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General-purpose timers (TIM2/TIM3/TIM4)
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21 General-purpose
timers
(TIM2/TIM3/TIM4)
21.1 TIM2/TIM3/TIM4
introduction
The general-purpose timers consist of a 16-bit or 32-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 and 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 timers are completely independent, and do not share any resources. They can be
synchronized together as described in
Section 21.3.19: Timer synchronization
Note:
TIM3 and TIM4 are available only on STM32F302xB/C/D/E devices.
21.2
TIM2/TIM3/TIM4 main features
General-purpose TIMx timer features include:
•
16-bit (TIM3 and TIM4) or 32-bit (TIM2) up, down, up/down auto-reload counter.
•
16-bit programmable prescaler used to divide (also “on the fly”) the counter clock
frequency by any factor between 1 and 65535.
•
Up to 4 independent channels for:
–
Input capture
–
Output compare
–
PWM generation (Edge- and Center-aligned modes)
–
One-pulse mode output
•
Synchronization circuit to control the timer with external signals and to interconnect
several timers.
•
Interrupt/DMA generation on the following events:
–
Update: counter overflow/underflow, counter initialization (by software or
internal/external trigger)
–
Trigger event (counter start, stop, initialization or count by internal/external trigger)
–
Input capture
–
Output compare
•
Supports incremental (quadrature) encoder and hall-sensor circuitry for positioning
purposes
•
Trigger input for external clock or cycle-by-cycle current management