='0000'). The capture prescaler is not used for triggering, so it does not need to be configured. The CC1S bits select the input capture source only, CC1S = '01' in the TIMx_CCMR1 register. Program CC1P and CC1NP to '00' in TIMx_CCER register to validate the polarity (and detect rising edges only).
2. 2. Configure the timer in reset mode by writing SMS='100' in TIMx_SMCR register. Select TI1 as the input source by writing TS='101' in TIMx_SMCR register.
3. 3. Start the counter by writing CEN='1' in the TIMx_CR1 register.

The counter starts counting on the internal clock, then behaves normally until TI1 rising edge. When TI1 rises, the counter is cleared and restarts from 0. In the meantime, the trigger flag is set (TIF bit in the TIMx_SR register) and an interrupt request can be sent if enabled (depending on the TIE bit in TIMx_DIER register).

The following figure shows this behavior when the auto-reload register TIMx_ARR=0x36. The delay between the rising edge on TI1 and the actual reset of the counter is due to the resynchronization circuit on TI1 input.

Figure 120. Control circuit in reset mode

Slave mode: Gated mode

The counter can be enabled depending on the level of a selected input.

In the following example, the upcounter counts only when TI1 input is low:

1. 1. Configure the channel 1 to detect low levels on TI1. Configure the input filter duration (in this example, we do not need any filter, so we keep IC1F='0000'). The capture prescaler is not used for triggering, so it does not need to be configured. The CC1S bits select the input capture source only, CC1S='01' in TIMx_CCMR1 register. Program CC1P='1' and CC1NP= '0' in TIMx_CCER register to validate the polarity (and detect low level only).
2. 2. Configure the timer in gated mode by writing SMS='101' in TIMx_SMCR register. Select TI1 as the input source by writing TS='101' in TIMx_SMCR register.
3. 3. Enable the counter by writing CEN='1' in the TIMx_CR1 register (in gated mode, the counter doesn't start if CEN='0', whatever is the trigger input level).

The counter starts counting on the internal clock as long as TI1 is low and stops as soon as TI1 becomes high. The TIF flag in the TIMx_SR register is set both when the counter starts or stops.

The delay between the rising edge on TI1 and the actual stop of the counter is due to the resynchronization circuit on TI1 input.

Figure 121. Control circuit in gated mode

Slave mode: Trigger mode

The counter can start in response to an event on a selected input.

In the following example, the upcounter starts in response to a rising edge on TI2 input:

1. 1. Configure the channel 2 to detect rising edges on TI2. Configure the input filter duration (in this example, we do not need any filter, so we keep IC2F='0000'). The capture prescaler is not used for triggering, so it does not need to be configured. The CC2S bits are configured to select the input capture source only, CC2S='01' in TIMx_CCMR1 register. Program CC2P='1' and CC2NP='0' in TIMx_CCER register to validate the polarity (and detect low level only).
2. 2. Configure the timer in trigger mode by writing SMS='110' in TIMx_SMCR register. Select TI2 as the input source by writing TS='110' in TIMx_SMCR register.

When a rising edge occurs on TI2, the counter starts counting on the internal clock and the TIF flag is set.

The delay between the rising edge on TI2 and the actual start of the counter is due to the resynchronization circuit on TI2 input.

Figure 122. Control circuit in trigger mode

17.4.12 Timer synchronization (TIM12)

The TIM timers are linked together internally for timer synchronization or chaining. Refer to Section 16.3.15: Timer synchronization on page 338 for details.

17.4.13 Debug mode

When the microcontroller enters debug mode (Cortex ^® -M4 with FPU core halted), the TIMx counter either continues to work normally or stops, depending on DBG_TIMx_STOP configuration bit in DBG module. For more details, refer to Section 31.16.2: Debug support for timers, watchdog, bxCAN and I ² C .

17.5 TIM12 registers

Refer to Section 1.2 on page 36 for a list of abbreviations used in register descriptions.

The peripheral registers have to be written by half-words (16 bits) or words (32 bits). Read accesses can be done by bytes (8 bits), half-words (16 bits) or words (32 bits).

17.5.1 TIM12 control register 1 (TIMx_CR1)

Address offset: 0x00

Reset value: 0x0000

Bits 15:10 Reserved, must be kept at reset value.

Bits 9:8 CKD : Clock division

This bit-field indicates the division ratio between the timer clock (CK_INT) frequency and sampling clock used by the digital filters (TIx),

00: \( t_{DTS} = t_{CK\_INT} \)

01: \( t_{DTS} = 2 \times t_{CK\_INT} \)

10: \( t_{DTS} = 4 \times t_{CK\_INT} \)

11: Reserved

Bit 7 ARPE : Auto-reload preload enable

0: TIMx_ARR register is not buffered.

1: TIMx_ARR register is buffered.

Bits 6:4 Reserved, must be kept at reset value.

Bit 3 OPM : One-pulse mode

0: Counter is not stopped on the update event

1: Counter stops counting on the next update event (clearing the CEN bit).

Bit 2 URS : Update request source

This bit is set and cleared by software to select the UEV event sources.

0: Any of the following events generates an update interrupt if enabled:

• – Counter overflow
• – Setting the UG bit

1: Only counter overflow generates an update interrupt if enabled.

Bit 1 UDIS : Update disable

This bit is set and cleared by software to enable/disable update event (UEV) generation.

0: UEV enabled. An UEV is generated by one of the following events:

• – Counter overflow
• – Setting the UG bit

Buffered registers are then loaded with their preload values.

1: UEV disabled. No UEV is generated, shadow registers keep their value (ARR, PSC, CCRx). The counter and the prescaler are reinitialized if the UG bit is set.

Bit 0 CEN : Counter enable

0: Counter disabled

1: Counter enabled

CEN is cleared automatically in one-pulse mode, when an update event occurs.

17.5.2 TIM12 slave mode control register (TIMx_SMCR)

Address offset: 0x08

Reset value: 0x0000

Bits 15:8 Reserved, must be kept at reset value.

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 synchronization between the current timer and its slaves (through TRGO). It is useful in order to synchronize several timers on a single external event.

Bits 6:4 TS : Trigger selection

This bitfield selects the trigger input to be used to synchronize the counter.

000: Internal Trigger 0 (ITR0)

001: Internal Trigger 1 (ITR1)

010: Internal Trigger 2 (ITR2)

011: Internal Trigger 3 (ITR3)

100: TI1 Edge Detector (TI1F_ED)

101: Filtered Timer Input 1 (TI1FP1)

110: Filtered Timer Input 2 (TI2FP2)

111: Reserved.

See Table 53: TIMx Internal trigger connection on page 449 for more details on the meaning of ITRx for each timer.

Note: These bits must be changed only when they are not used (e.g. when SMS='000') to avoid wrong edge detections at the transition.

Bit 3 Reserved, must be kept at reset value.

Bits 2:0 SMS : Slave mode selection

When external signals are selected, the active edge of the trigger signal (TRGI) is linked to the polarity selected on the external input (see Input control register and Control register descriptions).

000: Slave mode disabled - if CEN = 1 then the prescaler is clocked directly by the internal clock

001: Reserved

010: Reserved

011: Reserved

100: Reset mode - Rising edge of the selected trigger input (TRGI) reinitializes the counter and generates an update of the registers

101: Gated mode - The counter clock is enabled when the trigger input (TRGI) is high. The counter stops (but is not reset) as soon as the trigger becomes low. Counter starts and stops are both controlled

110: Trigger mode - The counter starts on a rising edge of the trigger TRGI (but it is not reset). Only the start of the counter is controlled

111: External clock mode 1 - Rising edges of the selected trigger (TRGI) clock the counter

Note: The Gated mode must not be used if TI1F_ED is selected as the trigger input (TS='100'). Indeed, TI1F_ED outputs 1 pulse for each transition on TI1F, whereas the Gated mode checks the level of the trigger signal.

1. When a timer is not present in the product, the corresponding trigger ITRx is not available.

17.5.3 TIM12 Interrupt enable register (TIMx_DIER)

Address offset: 0x0C

Reset value: 0x0000

Bits 15:7 Reserved, must be kept at reset value.

Bit 6 TIE : Trigger interrupt enable

0: Trigger interrupt disabled.

1: Trigger interrupt enabled.

Bits 5:3 Reserved, must be kept at reset value.

Bit 2 CC2IE : Capture/Compare 2 interrupt enable

0: CC2 interrupt disabled.

1: CC2 interrupt enabled.

Bit 1 CC1IE : Capture/Compare 1 interrupt enable

0: CC1 interrupt disabled.

1: CC1 interrupt enabled.

Bit 0 UIE : Update interrupt enable

0: Update interrupt disabled.

1: Update interrupt enabled.

17.5.4 TIM12 status register (TIMx_SR)

Address offset: 0x10

Reset value: 0x0000

Bits 15:11 Reserved, must be kept at reset value.

Bit 10 CC2OF : Capture/compare 2 overcapture flag
refer to CC1OF description

Bit 9 CC1OF : Capture/Compare 1 overcapture flag

This flag is set by hardware only when the corresponding channel is configured in input capture mode. It is cleared by software by writing it to '0'.

0: No overcapture has been detected.

1: The counter value has been captured in TIMx_CCR1 register while CC1IF flag was already set

Bits 8:7 Reserved, must be kept at reset value.

Bit 6 TIF : Trigger interrupt flag

This flag is set by hardware on trigger event (active edge detected on TRGI input when the slave mode controller is enabled in all modes but gated mode. It is set when the counter starts or stops when gated mode is selected. It is cleared by software.

0: No trigger event occurred.

1: Trigger interrupt pending.

Bits 5:3 Reserved, must be kept at reset value.

Bit 2 CC2IF : Capture/Compare 2 interrupt flag
refer to CC1IF description

Bit 1 CC1IF : Capture/compare 1 interrupt flag

If channel CC1 is configured as output:

This flag is set by hardware when the counter matches the compare value. It is cleared by software.

0: No match.

1: The content of the counter TIMx_CNT matches the content of the TIMx_CCR1 register. When the contents of TIMx_CCR1 are greater than the contents of TIMx_ARR, the CC1IF bit goes high on the counter overflow.

If channel CC1 is configured as input:

This bit is set by hardware on a capture. It is cleared by software or by reading the TIMx_CCR1 register.

0: No input capture occurred.

1: The counter value has been captured in TIMx_CCR1 register (an edge has been detected on IC1 which matches the selected polarity).

Bit 0 UIF : Update interrupt flag

This bit is set by hardware on an update event. It is cleared by software.

0: No update occurred.

1: Update interrupt pending. This bit is set by hardware when the registers are updated:

• – At overflow and if UDIS='0' in the TIMx_CR1 register.
• – When CNT is reinitialized by software using the UG bit in TIMx_EGR register, if URS='0' and UDIS='0' in the TIMx_CR1 register.
• – When CNT is reinitialized by a trigger event (refer to the synchro control register description), if URS='0' and UDIS='0' in the TIMx_CR1 register.

17.5.5 TIM12 event generation register (TIMx_EGR)

Address offset: 0x14

Reset value: 0x0000

Bits 15:7 Reserved, must be kept at reset value.

Bit 6 TG : Trigger generation

This bit is set by software in order to generate an event, it is automatically cleared by hardware.

0: No action

1: The TIF flag is set in the TIMx_SR register. Related interrupt can occur if enabled

Bits 5:3 Reserved, must be kept at reset value.

Bit 2 CC2G : Capture/compare 2 generation

refer to CC1G description

Bit 1 CC1G : Capture/compare 1 generation

This bit is set by software to generate an event, it is automatically cleared by hardware.

0: No action

1: A capture/compare event is generated on channel 1:

If channel CC1 is configured as output:

the CC1IF flag is set, the corresponding interrupt is sent if enabled.

If channel CC1 is configured as input:

The current counter value is captured in the TIMx_CCR1 register. The CC1IF flag is set, the corresponding interrupt is sent if enabled. The CC1OF flag is set if the CC1IF flag was already high.

Bit 0 UG : Update generation

This bit can be set by software, it is automatically cleared by hardware.

0: No action

1: Re-initializes the counter and generates an update of the registers. The prescaler counter is also cleared and the prescaler ratio is not affected. The counter is cleared.

17.5.6 TIM12 capture/compare mode register 1 (TIMx_CCMR1)

Address offset: 0x18

Reset value: 0x0000

The channels can be used in input (capture mode) or in output (compare mode). The direction of a channel is defined by configuring the corresponding CCxS bits. All the other bits in this register have different functions in input and output modes. For a given bit, OCxx describes its function when the channel is configured in output mode, ICxx describes its function when the channel is configured in input mode. So one must take care that the same bit can have different meanings for the input stage and the output stage.

Output compare mode

Bit 15 Reserved, must be kept at reset value.

Bits 14:12 OC2M[2:0] : Output compare 2 mode

Bit 11 OC2PE : Output compare 2 preload enable

Bit 10 OC2FE : Output compare 2 fast enable

Bits 9:8 CC2S[1:0] : Capture/Compare 2 selection

This bitfield 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 works only if an internal trigger input is selected through the TS bit (TIMx_SMCR register)

Note: The CC2S bits are writable only when the channel is OFF (CC2E = 0 in TIMx_CCER).

Bit 7 Reserved, must be kept at reset value.

These bits define the behavior of the output reference signal OC1REF from which OC1 and OC1N are derived. OC1REF is active high whereas the active levels of OC1 and OC1N depend on the CC1P and CC1NP bits, respectively.

000: Frozen - The comparison between the output compare register TIMx_CCR1 and the counter TIMx_CNT has no effect on the outputs. (this mode is used to generate a timing base).

001: Set channel 1 to active level on match. The OC1REF signal is forced high when the TIMx_CNT counter matches the capture/compare register 1 (TIMx_CCR1).

010: Set channel 1 to inactive level on match. The OC1REF signal is forced low when the TIMx_CNT counter matches the capture/compare register 1 (TIMx_CCR1).

011: Toggle - OC1REF toggles when TIMx_CNT=TIMx_CCR1

100: Force inactive level - OC1REF is forced low

101: Force active level - OC1REF is forced high

110: PWM mode 1 - In upcounting, channel 1 is active as long as TIMx_CNT<TIMx_CCR1 else it is inactive. In downcounting, channel 1 is inactive (OC1REF='0') as long as TIMx_CNT>TIMx_CCR1, else it is active (OC1REF='1')

111: PWM mode 2 - In upcounting, channel 1 is inactive as long as TIMx_CNT<TIMx_CCR1 else it is active. In downcounting, channel 1 is active as long as TIMx_CNT>TIMx_CCR1 else it is inactive.

Note: In PWM mode 1 or 2, the OCREF level changes only when the result of the comparison changes or when the output compare mode switches from “frozen” mode to “PWM” mode.

0: Preload register on TIMx_CCR1 disabled. TIMx_CCR1 can be written at anytime, the new value is taken into account immediately

1: Preload register on TIMx_CCR1 enabled. Read/Write operations access the preload register. TIMx_CCR1 preload value is loaded into the active register at each update event

Note: The PWM mode can be used without validating the preload register only in one-pulse mode (OPM bit set in the TIMx_CR1 register). Else the behavior is not guaranteed.

This bit is used to accelerate the effect of an event on the trigger in input on the CC output.

0: CC1 behaves normally depending on the counter and CCR1 values even when the trigger is ON. The minimum delay to activate the CC1 output when an edge occurs on the trigger input is 5 clock cycles

1: An active edge on the trigger input acts like a compare match on the CC1 output. Then, OC is set to the compare level independently of the result of the comparison. Delay to sample the trigger input and to activate CC1 output is reduced to 3 clock cycles. OC1FE acts only if the channel is configured in PWM1 or PWM2 mode.

This bitfield 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 works only if an internal trigger input is selected through the TS bit (TIMx_SMCR register)

Note: The CC1S bits are writable only when the channel is OFF (CC1E = 0 in TIMx_CCER).

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 bitfield 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 works only if an internal trigger input is selected through the TS bit (TIMx_SMCR register)

Note: The CC2S bits are writable only when the channel is OFF (CC2E = 0 in TIMx_CCER).

Bits 7:4 IC1F : Input capture 1 filter

This bitfield defines the frequency used to sample the TI1 input and the length of the digital filter applied to TI1. The digital filter is made of an event counter in which N events are needed to validate a transition on the output:

Note: In the current silicon revision, \( f_{DTS} \) is replaced in the formula by CK_INT when ICxF[3:0]= 1, 2 or 3.

Bits 3:2 IC1PSC : Input capture 1 prescaler

This bitfield defines the ratio of the prescaler acting on the 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 bitfield 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: The CC1S bits are writable only when the channel is OFF (CC1E = 0 in TIMx_CCER).

17.5.7 TIM12 capture/compare enable register (TIMx_CCER)

Address offset: 0x20

Reset value: 0x0000

Bits 15:8 Reserved, must be kept at reset value.

Bit 7 CC2NP : Capture/Compare 2 output Polarity
refer to CC1NP description

Bit 6 Reserved, must be kept at reset value.

Bit 5 CC2P : Capture/Compare 2 output Polarity
refer to CC1P description

Bit 4 CC2E : Capture/Compare 2 output enable
refer to CC1E description

Bit 3 CC1NP : Capture/Compare 1 complementary output Polarity
CC1 channel configured as output: CC1NP must be kept cleared
CC1 channel configured as input: CC1NP is used in conjunction with CC1P to define TI1FP1/TI2FP1 polarity (refer to CC1P description).

Bit 2 Reserved, must be kept at reset value.

Bit 1 CC1P : Capture/Compare 1 output Polarity.

CC1 channel configured as output:

0: OC1 active high.

1: OC1 active low.

CC1 channel configured as input:

CC1NP/CC1P bits select TI1FP1 and TI2FP1 polarity for trigger or capture operations.

00: noninverted/rising edge

Circuit is sensitive to TIxFP1 rising edge (capture, trigger in reset, external clock or trigger mode), TIxFP1 is not inverted (trigger in gated mode, encoder mode).

01: inverted/falling edge

Circuit is sensitive to TIxFP1 falling edge (capture, trigger in reset, external clock or trigger mode), TIxFP1 is inverted (trigger in gated mode, encoder mode).

10: reserved, do not use this configuration.

Note: 11: noninverted/both edges

Circuit is sensitive to both TIxFP1 rising and falling edges (capture, trigger in reset, external clock or trigger mode), TIxFP1 is not inverted (trigger in gated mode). This configuration must not be used for encoder mode.

Bit 0 CC1E : Capture/Compare 1 output enable.

CC1 channel configured as output:

0: Off - OC1 is not active.

1: On - OC1 signal is output on the corresponding output pin.

CC1 channel configured as input:

This bit determines if a capture of the counter value can actually be done into the input capture/compare register 1 (TIMx_CCR1) or not.

0: Capture disabled.

1: Capture enabled.

Table 49. Output control bit for standard OCx channels

Note: The states of the external I/O pins connected to the standard OCx channels depend on the state of the OCx channel and on the GPIO registers.

17.5.8 TIM12 counter (TIMx_CNT)

Address offset: 0x24

Reset value: 0x0000 0000

Bits 15:0 CNT[15:0] : Counter value

17.5.9 TIM12 prescaler (TIMx_PSC)

Address offset: 0x28

Reset value: 0x0000

Bits 15:0 PSC[15:0] : Prescaler value

The counter clock frequency CK_CNT is equal to \( f_{CK\_PSC} / (PSC[15:0] + 1) \) .

PSC contains the value to be loaded into the active prescaler register at each update event.

17.5.10 TIM12 auto-reload register (TIMx_ARR)

Address offset: 0x2C

Reset value: 0x0000 0000

Bits 15:0 ARR[15:0] : Auto-reload value

ARR is the value to be loaded into the actual auto-reload register.

Refer to the Section 17.4.1: Time-base unit on page 370 for more details about ARR update and behavior.

The counter is blocked while the auto-reload value is null.

17.5.11 TIM12 capture/compare register 1 (TIMx_CCR1)

Address offset: 0x34

Reset value: 0x0000

CCR1 is the value to be loaded into the actual capture/compare 1 register (preload value). It is loaded permanently if the preload feature is not selected in the TIMx_CCMR1 register (OC1PE bit). Else the preload value is copied into the active capture/compare 1 register when an update event occurs.

The active capture/compare register contains the value to be compared to the TIMx_CNT counter and signaled on the OC1 output.

CCR1 is the counter value transferred by the last input capture 1 event (IC1).

17.5.12 TIM12 capture/compare register 2 (TIMx_CCR2)

Address offset: 0x38

Reset value: 0x0000

CCR2 is the value to be loaded into the actual capture/compare 2 register (preload value). It is loaded permanently if the preload feature is not selected in the TIMx_CCMR2 register (OC2PE bit). Else the preload value is copied into the active capture/compare 2 register when an update event occurs.

The active capture/compare register contains the value to be compared to the TIMx_CNT counter and signalled on the OC2 output.

CCR2 is the counter value transferred by the last input capture 2 event (IC2).

17.5.13 TIM12 register map

TIM12 registers are mapped as 16-bit addressable registers as described below:

Table 50. TIM12 register map and reset values

Table 50. TIM12 register map and reset values (continued)

Table 50. TIM12 register map and reset values (continued)

Refer to Section 2.2 on page 40 for the register boundary addresses.

17.6 TIM13/14 registers

The peripheral registers have to be written by half-words (16 bits) or words (32 bits). Read accesses can be done by bytes (8 bits), half-words (16 bits) or words (32 bits).

17.6.1 TIM13/14 control register 1 (TIMx_CR1)

Address offset: 0x00

Reset value: 0x0000

Bits 15:10 Reserved, must be kept at reset value.

Bits 9:8 CKD : Clock division

This bit-field indicates the division ratio between the timer clock (CK_INT) frequency and sampling clock used by the digital filters (ETR, TIx),

00: \( t_{DTS} = t_{CK\_INT} \)
01: \( t_{DTS} = 2 \times t_{CK\_INT} \)
10: \( t_{DTS} = 4 \times t_{CK\_INT} \)
11: Reserved

Bit 7 ARPE : Auto-reload preload enable

0: TIMx_ARR register is not buffered
1: TIMx_ARR register is buffered

Bits 6:3 Reserved, must be kept at reset value.

Bit 2 URS : Update request source

This bit is set and cleared by software to select the update interrupt (UEV) sources.

0: Any of the following events generate an UEV if enabled:

• – Counter overflow
• – Setting the UG bit

1: Only counter overflow generates an UEV if enabled.

Bit 1 UDIS : Update disable

This bit is set and cleared by software to enable/disable update interrupt (UEV) event generation.

0: UEV enabled. An UEV is generated by one of the following events:

• – Counter overflow
• – Setting the UG bit.

Buffered registers are then loaded with their preload values.

1: UEV disabled. No UEV is generated, shadow registers keep their value (ARR, PSC, CCRx). The counter and the prescaler are reinitialized if the UG bit is set.

Bit 0 CEN : Counter enable

0: Counter disabled
1: Counter enabled

17.6.2 TIM13/14 Interrupt enable register (TIMx_DIER)

Address offset: 0x0C

Reset value: 0x0000

Bits 15:2 Reserved, must be kept at reset value.

Bit 1 CC1IE : Capture/Compare 1 interrupt enable

0: CC1 interrupt disabled

1: CC1 interrupt enabled

Bit 0 UIE : Update interrupt enable

0: Update interrupt disabled

1: Update interrupt enabled

17.6.3 TIM13/14 status register (TIMx_SR)

Address offset: 0x10

Reset value: 0x0000

Bits 15:10 Reserved, must be kept at reset value.

Bit 9 CC1OF : Capture/Compare 1 overcapture flag

This flag is set by hardware only when the corresponding channel is configured in input capture mode. It is cleared by software by writing it to '0'.

0: No overcapture has been detected.

1: The counter value has been captured in TIMx_CCR1 register while CC1IF flag was already set

Bits 8:2 Reserved, must be kept at reset value.

Bit 1 CC1IF : Capture/compare 1 interrupt flag

If channel CC1 is configured as output:

This flag is set by hardware when the counter matches the compare value. It is cleared by software.

0: No match.

1: The content of the counter TIMx_CNT matches the content of the TIMx_CCR1 register. When the contents of TIMx_CCR1 are greater than the contents of TIMx_ARR, the CC1IF bit goes high on the counter overflow.

If channel CC1 is configured as input:

This bit is set by hardware on a capture. It is cleared by software or by reading the TIMx_CCR1 register.

0: No input capture occurred.

1: The counter value has been captured in TIMx_CCR1 register (an edge has been detected on IC1 which matches the selected polarity).

Bit 0 UIF : Update interrupt flag

This bit is set by hardware on an update event. It is cleared by software.

0: No update occurred.

1: Update interrupt pending. This bit is set by hardware when the registers are updated:

• – At overflow and if UDIS='0' in the TIMx_CR1 register.
• – When CNT is reinitialized by software using the UG bit in TIMx_EGR register, if URS='0' and UDIS='0' in the TIMx_CR1 register.

17.6.4 TIM13/14 event generation register (TIMx_EGR)

Address offset: 0x14

Reset value: 0x0000

Bits 15:2 Reserved, must be kept at reset value.

Bit 1 CC1G : Capture/compare 1 generation

This bit is set by software in order to generate an event, it is automatically cleared by hardware.

0: No action

1: A capture/compare event is generated on channel 1:

If channel CC1 is configured as output:

CC1IF flag is set, Corresponding interrupt or is sent if enabled.

If channel CC1 is configured as input:

The current value of the counter is captured in TIMx_CCR1 register. The CC1IF flag is set, the corresponding interrupt is sent if enabled. The CC1OF flag is set if the CC1IF flag was already high.

Bit 0 UG : Update generation

This bit can be set by software, it is automatically cleared by hardware.

0: No action

1: Re-initialize the counter and generates an update of the registers. Note that the prescaler counter is cleared too (anyway the prescaler ratio is not affected). The counter is cleared.

17.6.5 TIM13/14 capture/compare mode register 1 (TIMx_CCMR1)

Address offset: 0x18

Reset value: 0x0000

The channels can be used in input (capture mode) or in output (compare mode). The direction of a channel is defined by configuring the corresponding CCxS bits. All the other bits of this register have a different function in input and in output mode. For a given bit, OCxx describes its function when the channel is configured in output, ICxx describes its function when the channel is configured in input. So one must take care that the same bit can have a different meaning for the input stage and for the output stage.

Output compare mode

Bits 15:7 Reserved, must be kept at reset value.

Bits 6:4 OC1M : Output compare 1 mode

These bits define the behavior of the output reference signal OC1REF from which OC1 is derived. OC1REF is active high whereas OC1 active level depends on CC1P bit.

000: Frozen. The comparison between the output compare register TIMx_CCR1 and the counter TIMx_CNT has no effect on the outputs.

001: Set channel 1 to active level on match. OC1REF signal is forced high when the counter TIMx_CNT matches the capture/compare register 1 (TIMx_CCR1).

010: Set channel 1 to inactive level on match. OC1REF signal is forced low when the counter TIMx_CNT matches the capture/compare register 1 (TIMx_CCR1).

011: Toggle - OC1REF toggles when TIMx_CNT = TIMx_CCR1.

100: Force inactive level - OC1REF is forced low.

101: Force active level - OC1REF is forced high.

110: PWM mode 1 - Channel 1 is active as long as TIMx_CNT < TIMx_CCR1 else inactive.

111: PWM mode 2 - Channel 1 is inactive as long as TIMx_CNT < TIMx_CCR1 else active.

Note: In PWM mode 1 or 2, the OCREF level changes when the result of the comparison changes or when the output compare mode switches from frozen to PWM mode.

Bit 3 OC1PE : Output compare 1 preload enable

0: Preload register on TIMx_CCR1 disabled. TIMx_CCR1 can be written at anytime, the new value is taken in account immediately.

1: Preload register on TIMx_CCR1 enabled. Read/Write operations access the preload register. TIMx_CCR1 preload value is loaded in the active register at each update event.

Note: The PWM mode can be used without validating the preload register only in one pulse mode (OPM bit set in TIMx_CR1 register). Else the behavior is not guaranteed.

Bit 2 OC1FE : Output compare 1 fast enable

This bit is used to accelerate the effect of an event on the trigger in input on the CC output.

0: CC1 behaves normally depending on counter and CCR1 values even when the trigger is ON. The minimum delay to activate CC1 output when an edge occurs on the trigger input is 5 clock cycles.

1: An active edge on the trigger input acts like a compare match on CC1 output. OC is then set to the compare level independently of the result of the comparison. Delay to sample the trigger input and to activate CC1 output is reduced to 3 clock cycles. OC1FE acts only if the channel is configured in PWM1 or PWM2 mode.

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: Reserved

11: Reserved

Note: CC1S bits are writable only when the channel is OFF (CC1E = 0 in TIMx_CCER).

Input capture mode

Bits 15:8 Reserved, must be kept at reset value.

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 events are needed to validate a transition on the output:

0000: No filter, sampling is done at \( f_{DTS} \) 1000: \( f_{SAMPLING}=f_{DTS}/8 \) , N=6
0001: \( f_{SAMPLING}=f_{CK\_INT} \) , N=2 1001: \( f_{SAMPLING}=f_{DTS}/8 \) , N=8
0010: \( f_{SAMPLING}=f_{CK\_INT} \) , N=4 1010: \( f_{SAMPLING}=f_{DTS}/16 \) , N=5
0011: \( f_{SAMPLING}=f_{CK\_INT} \) , N=8 1011: \( f_{SAMPLING}=f_{DTS}/16 \) , N=6
0100: \( f_{SAMPLING}=f_{DTS}/2 \) , N=6 1100: \( f_{SAMPLING}=f_{DTS}/16 \) , N=8
0101: \( f_{SAMPLING}=f_{DTS}/2 \) , N=8 1101: \( f_{SAMPLING}=f_{DTS}/32 \) , N=5
0110: \( f_{SAMPLING}=f_{DTS}/4 \) , N=6 1110: \( f_{SAMPLING}=f_{DTS}/32 \) , N=6
0111: \( f_{SAMPLING}=f_{DTS}/4 \) , N=8 1111: \( f_{SAMPLING}=f_{DTS}/32 \) , N=8

Note: In current silicon revision, \( f_{DTS} \) is replaced in the formula by CK_INT when ICxF[3:0]= 1, 2 or 3.

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

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).

17.6.6 TIM13/14 capture/compare enable register (TIMx_CCER)

Address offset: 0x20

Reset value: 0x0000

Bits 15:4 Reserved, must be kept at reset value.

Bit 3 CC1NP : Capture/Compare 1 complementary output Polarity.

CC1 channel configured as output: CC1NP must be kept cleared.

CC1 channel configured as input: CC1NP bit is used in conjunction with CC1P to define TI1FP1 polarity (refer to CC1P description).

Bit 2 Reserved, must be kept at reset value.

Bit 1 CC1P : Capture/Compare 1 output Polarity.

CC1 channel configured as output:

0: OC1 active high

1: OC1 active low

CC1 channel configured as input:

The CC1P bit selects TI1FP1 and TI2FP1 polarity for trigger or capture operations.

00: noninverted/rising edge

Circuit is sensitive to TI1FP1 rising edge (capture mode), TI1FP1 is not inverted.

01: inverted/falling edge

Circuit is sensitive to TI1FP1 falling edge (capture mode), TI1FP1 is inverted.

10: reserved, do not use this configuration.

11: noninverted/both edges

Circuit is sensitive to both TI1FP1 rising and falling edges (capture mode), TI1FP1 is not inverted.

Bit 0 CC1E : Capture/Compare 1 output enable.

CC1 channel configured as output:

0: Off - OC1 is not active

1: On - OC1 signal is output on the corresponding output pin

CC1 channel configured as input:

This bit determines if a capture of the counter value can actually be done into the input capture/compare register 1 (TIMx_CCR1) or not.

0: Capture disabled

1: Capture enabled

Table 51. Output control bit for standard OCx channels

Note: The state of the external I/O pins connected to the standard OCx channels depends on the OCx channel state and the GPIO registers.

17.6.7 TIM13/14 counter (TIMx_CNT)

Address offset: 0x24

Reset value: 0x0000

Bits 15:0 CNT[15:0] : Counter value

17.6.8 TIM13/14 prescaler (TIMx_PSC)

Address offset: 0x28

Reset value: 0x0000

Bits 15:0 PSC[15:0] : Prescaler value

The counter clock frequency \( CK\_CNT \) is equal to \( f_{CK\_PSC} / (PSC[15:0] + 1) \) .

PSC contains the value to be loaded in the active prescaler register at each update event.

17.6.9 TIM13/14 auto-reload register (TIMx_ARR)

Address offset: 0x2C

Reset value: 0x0000

Bits 15:0 ARR[15:0] : Auto-reload value

ARR is the value to be loaded in the actual auto-reload register.

Refer to Section 17.4.1: Time-base unit on page 370 for more details about ARR update and behavior.

The counter is blocked while the auto-reload value is null.

17.6.10 TIM13/14 capture/compare register 1 (TIMx_CCR1)

Address offset: 0x34

Reset value: 0x0000

Bits 15:0 CCR1[15:0] : Capture/Compare 1 value

If channel CC1 is configured as output:

CCR1 is the value to be loaded in the actual capture/compare 1 register (preload value).

It is loaded permanently if the preload feature is not selected in the TIMx_CCMR1 register (bit OC1PE). Else the preload value is copied in the active capture/compare 1 register when an update event occurs.

The active capture/compare register contains the value to be compared to the counter TIMx_CNT and signaled on OC1 output.

If channel CC1 is configured as input:

CCR1 is the counter value transferred by the last input capture 1 event (IC1).

17.6.11 TIM14 option register (TIM14_OR)

Address offset: 0x50

Reset value: 0x0000

Bits 15:2 Reserved, must be kept at reset value.

Bits 1:0 TI1_RMP[1:0] : Timer Input 1 remap

Set and cleared by software.

00: TIM14 Channel1 is connected to the GPIO. Refer to the Alternate function mapping table in the device datasheets.

01: the RTC_CLK is connected to the TIM14_CH1 input for calibration purposes

10: TIM14_CH1 input is connected to HSE/32 clock

11: TIM14_CH1 input is connected to MCO clock.

17.6.12 TIM13/14 register map

TIMx registers are mapped as 16-bit addressable registers as described in the tables below:

Table 52. TIM13/14 register map and reset values