13
General-Purpose Timers
Programmable timers can be used to count or time external events that drive the Timer input pins.
The TM4C1294NCPDT General-Purpose Timer Module (GPTM) contains 16/32-bit GPTM blocks.
Each 16/32-bit 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 concatenated 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 Tiva™ C Series microcontrollers. Other
timer resources include the System Timer (SysTick) (see 135) and the PWM timer in the PWM module
(see “PWM Timer” on page 1672).
The General-Purpose Timer Module (GPTM) contains eight 16/32-bit GPTM blocks with the following
functional options:
■ Operating modes:
– 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
– 16-bit input-edge count- or time-capture modes with an 8-bit prescaler
– 16-bit PWM mode with an 8-bit prescaler and software-programmable output inversion of the
PWM signal
– The System Clock or a global Alternate Clock (ALTCLK) resource can be used as timer clock
source. The global ALTCLK can be:
•
PIOSC
•
Hibernation Module Real-time clock output (RTCOSC)
•
Low-frequency internal oscillator (LFIOSC)
■ Count up or down
■ Twelve 16/32-bit Capture Compare PWM pins (CCP)
■ Daisy chaining of timer modules to allow a single timer to initiate multiple timing events
■ Timer synchronization allows selected timers to start counting on the same clock cycle
■ ADC event trigger
■ User-enabled stalling when the microcontroller asserts CPU Halt flag during debug (excluding
RTC mode)
955
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller
