Datasheet
DS10668 Rev 6 29/126
STM32L031x4/6 Functional overview
33
3.15 Timers and watchdogs
The ultra-low-power STM32L031x4/6 devices include three general-purpose timers, one
low- power timer (LPTM), two watchdog timers and the SysTick timer.
Table 9 compares the features of the general-purpose and basic timers.
3.15.1 General-purpose timers (TIM2, TIM21 and TIM22)
There are three synchronizable general-purpose timers embedded in the STM32L031x4/6
devices (see Table 9 for differences).
TIM2
TIM2 is based on 16-bit auto-reload up/down counter. It includes a 16-bit prescaler. It
features four independent channels each for input capture/output compare, PWM or one-
pulse mode output.
The TIM2 general-purpose timers can work together or with the TIM21 and TIM22 general-
purpose timers via the Timer Link feature for synchronization or event chaining. Their
counter can be frozen in debug mode. Any of the general-purpose timers can be used to
generate PWM outputs.
TIM2 has independent DMA request generation.
This timer is capable of handling quadrature (incremental) encoder signals and the digital
outputs from 1 to 3 hall-effect sensors.
TIM21 and TIM22
TIM21 and TIM22 are based on a 16-bit auto-reload up/down counter. They include a 16-bit
prescaler. They have two independent channels for input capture/output compare, PWM or
one-pulse mode output. They can work together and be synchronized with the TIM2, full-
featured general-purpose timers.
They can also be used as simple time bases and be clocked by the LSE clock source
(32.768 kHz) to provide time bases independent from the main CPU clock.
Table 9. Timer feature comparison
Timer
Counter
resolution
Counter type Prescaler factor
DMA
request
generation
Capture/compare
channels
Complementary
outputs
TIM2 16-bit
Up, down,
up/down
Any integer between
1 and 65536
Yes 4 No
TIM21,
TIM22
16-bit
Up, down,
up/down
Any integer between
1 and 65536
No 2 No
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