LM3S9B81 Datasheet, PDF (423/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Stellaris® LM3S9B81 Microcontroller
11 General-Purpose Timers
Programmable timers can be used to count or time external events that drive the Timer input pins.
The Stellaris^® General-Purpose Timer Module (GPTM) contains four GPTM blocks (Timer 0, Timer
1, Timer 2, and Timer 3). Each GPTM block provides two 16-bit timers/counters (referred to as
Timer A and Timer B) that can be configured to operate independently as timers or event counters,
or configured to operate as one 32-bit timer or one 32-bit Real-Time Clock (RTC). Timers can also
be used to trigger μDMA transfers.
In addition, timers can be used to trigger analog-to-digital conversions (ADC). The ADC trigger
signals from all of the general-purpose timers are ORed together before reaching the ADC module,
so only one timer should be used to trigger ADC events.
The GPT Module is one timing resource available on the Stellaris^® microcontrollers. Other timer
resources include the System Timer (SysTick) (see “System Timer (SysTick)” on page 76).
The General-Purpose Timer Module (GPTM) contains four GPTM blocks with the following functional
options:
■ Count up or down
■ 16- or 32-bit programmable one-shot timer
■ 16- or 32-bit programmable periodic timer
■ 16-bit general-purpose timer with an 8-bit prescaler
■ 32-bit Real-Time Clock (RTC) when using an external 32.768-KHz clock as the input
■ Eight Capture Compare PWM pins (CCP)
■ Daisy chaining of timer modules to allow a single timer to initiate multiple timing events
■ ADC event trigger
■ User-enabled stalling when the controller asserts CPU Halt flag during debug (excluding RTC
mode)
■ 16-bit input-edge count- or time-capture modes
■ 16-bit PWM mode with software-programmable output inversion of the PWM signal
■ Ability to determine the elapsed time between the assertion of the timer interrupt and entry into
the interrupt service routine.
■ Efficient transfers using Micro Direct Memory Access Controller (µDMA)
– Dedicated channel for each timer
– Burst request generated on timer interrupt
June 29, 2010
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Texas Instruments-Advance Information