Maxim Integrated MAX32660, User Manual

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MAX32660 User Guide
Maxim Integrated Page 105 of 195
10 Timers
The MAX32660 contains three 32-bit, reloadable timers. Each timer provides multiple operating modes. Timer modes
supported include:
•
One-Shot: Timer counts up to terminal value then halts.
•
Continuous: Timer counts up to terminal value then repeats.
•
Counter: Timer counts input edges received on timer input pin (Timer 0 only).
•
Capture: Captures a snapshot of the current timer count when timer input edge transitions (Timer 0 only).
•
Compare: Timer pin toggles when timer exceeds terminal count (Timer 0 only).
•
Gated: Timer increments only when timer input pin is asserted (Timer 0).
•
Capture/Compare: Timer counts when timer input is asserted, captures timer count when input is deasserted
(Timer 0 only).
10.1 Features
•
32-bit reload counter
•
Programmable prescaler with values from 1 to 4096
•
Independent interrupt
•
Timer 0 supports a Timer I/O alternate function pin for:
− Capture, compare, and capture/compare capability
− Timer pin available as alternate function
− Configurable Input pin for event triggering, clock gating, or capture signal
− Configurable output pin for event output and PWM signal generation
10.2 Basic Operation
The timer modes operate by incrementing the TMRn_CNT register, driven by either the timer clock, an external stimulus on
the timer pin, or a combination of both. The TMRn_CNT register is always readable, even while the timer is enabled and
counting.
Each timer mode has a user-configurable timer period, which terminates on the timer clock cycle following the end of timer
period condition. Each timer mode has a different response at the end of a timer period, which can include changing the
state of the timer pin, capturing a timer value, reloading
TMRn_CNT with a new starting value, or disabling the counter. The
end of a timer period will always set the corresponding interrupt bit and can generate an interrupt, if enabled.
In most modes the timer peripheral automatically sets TMRn_CNT to 0x0000 0001 at the end of a timer period, but
TMRn_CNT is set to 0x0000 0000 following a system reset. This means the first timer period following a system reset will be
one timer clock longer than subsequent timer periods if TMRn_CNT is not initialized to 0x0000 0001 during the timer
configuration step.
Clocking of timer functions is driven by the timer clock frequency, f
CNT_CLK
. The timer clock frequency is a user-configurable,
division of the system peripheral clock, PCLK. Each timer has an independent prescaler, allowing timers to operate at
different frequencies. The prescaler can be set from 1 to 4096 using the
TMRn_CN .pres3 : TMRn_CN .pres fields. Unless
otherwise mentioned, the timer clock is generated as follows: