 Hello, and welcome to this presentation of the STM32L5 low-power timer or LP-TIM. It covers the features of this peripheral, which offers a set of timing features and can generate waveforms even in low-power modes. The low-power timer peripheral embedded in the STM32L5 microcontroller provides a 16-bit timer that is able to run even in low-power modes. This is made possible thanks to a flexible clocking scheme. The low-power timer peripheral provides basic general-purpose timer functions. One major function of the low-power timer is its capability to keep running even when no internal clock source is active when configured in asynchronous counting mode. The low-power timer's main feature is its ability to keep running even in low-power mode when almost all clock sources are turned off. The low-power timer has a very flexible clocking scheme. It can be clocked from on-ship clock sources, LSE, LSI, HSI-16, or APB clocks. Or it can be clocked from an external clock source over the low-power timer's LP-TIM in one input. This latter feature is used for building pulse counter applications and is a key function for metering applications like gas meters, etc. The low-power timer features up to eight external trigger sources with configurable polarity. External trigger inputs feature digital filters to cancel out faulty triggers that could be raised in noisy operating environments. The low-power timer can be configured to run either in continuous or one-shot mode. One-shot mode is used for generating pulse waveforms while continuous mode is used to generate PWM waveforms. The low-power timer is a peripheral with two clock domains. The APB clock domain contains the peripheral's APB interface. The kernel clock domain contains the low-power timer peripheral's core functions. The kernel clock domain can be clocked by internal clock sources or by an external clock source through the timer's LP-TIM in one input. The low-power timer peripheral embeds a 16-bit counter that is fed through a power of two pre-scaler. The low-power timer peripheral features a 16-bit auto-reload register and a 16-bit compare register that are used to set the period and duty cycle respectively for a PWM waveform signal output on the timer's LP-TIM out output. The low-power timer features a repetition counter which allows adjustment of the counter rollover. The low-power timer features an encoder mode function that can be used to interface with incremental quadrature encoder sensors using the peripheral's LP-TIM in one MUX and LP-TIM in two MUX inputs. Both inputs feature glitch filtering circuitry. The LP-TIM-CMP and LP-TIM-ARR registers in conjunction with the bitfield's wave from the LP-TIM-CFGR register and SNG-STRT from the LP-TIM-CR register are used to control the output waveform. The output waveform is either a typical PWM signal with its period and duty cycle controlled by the LP-TIM-ARR and LP-TIM-CMP registers respectively or it is a single pulse with the last output state defined by the configured waveform. If the last output state is the same as the one at the waveform's beginning, then one pulse mode is configured. If not, then set once mode is configured. The low power timer's output polarity is controlled through the WAV-POL bitfield in the LP-TIM-CFGR register. The low power timer features a counter reset function used to reset to zero the contents of the LP-TIM-CNT register. Two counter reset mechanisms are possible, the synchronous counter reset mechanism and the asynchronous counter reset mechanism. A synchronous counter reset is performed by setting the count RST bit. Due to the synchronous nature of this reset, it only takes place after a synchronization delay of three LP-TIM kernel clock cycles. When the RST-ARE bit is set, an asynchronous counter reset is performed on the next APB read access to the LP-TIM-CNT register. The low power timer features an encoder mode function that can interface with the incremental quadrature encoder sensors using the peripheral's input 1 and input 2 inputs. Both inputs feature glitch filtering circuitry. The encoder function is similar to the one embedded in the general purpose timers. In order to use the encoder mode function, the low power timer must be running in continuous mode. One important thing to note is that only low power timers 1 and 2 embed the encoder mode function. The low power timer peripheral features 9 interrupt sources. The compare match interrupt is raised once the content of the counter register LP-TIM-CNT matches or is greater than the compare register LP-TIM-CMP content. The auto reload match interrupt is raised when the counter register's content matches the auto reload register's content. The external trigger event interrupt is raised when a valid external trigger is detected. The auto reload register write completed, the compare register write completed, and the repetition register write completed interrupts are raised when the transfer of the content of the LP-TIM-ARR register, the LP-TIM-CMP register, and the LP-TIM-RCR register respectively is completed from the peripheral's APB interface logic into the peripheral's core logic which are contained by two different clock domains. These three interrupts are useful in mitigating the overhead of polling on the status of writing to these two registers when the peripheral core clock is too slow compared to the APB interface clock. The up and down direction change interrupts are raised when the encoder mode function is enabled and the counting direction is changed from up to down or vice versa. The counting direction of the low power timer's counter reflects the rotation direction of the quadrature's sensor. The update event is raised when the repetition counter underflows and the LP-TIM counter overflows. The low power timer peripheral is active in run, sleep, and stop power modes. The low power timer is able to wake up the microcontroller from either sleep or stop modes. The STM32L5 devices embed three LP-TIM peripherals where only LP-TIM1 instance embeds the encoder mode. Wake up from stop 0 and stop 1 modes is supported by all of LP-TIM instances while wake up from stop 2 is only supported by LP-TIM1 and LP-TIM3. For more details, please refer to the following documentation available on our website.