Datasheet

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STM32F21xxx Functional overview
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3.20.2 General-purpose timers (TIMx)
There are ten synchronizable general-purpose timers embedded in the STM32F21x devices
(see Table 4 for differences).
TIM2, TIM3, TIM4, TIM5
The STM32F21x include 4 full-featured general-purpose timers. TIM2 and TIM5 are 32-bit
timers, and TIM3 and TIM4 are 16-bit timers. The TIM2 and TIM5 timers are based on a 32-
bit auto-reload up/downcounter and a 16-bit prescaler. The TIM3 and TIM4 timers are based
on a 16-bit auto-reload up/downcounter and a 16-bit prescaler. They all feature 4
independent channels for input capture/output compare, PWM or one-pulse mode output.
This gives up to 16 input capture/output compare/PWMs on the largest packages.
The TIM2, TIM3, TIM4, TIM5 general-purpose timers can work together, or with the other
general-purpose timers and the advanced-control timers TIM1 and TIM8 via the Timer Link
feature for synchronization or event chaining.
The counters of TIM2, TIM3, TIM4, TIM5 can be frozen in debug mode. Any of these
general-purpose timers can be used to generate PWM outputs.
TIM2, TIM3, TIM4, TIM5 all have independent DMA request generation. They are capable
of handling quadrature (incremental) encoder signals and the digital outputs from 1 to 4 hall-
effect sensors.
TIM10, TIM11 and TIM9
These timers are based on a 16-bit auto-reload upcounter and a 16-bit prescaler. TIM10 and
TIM11 feature one independent channel, whereas TIM9 has two independent channels for
input capture/output compare, PWM or one-pulse mode output. They can be synchronized
with the TIM2, TIM3, TIM4, TIM5 full-featured general-purpose timers. They can also be
used as simple time bases.
TIM12, TIM13 and TIM14
These timers are based on a 16-bit auto-reload upcounter and a 16-bit prescaler. TIM13 and
TIM14 feature one independent channel, whereas TIM12 has two independent channels for
input capture/output compare, PWM or one-pulse mode output. They can be synchronized
with the TIM2, TIM3, TIM4, TIM5 full-featured general-purpose timers.
They can also be used as simple time bases.
3.20.3 Basic timers TIM6 and TIM7
These timers are mainly used for DAC trigger and waveform generation. They can also be
used as a generic 16-bit time base.
3.20.4 Independent watchdog
The independent watchdog is based on a 12-bit downcounter and 8-bit prescaler. It is
clocked from an independent 32 kHz internal RC and as it operates independently from the
main clock, it can operate in Stop and Standby modes. It can be used either as a watchdog
to reset the device when a problem occurs, or as a free-running timer for application timeout